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1

Mechanisms of Phosphine Toxicity  

PubMed Central

Fumigation with phosphine gas is by far the most widely used treatment for the protection of stored grain against insect pests. The development of high-level resistance in insects now threatens its continued use. As there is no suitable chemical to replace phosphine, it is essential to understand the mechanisms of phosphine toxicity to increase the effectiveness of resistance management. Because phosphine is such a simple molecule (PH3), the chemistry of phosphorus is central to its toxicity. The elements above and below phosphorus in the periodic table are nitrogen (N) and arsenic (As), which also produce toxic hydrides, namely, NH3 and AsH3. The three hydrides cause related symptoms and similar changes to cellular and organismal physiology, including disruption of the sympathetic nervous system, suppressed energy metabolism and toxic changes to the redox state of the cell. We propose that these three effects are interdependent contributors to phosphine toxicity.

Nath, Nisa S.; Bhattacharya, Ishita; Tuck, Andrew G.; Schlipalius, David I.; Ebert, Paul R.

2011-01-01

2

Molecular Structure of Phosphine  

NSDL National Science Digital Library

Phosphine, also known as phosphane, hydrogen phosphide, or phosphorus hydride, is a toxic gas for insects (and humans) and has an odor of decaying fish. Phosphine is an air pollutant and a natural product of swamps and sewers. It is used as a grain fumigant and as an insecticide for fumigation of animal feed, leaf stored tobacco, box cars, and for rodent control. Phosphine is also widely employed as an industrial gas in silicon chip manufacture, in explosives, friction matches, fireworks, toothpaste, and detergents.

2003-06-04

3

Phosphorus cycling through phosphine in paddy fields  

Microsoft Academic Search

Phosphine emission fluxes from paddy fields, phosphine ambient levels in air, and the vertical profile of matrix-bound phosphine in soil have been measured throughout the growing season of rice in Beijing, China. It was found that both the seasonal and diurnal emission fluxes and ambient levels fluctuate significantly. During the drainage period, phosphine released from the soil with the highest

Sheng-Hui Han; Ya-Hui Zhuang; Ji-Ang Liu; Dietmar Glindemann

2000-01-01

4

Coordination chemistry with phosphine and phosphine oxide-substituted hydroxyferrocenes.  

PubMed

New unsymmetrical hydroxyferrocenes were synthesised from dibromoferrocene. The oxygen heteroatom was introduced via lithiation and quenching with bis-trimethylsilylperoxide followed by hydrolysis to unmask the hydroxyl functionality. The coordination chemistry of 1'-(diphenylphosphino)-1-hydroxyferrocene 2 was explored with palladium and rhodium precursors. A dinuclear palladium methyl complex with bridging ferrocenyloxo groups was obtained from the reaction between 2 and (cyclooctadiene)methylchloropalladium(II). With tetracarbonyldichlorodirhodium(I), two complexes were isolated. The major product was a bis ligand cis phosphine ligated complex with one ligand bound in a chelating mode and one with a pendant hydroxyl group. A minor product was crystallographically characterised as a dinuclear ferrocenyloxo-bridged rhodium carbonyl complex. The coordination chemistry of 2 and the corresponding phosphine oxide 3 was examined with group 4 metals and the resulting complexes examined as ethylene polymerisation catalysts. The ligands were found to bind in either a chelating fashion or with pendant phosphine donors. In all cases, low to moderately active ethylene polymerisation catalysts were found. The catalysts were very unstable and catalyst residues were observed in the isolated polymer indicating a short catalyst lifetime. PMID:20614060

Atkinson, Robert C J; Gibson, Vernon C; Long, Nicholas J; White, Andrew J P

2010-08-28

5

Phosphine catalysis of allenes with electrophiles.  

PubMed

Nucleophilic phosphine catalysis of allenes with electrophiles is one of the most powerful and straightforward synthetic strategies for the generation of highly functionalized carbocycle or heterocycle structural motifs, which are present in a wide range of bioactive natural products and medicinally important substances. The reaction topologies can be controlled through a judicious choice of the phosphine catalyst and the structural variations of starting materials. This Tutorial Review presents selected examples of nucleophilic phosphine catalysis using allenes and electrophiles. PMID:24663290

Wang, Zhiming; Xu, Xingzhu; Kwon, Ohyun

2014-05-01

6

?-Cationic Phosphines: Synthesis and Applications.  

PubMed

In coordination chemistry, typical ancillary ligands are anionic or neutral species. Cationic ones are exceptions and, when used, the positively charged groups are normally attached to the periphery and not close to the donating atom. However, this concept article highlights a series of recent experimental, as well as theoretical results, suggesting that the utility in catalysis of cationic phosphines with no spacer between the phosphorus atom and the positively charged group(s) has been largely overlooked. In fact, a growing number of studies indicate that, because of their specific architecture, these cationic ligands depict excellent ?-acceptor character that can exceed that of phosphites or polyfluorinated phosphines. This property has been used to increase the Lewis acidity of the metals they coordinate. Specifically, new extreme ?-acid catalysts, mainly based on Pt(II) and Au(I) , have been recently prepared and their superior performance demonstrated along several mechanistically distinct transformations. In this concept article the current state of the art is critically assessed and possible future directions of the topic discussed. PMID:24890133

Alcarazo, Manuel

2014-06-23

7

Phosphine photochemistry in Saturn's atmosphere  

NASA Technical Reports Server (NTRS)

The phosphine photochemistry on Saturn is studied with a 1D photochemical model. The PH3 concentration is rapidly depleted with height (scale height 3.5 km) in the upper troposphere. Formation of P, a probable precursor of P4, (a potential red chromophore in the atmosphere), is highly improbable unless the rate constant for the recombination reaction PH + H2 + M yields PH3 + M is less than 10 to the -41st cm exp 6/molecule-squared sec. Coupling of PH3 and hydrocarbon photochemistry, specifically the C2H2 catalyzed photodissociation of CH, is important. Column production rates of the organophosphorus compounds CH3PH2 and HCP of 3 x 10 to the 8th/sq cm sec are predicted, with potentially observable column densities of greater than 1 x 10 to the 17th/sq cm.

Kaye, J. A.; Strobel, D. F.

1983-01-01

8

COBALT(II) COMPLEXES WITH PHOSPHINE OXIDES  

Microsoft Academic Search

Solid complexes of tribenzylphosphine oxide (tbpo), dibenzylphenylphosphine oxide (dbppo) and benzyldiphenyl-phosphine oxide (bdppo) with Cobalt(II) chloride, bromide, iodide, thiocyanate, nitrate and perchlorate are reported and characterized. The compounds have the general formulas [CoL2 X2] and [CoL4] (C?O4)2, where L is the phosphine oxide and X = Cl, Br, I, NCS or NO3. They are characterized and identified by chemical analysis

A. C. Massabni; O. A. Serra

1977-01-01

9

Polytertiary Phosphines and Arsines. VII. Zerovalent Platinum Complexes of Arylated Polytertiary Phosphines and Arsines.  

National Technical Information Service (NTIS)

Zerovalent platinum complexes of polytertiary phosphines and phosphine-arsines can be prepared by reaction of a mixture of K2PtCl4 and the ligand with sodium borohydride in aqueous ethanol. The chelating bidentate ligands (m-CH3C6H4)2PCH2CH2P(C6H5)2, (C6H...

P. N. Kapoor R. B. King

1971-01-01

10

Cs2CO3-promoted one-pot synthesis of alkynylphosphonates, -phosphinates, and -phosphine oxides.  

PubMed

A novel and efficient Cs2CO3-promoted phosphorylation or phosphinylation of various 1,1-dibromo-1-alkenes with readily available trialkyl phosphites, ethyl diphenylphosphinite, or diethyl phenylphosphonite has been developed under metal-free conditions, providing a practical and powerful tool for one-pot synthesis of valuable alkynylphosphonates, -phosphinates, and -phosphine oxides in good to excellent yields. PMID:24661190

Wang, Yulei; Gan, Jiepeng; Liu, Liu; Yuan, Hang; Gao, Yuxing; Liu, Yan; Zhao, Yufen

2014-04-18

11

Process for Synthesis of Phosphonic Acids and Phosphinic Acids.  

National Technical Information Service (NTIS)

A process is claimed for the synthesis of phosphonic and phosphinic acids by hydrolysis of the corresponding esters. The phosphonic and phosphinic acids produced act as catalysts in the process, which is characterized by the fact that the hydrolysis proce...

H. D. Block H. Kohnen

1983-01-01

12

Synthesis and modifications of phosphinic dipeptide analogues.  

PubMed

Pseudopeptides containing the phosphinate moiety (-P(O)(OH)CH(2)-) have been studied extensively, mainly as transition state analogue inhibitors of metalloproteases. The key synthetic aspect of their chemistry is construction of phosphinic dipeptide derivatives bearing appropriate side-chain substituents. Typically, this synthesis involves a multistep preparation of two individual building blocks, which are combined in the final step. As this methodology does not allow simple variation of the side-chain structure, many efforts have been dedicated to the development of alternative approaches. Recent achievements in this field are summarized in this review. Improved methods for the formation of the phosphinic peptide backbone, including stereoselective and multicomponent reactions, are presented. Parallel modifications leading to the structurally diversified substituents are also described. Finally, selected examples of the biomedical applications of the title compounds are given. PMID:23154272

Mucha, Artur

2012-01-01

13

Organophosphorus catalysis to bypass phosphine oxide waste.  

PubMed

The conversion of oxygen-containing compounds is often achieved by the use of phosphorus reagents. The newly formed phosphine oxide bond delivers the enthalpic gain that drives reactions, such as the Wittig, Mitsunobu, and Appel reaction, to completion. However, phosphine oxides are recognized as undesirable waste products and in the past decade several methods have emerged that address this issue by in situ regeneration of the phosphorus reagent. This Minireview outlines the two distinct strategies and underpinning research that led to these advances. The potential of the emerging field of phosphorus catalysis in chemistry is shown and new developments that may stimulate further research are described. PMID:24039197

van Kalkeren, Henri A; van Delft, Floris L; Rutjes, Floris P J T

2013-09-01

14

Phosphine-directed c?h borylation reactions: facile and selective access to ambiphilic phosphine boronate esters.  

PubMed

Ambiphilic ligands have received considerable attention over the last two decades due to their unique reactivity as organocatalysts and ligands. The iridium-catalyzed C?H borylation of phosphines is described in which the phosphine is used as a directing group to provide selective formation of arylboronate esters with unique scaffolds of ambiphilic compounds. A variety of aryl and benzylic phosphines were subjected to the reaction conditions, selectively providing stable, isolable boronate esters upon protection of the phosphine as the borane complex. After purification, the phosphine-substituted boronate esters could be deprotected and isolated in pure form. PMID:24895243

Crawford, Kristina M; Ramseyer, Timothy R; Daley, Christopher J A; Clark, Timothy B

2014-07-14

15

Phosphine from rocks: mechanically driven phosphate reduction?  

PubMed

Natural rock and mineral samples released trace amounts of phosphine during dissolution in mineral acid. An order of magnitude more phosphine (average 1982 ng PH3 kg rock and maximum 6673 ng PH3/kg rock) is released from pulverized rock samples (basalt, gneiss, granite, clay, quartzitic pebbles, or marble). Phosphine was correlated to hardness and mechanical pulverization energy of the rocks. The yield of PH3 ranged from 0 to 0.01% of the total P content of the dissolved rock. Strong circumstantial evidence was gathered for reduction of phosphate in the rock via mechanochemical or "tribochemical" weathering at quartz and calcite/marble inclusions. Artificial reproduction of this mechanism by rubbing quartz rods coated with apatite-phosphate to the point of visible triboluminescence, led to detection of more than 70 000 ng/kg PH3 in the apatite. This reaction pathway may be considered a mechano-chemical analogue of phosphate reduction from lightning or electrical discharges and may contribute to phosphine production via tectonic forces and processing of rocks. PMID:16294866

Glindemann, Dietmar; Edwards, Marc; Morgenstern, Peter

2005-11-01

16

PHOSCARD® PHOSPHINE FUMIGATION DETECTOR CARDS FOR FARMERS  

Microsoft Academic Search

Western Australia exports around 80% of its annual grain harvest to markets that are becoming more discerning with respect to insect infestation and chemical residues. The state is well placed to meet these markets through its extensive use of phosphine (PH3) fumigation both on-farm and in the central handling system. This marketing advantage is threatened by PH3 resistance and safety

R. N. EMERY; E. KOSTAS

17

P-arylation: arynes to aryl-phosphonates, -phosphinates, and -phosphine oxides.  

PubMed

Synthesis of organo-phosphorus compounds and their application in organic synthesis and life sciences has been a topic of contemporary interest. Michaelis-Arbuzov reaction is the most extensively utilized method for their preparation, which works well only with aliphatic halides. Hence, relatively harsh reaction conditions using transition-metal-catalyzed P-arylation (Arbuzov/Hirao reaction) are used for the preparation of aryl-phosphorus compounds. Presented herein is a competent process for the synthesis of aryl-phosphonates, -phosphinates, and -phosphine oxides by making an efficient use of arynes for C-P bond construction. PMID:23590457

Dhokale, Ranjeet A; Mhaske, Santosh B

2013-05-01

18

Preparation of phosphines through C-P bond formation  

PubMed Central

Summary Phosphines are an important class of ligands in the field of metal-catalysis. This has spurred the development of new routes toward functionalized phosphines. Some of the most important C–P bond formation strategies were reviewed and organized according to the hybridization of carbon in the newly formed C–P bond.

Wauters, Iris; Debrouwer, Wouter

2014-01-01

19

Preparation of phosphines through C-P bond formation.  

PubMed

Phosphines are an important class of ligands in the field of metal-catalysis. This has spurred the development of new routes toward functionalized phosphines. Some of the most important C-P bond formation strategies were reviewed and organized according to the hybridization of carbon in the newly formed C-P bond. PMID:24991257

Wauters, Iris; Debrouwer, Wouter; Stevens, Christian V

2014-01-01

20

Synthesis of a phosphine imide bearing a hydrosilane moiety, and its water-driven reduction to a phosphine.  

PubMed

Organosilanes bearing a phosphine imide moiety were synthesized and crystallographically characterized. Reaction of the pentacoordinated hydrodiphenylsilyl derivative with water gave [2-(diphenylphosphino)phenyl]diphenylsilanol accompanied by both reduction of the phosphine imide moiety and hydrolytic oxidation of the Si-H moiety. PMID:23807626

Kano, Naokazu; Yanaizumi, Kazuhide; Meng, Xiangtai; Havare, Nizam; Kawashima, Takayuki

2013-11-14

21

Prototypical Phosphine Complexes of Antimony(III).  

PubMed

Complexes of the generic formula [Cln(PR3)mSb]((3-n)+) (n = 1, 2, 3, or 4 and m = 1 or 2) have been prepared featuring [ClSb](2+), [Cl2Sb](1+), Cl3Sb, or [Cl4Sb](1-) as acceptors with one or two phosphine ligands {PMe3, PPh3, PCy3 (Cy = C6H11)}. The solid-state structures of the complexes reveal foundational features that define the coordination chemistry of a lone pair bearing stibine acceptor site. The experimental observations are interpreted with dispersion-corrected density functional theory calculations to develop an understanding of the bonding and structural diversity. PMID:24773563

Chitnis, Saurabh S; Burford, Neil; McDonald, Robert; Ferguson, Michael J

2014-05-19

22

Sublethal exposure to phosphine decreases offspring production in strongly phosphine resistant female red flour beetles, Tribolium castaneum (Herbst).  

PubMed

The red flour beetle is a cosmopolitan pest of stored grain and stored grain products. The pest has developed resistance to phosphine, the primary chemical used for its control. The reproductive output of survivors from a phosphine treatment is an important element of resistance development but experimental data are lacking. We exposed mated resistant female beetles to 0.135 mg/L of phosphine for 48 h at 25 °C. Following one week of recovery we provided two non-exposed males to half of the phosphine exposed females and to half of the non-exposed control females. Females that had been exposed produced significantly fewer offspring than non-exposed females. Females that remained isolated produced significantly fewer offspring than both exposed females with access to males and non-exposed controls (P<0.05). Some females were permanently damaged from exposure to phosphine and did not reproduce even when given access to males. We also examined the additional effects of starvation prior to phosphine exposure on offspring production. Non-exposed starved females experienced a small reduction in mean offspring production in the week following starvation, followed by a recovery in the second week. Females that were starved and exposed to phosphine demonstrated a very significant reduction in offspring production in the first week following exposure which remained significantly lower than that of starved non-exposed females (P<0.05). These results demonstrate a clear sublethal effect of phosphine acting on the female reproductive system and in some individuals this can lead to permanent reproductive damage. Pest population rebound after a fumigation may be slower than expected which may reduce the rate of phosphine resistance development. The results presented strongly suggest that phosphine resistance models should include sublethal effects. PMID:23300916

Ridley, Andrew W; Magabe, Seymour; Schlipalius, David I; Rafter, Michelle A; Collins, Patrick J

2012-01-01

23

Reaction of chloromethyliso(thio)cyanato(thio)phosphonates(-phosphinates) with phenol, ethanol, and thiols  

Microsoft Academic Search

(Chloromethyl)isocyanatophosphonates(-phosphinates) take up phenol to form carbamates whose ß-cleavage gives rise to phenyl (chloromethyl)phosphonates(-phosphinates). (Chloromethyl)(thio)phosphinic-(phosphonic) isothiocyanates react with phenol at 20°C in the absence of catalyst to afford phenyl phosphinates(-phosphonates). (Alkylsulfanyl)carbamates formed by addition of thiols to (chloromethyl)iso(thio)cyanastophosphonates(-phosphinates) under the action of an equimolar amount of triethylamine undergo cyclization into 1,3,4-oxaza(thiaza)phospholines.

N. A. Khailova; R. Kh. Bagautdinova; A. A. Shaimardanova; N. E. Krepysheva; M. A. Pudovik; G. A. Chmutova; N. M. Azancheev; R. Z. Musin; A. N. Pudovik

2004-01-01

24

Comparison of Aromatic Dithio-phosphinic and Phosphinic Acid Derivatives for Minor Actinide Extraction  

SciTech Connect

A new extractant for the separation of actinide(III) and lanthanide(III), bis(o-trifluoromethylphenyl) phosphinic acid (O-PA) was synthesized. The synthetic route employed mirrors one that was employed to produce the sulfur containing analog bis(o-trifluoromethylphenyl) dithio-phosphinic acid (S-PA). Multinuclear NMR spectroscopy was used for elementary characterization of the new O-PA derivative. This new O-PA extractant was used to perform Am(III)/Eu(III) separations and the results were directly compared to those obtained in identical separation experiments using S-PA, an extractant that is known to exhibit separation factors of {approx}100,000 at low pH. The separations data are presented and discussed in terms comparing the nature of the oxygen atom as a donor to that of the sulfur atom in extractants that are otherwise identical. (authors)

Harrup, Mason K.; Peterman, Dean R.; Greenhalgh, Mitchell R.; Luther, Thomas A.; Klaehn, John [Idaho National Laboratory, Idaho Falls, ID, 83415 (United States)

2008-07-01

25

A General Method for Determining the Optical Purity of Phosphines.  

National Technical Information Service (NTIS)

Contemporary techniques for obtaining optically active phosphines and their derivatives are not complemented by any single widely applicable method for the determination of optical purities in this class of compounds. Enantiomeric ratios, and consequently...

J. P. Casey R. A. Lewis K. Mislow

1969-01-01

26

Hydroxyalkyl phosphine compounds for use as diagnostic and therapeutic pharmaceuticals  

DOEpatents

This research discloses a compound and method of making a compound for use as a diagnostic or therapeutic pharmaceutical comprises a functionalized hydroxyalkyl phosphine ligand and a metal combined with the ligand. 16 figs.

Katti, K.V.; Singh, P.R.; Reddy, V.S.; Katti, K.K.; Volkert, W.A.; Ketring, A.R.

1999-03-02

27

HIGH DOSE PHOSPHINE FUMIGATION USING ON-SITE MIXING  

Microsoft Academic Search

Methyl bromide (MB) is relied on to maintain insect free grain exports from Queensland Australia. The eminent demise of this fumigant has been the catalyst for the trials conducted at the Globex International Gladstone Port Terminal using high doses of phosphine (PH3) at 1 mg\\/L, 2 mg\\/L and 3 mg\\/L. The trials compared on-site mixing of ECO2FUME and Phosphine\\/air mix

B. BRIDGEMAN; R. RYAN; D. GOCK; P. COLLINS

28

The Specific Heat of Disordered Antiferromagnetic Chains: Poly(Metal Phosphinates).  

National Technical Information Service (NTIS)

The inorganic transition-metal polymers, poly(metal phosphinates), comprise a unique and versatile class of new materials. In particular, three poly(chromium phosphinates) have been shown to form linear polymeric molecules which may be described in terms ...

T. S. Wei J. C. Scott A. F. Garito A. J. Heeger P. Nannelli

1975-01-01

29

Responses of Phosphate Transporter Gene and Alkaline Phosphatase in Thalassiosira pseudonana to Phosphine  

PubMed Central

Phosphine, which is released continuously from sediment, can affect the eco-physiological strategies and molecular responses of phytoplankton. To examine the effects of phosphine on phosphorus uptake and utilization in Thalassiosira pseudonana, we examined the transcriptional level of the phosphate transporter gene (TpPHO) and the activity of alkaline phosphatase (AKP) in relation to supplement of various concentrations of phosphine. TpPHO expression was markedly promoted by phosphine in both the phosphate-deficient and phosphate-4 µM culture. However, high phosphine concentrations can inhibit TpPHO transcription in the declining growth phase. AKP activity was also higher in the phosphine treatment groups than that of the control. It increased with increasing phosphine concentration in the range of 0 to 0.056 µM but was inhibited by higher levels of phosphine. These responses revealed that phosphine can affect phosphate uptake and utilization in T. pseudonana. This result was consistent with the effect of phosphine on algal growth, while TpPHO expression and AKP were even more sensitive to phosphine than algal growth. This work provides a basic understanding for further research about how phosphine affects phytoplankton.

Fu, Mei; Song, Xiuxian; Yu, Zhiming; Liu, Yun

2013-01-01

30

40 CFR 721.10135 - Phosphinic acid, P,P-diethyl-, zinc salt (2:1).  

Code of Federal Regulations, 2011 CFR

...Phosphinic acid, P,P-diethyl-, zinc salt (2:1). 721.10135 Section 721...Phosphinic acid, P,P-diethyl-, zinc salt (2:1). (a) Chemical substance...phosphinic acid, P,P-diethyl-, zinc salt (2:1) (PMN P-05-11; CAS...

2011-07-01

31

40 CFR 721.10135 - Phosphinic acid, P,P-diethyl-, zinc salt (2:1).  

Code of Federal Regulations, 2012 CFR

...Phosphinic acid, P,P-diethyl-, zinc salt (2:1). 721.10135 Section 721...Phosphinic acid, P,P-diethyl-, zinc salt (2:1). (a) Chemical substance...phosphinic acid, P,P-diethyl-, zinc salt (2:1) (PMN P-05-11; CAS...

2012-07-01

32

40 CFR 721.10135 - Phosphinic acid, P,P-diethyl-, zinc salt (2:1).  

Code of Federal Regulations, 2010 CFR

...Phosphinic acid, P,P-diethyl-, zinc salt (2:1). 721.10135 Section 721...Phosphinic acid, P,P-diethyl-, zinc salt (2:1). (a) Chemical substance...phosphinic acid, P,P-diethyl-, zinc salt (2:1) (PMN P-05-11; CAS...

2010-07-01

33

Unintentional poisoning by phosphine released from aluminum phosphide.  

PubMed

Aluminum phosphide as a releaser of phosphine gas is used as a grain preservative. In this case report, we describe an accidental severe poisoning in a 35-year-old woman, her 18-year-old daughter, and 6-year-old son caused by inhalation of phosphine gas released from 20 tablets of aluminum phosphide stored in 15 rice bags. The boy died 2 days after exposure before admission to hospital and any special treatment, but the others were admitted 48 h after exposure. They had signs and symptoms of severe toxicity, and their clinical course included metabolic acidosis, electrocardiographic changes, and hypotension. They were treated by intravenous administration of sodium bicarbonate, magnesium sulfate, and calcium gluconate. The patients were discharged after 3 days and followed up for 1 week after discharge. Rapid absorption of phosphine by inhalation, induction of hyperglycemia, and surviving of patients are interesting issues of this case report. PMID:18480154

Shadnia, S; Mehrpour, O; Abdollahi, M

2008-01-01

34

New electron-rich chiral phosphines for asymmetric catalysis  

SciTech Connect

The authors describe a new series of chiral mono- and bidentate 2,5-disubstituted phospholanes and demonstrate their use as ligands in asymmetric catalysis. Rhodium complexes bearing the new phosphine ligands were prepared and characterized by X-ray crystallography. These complexes act as efficient catalyst precursors for the enantioselective hydrogenation of unsaturated substrates.

Burk, M.J.; Feaster, J.E.; Harlow, R.L. (E.I. du Pont de Nemours and Co., Wilmington, DE (United States))

1990-10-01

35

Submicromolar Phosphinic Inhibitors of E. coli Aspartate Transcarbamoylase  

PubMed Central

The design, syntheses, and enzymatic activity of two submicromolar competitive inhibitors of aspartate transcarbamoylase (ATCase) are described. The phosphinate inhibitors are analogs of N-phosphonacetyl-L-aspartate (PALA) but have a reduced charge at the phosphorus moiety. The mechanistic implications are discussed in terms of a possible cyclic transition-state during enzymatic catalysis.

Coudray, Laetitia; Kantrowitz, Evan R.; Montchamp, Jean-Luc

2009-01-01

36

Characterizing Exoplanet Atmospheres : A Complete Line List for Phosphine  

NASA Astrophysics Data System (ADS)

The ability to characterise the atmospheres of cool stars, brown dwarfs and exoplanets requires fundamental data for all species contributing significantly to their opacity. However, with notable exceptions such as water and ammonia, existing molecular line lists are not sufficiently accurate or complete to allow for a full spectroscopic analysis of these bodies. ExoMol (www.exomol.com [1]) is a project that aims to rectify this by generating comprehensive line lists for all molecules likely to be detected in the atmospheres of cool astrophysical objects in the foreseeable future. The spectral data is generated by employing ab initio quantum mechanical methods, performing empirical refinement based on experimental spectroscopic data and harnessing high performance computing. Here we present our work on phosphine, (PH3), an equilateral pyramidal molecule (the phosphorus analogue to ammonia). Phosphine is known to be important for the atmospheres of giant-planets, cool stars and many other astronomical bodies. Rotational transition features of phosphine have been found in the far- infrared spectra of Saturn and Jupiter [2, 3], where it is a marker for vertical convection zones. A computed room temperature line list of phosphine is presented here [4], illustrated in the accompanying figure 1. This line list is a precursor to a high temperature equivalent to be produced in the near future, necessary for the analysis of cool stars and brown dwarfs. All the transitions' energy levels and Einstein A-coefficients were computed using the program TROVE [5].

Sousa-Silva, C.; Yurchenko, S. N.; Tennyson, J.

2013-09-01

37

Poly(Tertiary Phosphines and Arsines). XI. Phosphorus-31 Nuclear Magnetic Resonance Studies on Some Metal Complexes of Poly(Tertiary, Phosphines).  

National Technical Information Service (NTIS)

Proton noise-decoupled pulsed Fourier transform phosphorus-31 NMR spectra of metal complexes of the di(tertiary phosphine) (CH3)2PCH2CH2P(C6H5)2, the symmetrical tri(tertiary Phosphines) R'P(CH2CH2PR2) (R and R' = methyl or phenyl), the unsymmetrical tri(...

R. B. King J. C. Cloyd

1974-01-01

38

Advances in nucleophilic phosphine catalysis of alkenes, allenes, alkynes, and MBHADs.  

PubMed

In nucleophilic phosphine catalysis, tertiary phosphines undergo conjugate additions to activated carbon-carbon multiple bonds to form ?-phosphonium enolates, ?-phosphonium dienolates, ?-phosphonium enoates, and vinyl phosphonium ylides as intermediates. When these reactive zwitterionic species react with nucleophiles and electrophiles, they may generate carbo- and heterocycles with multifarious molecular architectures. This article describes the reactivities of these phosphonium zwitterions, the applications of phosphine catalysis in the syntheses of biologically active compounds and natural products, and recent developments in the enantioselective phosphine catalysis. PMID:24196409

Fan, Yi Chiao; Kwon, Ohyun

2013-12-25

39

Oxygen plasma resistant phosphine oxide containing imide/arylene copolymers  

NASA Technical Reports Server (NTRS)

A series of oxygen plasma resistant imide/arylene ether copolymers were prepared by reacting anhydride-terminated poly(amide acids) and amine-terminated polyarylene ethers containing phosphine oxide units. Inherent viscosities for these copolymers ranged from 0.42 to 0.80 dL/g. After curing, the resulting copolymers had glass transition temperatures ranging from 224 C to 228 C. Solution cast films of the block copolymers were tough and flexible with tensile strength, tensile moduli, and elongation at break up to 16.1 ksi, 439 ksi, and 23 percent, respectively at 25 C and 9.1 ksi, 308 ksi and 97 percent, respectively at 150 C. The copolymers show a significant improvement in resistance to oxygen plasma when compared to the commercial polyimide Kapton. The imide/arylene ether copolymers containing phosphine oxide units are suitable as coatings, films, adhesives, and composite matrices.

Jensen, Brian J.

1993-01-01

40

Synthesis of binaphthyl based phosphine and phosphite ligands.  

PubMed

The development of large scale synthesis of enantiopure and thermally stable (R)- and (S)-BINOL molecules constitutes a key milestone in the field of asymmetric catalysis. Particularly, a great variety of chiral binaphthyl-based phosphorus compounds, herein represented by phosphite and phosphine classes, have earned considerable relevance due to their versatility as ligands in enantioselective metal-catalysed reactions, allowing the preparation of optically active products with the desired enantiopurity. This review highlights the most relevant concepts and accounts regarding general synthetic procedures for binaphthyl-based mono- and bidentate phosphites and phosphines. Furthermore, the search for environmentally benign chemical catalytic processes compelled us to also give special attention to the functionalisation of binaphthyl-based phosphorus ligands for use in alternative reaction media. When available, a critical selection of their applications in catalysis is briefly assessed. PMID:23783506

Pereira, Mariette M; Calvete, Mário J F; Carrilho, Rui M B; Abreu, Artur R

2013-08-21

41

Biaryl Phosphine Ligands in Palladium-Catalyzed Amination  

PubMed Central

Palladium-catalyzed amination of aryl halides has undergone rapid development in the last 12 years. This has been largely driven by implementation of new classes of ligands. Biaryl phosphines have proven to provide especially active catalysts in this context. This review discusses the applications that these catalysts have found in C-N cross-coupling in heterocycle synthesis, pharmaceuticals, materials science and natural product synthesis.

Surry, David S.

2012-01-01

42

Retrievals of Jovian Tropospheric Phosphine from Cassini/CIRS  

NASA Technical Reports Server (NTRS)

On December 30th 2000, the Cassini-Huygens spacecraft reached the perijove milestone on its continuing journey to the Saturnian system. During an extended six-month encounter, the Composite Infrared Spectrometer (CIRS) returned spectra of the Jovian atmosphere, rings and satellites from 10-1400 cm(exp -1) (1000-7 microns) at a programmable spectral resolution of 0.5 to 15 cm(exp -1). The improved spectral resolution of CIRS over previous IR instrument-missions to Jupiter, the extended spectral range, and higher signal-to-noise performance provide significant advantages over previous data sets. CIRS global observations of the mid-infrared spectrum of Jupiter at medium resolution (2.5 cm(exp -1)) have been analysed both with a radiance differencing scheme and an optimal estimation retrieval model to retrieve the spatial variation of phosphine and ammonia fractional scale height in the troposphere between 60 deg S and 60 deg N at a spatial resolution of 6 deg. The ammonia fractional scale height appears to be high over the Equatorial Zone (EZ) but low over the North Equatorial Belt (NEB) and South Equatorial Belt (SEB) indicating rapid uplift or strong vertical mixing in the EZ. The abundance of phosphine shows a similar strong latitudinal variation which generally matches that of the ammonia fractional scale height. However while the ammonia fractional scale height distribution is to a first order symmetric in latitude, the phosphine distribution shows a North/South asymmetry at mid latitudes with higher amounts detected at 40 deg N than 40 deg S. In addition the data show that while the ammonia fractional scale height at this spatial resolution appears to be low over the Great Red Spot (GRS), indicating reduced vertical mixing above the approx. 500 mb level, the abundance of phosphine at deeper levels may be enhanced at the northern edge of the GRS indicating upwelling.

Irwin, P. G. J.; Parrish, P.; Fouchet, T.; Calcutt, S. B.; Taylor, F. W.; Simon-Miller, A. A.; Nixon, C. A.

2004-01-01

43

Poly(Tertiary Phosphines and Arsines)- XII. Some Metal Complexes of Methylated DI- and Tri (Tertiary Phosphines).  

National Technical Information Service (NTIS)

Metal complexes of the di(tertiary phosphine) (CH3)2PCH2Ch2P(C6H5)2 of the types (diphos) MCl2 (M=Ni, Co, Pd, and Pt), (diphos)M(CO)4 (M=Cr, Mo, and W), ((diphos)2-RhCl2)(+), and (diphosFe2(CO)2(C5H5)2 have been prepared by standard methods. Metal complex...

R. B. King J. A. Zinich J. C. Cloyd

1974-01-01

44

Ruthenium bidentate phosphine complexes for the coordination and catalytic dehydrogenation of amine- and phosphine-boranes.  

PubMed

Addition of the amine-boranes H(3)B?NH(2)tBu, H(3)B?NHMe(2) and H(3)B?NH(3) to the cationic ruthenium fragment [Ru(xantphos)(PPh(3))(OH(2))H][BAr(F)(4)] (2; xantphos=4,5-bis(diphenylphosphino)-9,9-dimethylxanthene; BAr(F)(4)=[B{3,5-(CF(3))(2)C(6)H(3)}(4)](-)) affords the ?(1)-B-H bound amine-borane complexes [Ru(xantphos)(PPh(3))(H(3)B?NH(2)tBu)H][BAr(F)(4)] (5), [Ru(xantphos)(PPh(3))(H(3) B?NHMe(2))H][BAr(F)(4)] (6) and [Ru(xantphos)(PPh(3))(H(3)B?NH(3))H][BAr(F)(4)] (7). The X-ray crystal structures of 5 and 7 have been determined with [BAr(F)(4)] and [BPh(4)] anions, respectively. Treatment of 2 with H(3)B?PHPh(2) resulted in quite different behaviour, with cleavage of the B-P interaction taking place to generate the structurally characterised bis-secondary phosphine complex [Ru(xantphos)(PHPh(2))(2)H][BPh(4)] (9). The xantphos complexes 2, 5 and 9 proved to be poor precursors for the catalytic dehydrogenation of H(3)B?NHMe(2). While the dppf species (dppf=1,1'-bis(diphenylphosphino)ferrocene) [Ru(dppf)(PPh(3))HCl] (3) and [Ru(dppf)(?(6)-C(6)H(5)PPh(2))H][BAr(F)(4)] (4) showed better, but still moderate activity, the agostic-stabilised N-heterocyclic carbene derivative [Ru(dppf)(ICy)HCl] (12; ICy=1,3-dicyclohexylimidazol-2-ylidene) proved to be the most efficient catalyst with a turnover number of 76 h(-1) at room temperature. PMID:21678503

Ledger, Araminta E W; Ellul, Charles E; Mahon, Mary F; Williams, Jonathan M J; Whittlesey, Michael K

2011-07-25

45

31P NMR Studies of the Linear Chain Magnets: Poly(Metal Phosphinates).  

National Technical Information Service (NTIS)

The family of polymers known as poly(metal phosphinates) consists of metal ions linked in a chain-like fashion by phosphinate bridges. The metal ion in the magnetic polymers is either a 3d-transition metal or a member of the rare earth group.

L. S. Smith P. R. Newman A. J. Heeger A. F. Garito H. D. Gillman

1977-01-01

46

Hydrosilylation reactions catalyzed by rhodium complexes with phosphine ligands functionalized with imidazolium salts  

Microsoft Academic Search

Hydrosilylation reactions of styrene with triethoxysilane catalyzed by rhodium complexes with phosphine ligands functionalized with imidazolium salts are reported. In comparison with Wilkinson’s catalyst, Rh(PPh3)3Cl, all of the present rhodium complexes with phosphines functionalized with imidazolium salts exhibit higher catalytic activity and selectivity.

Jiayun Li; Jiajian Peng; Diliang Wang; Ying Bai; Jianxiong Jiang; Guoqiao Lai

2011-01-01

47

Phosphine-Mediated Heinz Body Formation and Hemoglobin Oxidation in Human Erythrocytes.  

National Technical Information Service (NTIS)

Exposure of human erythrocytes in vitro to phosphine (PH3) induces the development of Heinz body lesions. The lower limit for phosphine mediated Heinz body formation is 1.25 ppm for a four-hour exposure. At exposure levels of 3.0 ppm or higher all erythro...

W. T. Potter S. Rong J. Griffith J. White V. F. Garry

1991-01-01

48

Unprecedented selective aminolysis: Aminopropyl phosphine as a building block for a new family of air stable mono-, bis-, and tris-primary phosphines  

SciTech Connect

A serious impediment to using primary and secondary phosphines as general-purpose reagents to develop new chemistry is associated with their unpleasant pyrophoric nature and extreme hydrolytic, thermal, and oxidative instabilities. In particular, primary phosphines with ``user friendly'' properties (e.g., good oxidative/thermal stability, low volatility) would be extremely important not only from the synthetic point of view but also for potential application (e.g., in dendrimers formation). As part of ongoing research on the fundamental main group and organic chemistry of functionalized phosphorus compounds, the authors report, herein, unprecedented selectivity in the reaction of 3-aminopropyl primary phosphine 3, with the methyl ester in the presence of free acid, amide, and thiol to produce air stable amide, carboxylate, and thiol functionalized primary phosphines.

Prabhu, K.R.; Pillarsetty, N.; Gali, H.; Katti, K.V.

2000-02-23

49

Are boryl radicals from amine-boranes and phosphine-boranes the most stable radicals?  

PubMed

The relative stability of the radicals that can be produced from amine-boranes and phosphine-boranes is investigated at the G3-RAD level of theory. Aminyl ([RNH](.) :BH3 ) and phosphinyl ([RPH](.) :BH3 ) radicals are systematically more stable than the boryl analogues, [RNH2 ]:BH2 (.) and [RPH2 ]:BH2 (.) . Despite similar stability trends for [RNH](.) :BH3 and [RPH](.) :BH3 radicals with respect to boryl radicals, there are significant dissimilarities between amine- and phosphine-boranes. The homolytic bond dissociation energy of the N?H bond decreases upon association of the amines with BH3 , whereas that of the P?H bond for phosphines increases. The stabilization of the free amine is much smaller than that of the corresponding aminyl radical, whereas for phosphines this is the other way around. The homolytic bond dissociation energy of the B?H bond of borane decreases upon complexation with both amines and phosphines. PMID:24888891

Martín-Sómer, Ana; Mó, Otilia; Yáñez, Manuel

2014-08-01

50

Balancing phosphine in manure fermentation JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH PART B-PESTICIDES FOOD CONTAMINANTS AND AGRICULTURAL WASTES 32 (6): 955-968 1997  

Microsoft Academic Search

The evolution of phosphine gas during the anaerobic batch fermentation of fresh swine manure was detected and correlated to the production of methane and hydrogen sulphide. A close temporal relationship between phosphine liberation and methane formation was found. However, the gaseous phosphine released from manure during fermentation only represents a tiny fraction of the overall phosphine balance. The majority of

F. Eismann; D. Glindemann; A. Bergmann; P. Kuschk

51

Essential role of phosphines in organocatalytic ?-boration reaction.  

PubMed

The use of phosphines to assist the organocatalytic ?-boration reaction of ?,?-unsaturated carbonyl compounds has been demonstrated with a selected number of substrates. The new method eludes the use of Brönsted bases to promote the catalytic active species and PR(3) becomes essential to interact with the substrate resulting in the formation of a zwitterionic phosphonium enolate. This species can further deprotonate MeOH when B(2)pin(2) is present forming eventually the ion pair [?-(H),?-(PR(3))-ketone](+)[B(2)pin(2)·MeO](-) that is responsible for the catalysis. PMID:23147697

Pubill-Ulldemolins, Cristina; Bonet, Amadeu; Gulyás, Henrik; Bo, Carles; Fernández, Elena

2012-12-28

52

Acute and Subacute Inhalation Toxicities of Phosphine, Phenylphosphine and Triphenylphosphine  

Microsoft Academic Search

The four-hour LC50 values for ChR-CD male rats for phosphine, phenylphosphine and triphenylphosphine have been determined to be 0.44 micromoles per liter (µM\\/liter), 1.56?µM\\/liter and 47.8?µM\\/liter respectively. The dose-death curves are parallel. During exposure, all three caused clinical signs indicative of mild respiratory irritation. Triphenylphosphine also caused severe weight loss immediately after exposure, followed by normal rate of weight gain.

RICHARD S. WARITZ; RHODA M. BROWN

1975-01-01

53

Polyimides Containing Pendent Phosphine Oxide Groups for Space Applications  

NASA Technical Reports Server (NTRS)

As part of an ongoing materials development activity to produce high performance polymers that are durable to the space environment, phosphine oxide containing polyimides have been under investigation. A novel dianhydride was prepared from 2,5-dihydroxyphenyldiphenylphosphine oxide in good yield. The dianhydride was reacted with commercially available diamines, and a previously reported diamine was reacted with commercially available dianhydrides to prepare isomeric polyimides. The physical and mechanical properties, particularly thermal and optical properties, of the polymers were determined. One material exhibited a high glass transition temperature, high tensile properties, and low solar absorptivity. The chemistry, physical, and mechanical properties of these resins will be discussed.

Thompson, C. M.; Smith, J. G., Jr.; Watson, K. A.; Connell, J. W.

2002-01-01

54

Effect of the Phosphine Steric and Electronic Profile on the Rh-Promoted Dehydrocoupling of Phosphine-Boranes  

PubMed Central

The electronic and steric effects in the stoichiometric dehydrocoupling of secondary and primary phosphine–boranes H3B·PR2H [R = 3,5-(CF3)2C6H3; p-(CF3)C6H4; p-(OMe)C6H4; adamantyl, Ad] and H3B·PCyH2 to form the metal-bound linear diboraphosphines H3B·PR2BH2·PR2H and H3B·PRHBH2·PRH2, respectively, are reported. Reaction of [Rh(L)(?6-FC6H5)][BArF4] [L = Ph2P(CH2)3PPh2, ArF = 3,5-(CF3)2C6H3] with 2 equiv of H3B·PR2H affords [Rh(L)(H)(?,?-PR2BH3)(?1-H3B·PR2H)][BArF4]. These complexes undergo dehydrocoupling to give the diboraphosphine complexes [Rh(L)(H)(?,?2-PR2·BH2PR2·BH3)][BArF4]. With electron-withdrawing groups on the phosphine–borane there is the parallel formation of the products of B–P cleavage, [Rh(L)(PR2H)2][BArF4], while with electron-donating groups no parallel product is formed. For the bulky, electron rich, H3B·P(Ad)2H no dehydrocoupling is observed, but an intermediate Rh(I) ? phosphine–borane complex is formed, [Rh(L){?2-H3B·P(Ad)2H}][BArF4], that undergoes B–P bond cleavage to give [Rh(L){?1-H3B·P(Ad)2H}{P(Ad)2H}][BArF4]. The relative rates of dehydrocoupling of H3B·PR2H (R = aryl) show that increasingly electron-withdrawing substituents result in faster dehydrocoupling, but also suffer from the formation of the parallel product resulting from P–B bond cleavage. H3B·PCyH2 undergoes a similar dehydrocoupling process, and gives a mixture of stereoisomers of the resulting metal-bound diboraphosphine that arise from activation of the prochiral P–H bonds, with one stereoisomer favored. This diastereomeric mixture may also be biased by use of a chiral phosphine ligand. The selectivity and efficiencies of resulting catalytic dehydrocoupling processes are also briefly discussed.

2014-01-01

55

Do phosphine resistance genes influence movement and dispersal under starvation?  

PubMed

Phosphine resistance alleles might be expected to negatively affect energy demanding activities such as walking and flying, because of the inverse relationship between phosphine resistance and respiration. We used an activity monitoring system to quantify walking of Rhyzopertha dominica (F.) and a flight chamber to estimate their propensity for flight initiation. No significant difference in the duration of walking was observed between the strongly resistant, weakly resistant, and susceptible strains of R. dominica we tested, and females walked significantly more than males regardless of genotype. The walking activity monitor revealed no pattern of movement across the day and no particular time of peak activity despite reports of peak activity of R. dominica and Tribolium castaneum (Herbst) under field conditions during dawn and dusk. Flight initiation was significantly higher for all strains at 28 degrees C and 55% relative humidity than at 25, 30, 32, and 35 degrees C in the first 24 h of placing beetles in the flight chamber. Food deprivation and genotype had no significant effect on flight initiation. Our results suggest that known resistance alleles in R. dominica do not affect insect mobility and should therefore not inhibit the dispersal of resistant insects in the field. PMID:24224272

Kaur, Ramandeep; Ebert, Paul R; Walter, Gimme H; Swain, Anthony J; Schlipalius, David I

2013-10-01

56

Phosphine and diphosphine complexes of silicon(IV) halides.  

PubMed

The reaction of SiX4 (X = Cl or Br) with PMe3 in anhydrous CH2Cl2 forms trans-[SiX4(PMe3)2], while the diphosphines, Me2P(CH2)2PMe2, Et2P(CH2)2PEt2, and o-C6H4(PMe2)2 form cis-[SiX4(diphosphine)], all containing six-coordinate silicon centers. With Me2PCH2PMe2 the product was trans-[SiCl4(?(1)-Me2PCH2PMe2)2]. The complexes have been characterized by X-ray crystallography, microanalysis, IR, and multinuclear ((1)H, (13)C{(1)H}, and (31)P{(1)H}) NMR spectroscopies. The complexes are stable solids and not significantly dissociated in nondonor solvents, although they are very moisture and oxygen sensitive. This stability conflicts with the predictions of recent density functional theory (DFT) calculations (Wilson et al. Inorg. Chem. 2012, 51, 7657-7668) which suggested six-coordinate silicon phosphines would be unstable, and also contrasts with the failure to isolate complexes with SiF4 (George et al. Dalton Trans. 2011, 40, 1584-1593). No reaction occurred between phosphines and SiI4, or with SiX4 and arsine ligands including AsMe3 and o-C6H4(AsMe2)2. Attempts to make five-coordinate [SiX4(PR3)] using the sterically bulky phosphines, P(t)Bu3, P(i)Pr3, or PCy3 failed, with no apparent reaction occurring, consistent with predictions (Wilson et al. Inorg. Chem. 2012, 51, 7657-7668) that such compounds would be very endothermic, while the large cone angles of the phosphines presumably preclude formation of six-coordination at the small silicon center. The reaction of Si2Cl6 with PMe3 or the diphosphines in CH2Cl2 results in instant disproportionation to the SiCl4 adducts and polychlorosilanes, but from hexane solution very unstable white [Si2Cl6(PMe3)2] and [Si2Cl6(diphosphine)] (diphosphine = Me2P(CH2)2PMe2 or o-C6H4(PMe2)2) precipitate. The reactions of SiHCl3 with PMe3 and Me2P(CH2)2PMe2 also produce the SiCl4 adducts, but using Et2P(CH2)2PEt2, colorless [SiHCl3{Et2P(CH2)2PEt2}] was isolated, which was characterized by an X-ray structure which showed a pseudo-octahedral complex with the Si-H trans to P. Attempts to reduce the silicon(IV) phosphine complexes to silicon(II) were unsuccessful, contrasting with the isolation of stable N-heterocyclic carbene adducts of Si(II). PMID:23590521

Levason, William; Pugh, David; Reid, Gillian

2013-05-01

57

Phosphine-Quenching of Cyanine Dyes as a Versatile Tool for Fluorescence Microscopy  

PubMed Central

We report that the cyanine dye Cy5 and several of its structural relatives are reversibly quenched by the phosphine TCEP (tris(2-carboxyethyl)phosphine). Using Cy5 as a model, we show that the quenching reaction occurs by 1,4-addition of the phosphine to the polymethine bridge of Cy5 to form a covalent adduct. Illumination with ultraviolet light dissociates the adduct and returns the dye to the fluorescent state. We demonstrate that TCEP quenching can be used for superresolution imaging as well as for other applications, such as differentiating between molecules inside and outside the cell.

Vaughan, Joshua C.; Dempsey, Graham T.; Sun, Eileen; Zhuang, Xiaowei

2013-01-01

58

Intermolecular zirconium-catalyzed hydrophosphination of alkenes and dienes with primary phosphines.  

PubMed

Catalytic hydrophosphination of terminal alkenes and dienes with primary phosphines (RPH2; R = Cy, Ph) under mild conditions has been demonstrated using a zirconium complex, [?(5)-N,N,N,N,C-(Me3SiNCH2CH2)2NCH2CH2NSiMe2CH]Zr (1). Exclusively anti-Markovnikov functionalized products were observed, and the catalysis is selective for either the secondary or tertiary phosphine (i.e., double hydrophosphination) products, depending on reaction conditions. The utility of the secondary phosphine products as substrates for further elaboration was demonstrated with a platinum-catalyzed asymmetric alkylation reaction. PMID:24937212

Ghebreab, Michael B; Bange, Christine A; Waterman, Rory

2014-07-01

59

Manufacture of Thin-Film Photovoltaic Cells: Characterization and Management of Phosphine Hazards.  

National Technical Information Service (NTIS)

Phosphine is a highly toxic and flammable gas used in thin-film photovoltaic cell manufacturing. Its use can present serious occupational and public health hazards if appropriate prevention and control options are not effectively implemented. This report ...

V. M. Fthenakis P. D. Moskowitz

1986-01-01

60

Flammability Properties of Phosphine Oxide Copolymers and of Commodity Polymers with New Flame Retardant Additives.  

National Technical Information Service (NTIS)

Several different phosphine oxides, triphenylphosphine oxide, diphenylphosphine oxide, and trihydroxylpropylphosphine oxide, are added into nylon 6,6 by copolymerization and by blending. The flammability properties of these samples are measured in the Con...

I. Y. Wan J. E. McGrath J. W. Gilman T. Kashiwagi

1996-01-01

61

Features of hydroformylation in the presence of a rhodium complex with a macromolecular phosphine ligand  

Microsoft Academic Search

In the present paper a quantitative comparison is made of the catalytic activity and regioselectivity in 1-dodecene hydroformylation of complexes of rhodium with triphenylphosphine and with phosphinated polystyrene dissolved in the reaction medium. 22 refs., 4 figs., 2 tabs.

N. S. Imyanitov; S. B. Tupitsyn

1993-01-01

62

Features of hydroformylation in the presence of a rhodium complex with a macromolecular phosphine ligand  

SciTech Connect

In the present paper a quantitative comparison is made of the catalytic activity and regioselectivity in 1-dodecene hydroformylation of complexes of rhodium with triphenylphosphine and with phosphinated polystyrene dissolved in the reaction medium. 22 refs., 4 figs., 2 tabs.

Imyanitov, N.S.; Tupitsyn, S.B. [VNIINeftekhim, St Petersburg (Russian Federation)

1993-12-31

63

On the prebiotic potential of reduced oxidation state phosphorus: the H-phosphinate-pyruvate system.  

PubMed

H-Phosphinic acid and pyruvic acid, both plausible prebiotic chemicals, react selectively in water to build structural complexity including amide bond formation under remarkably mild conditions and oxidative coupling of P(1) compounds to condensed pyrophosphorus compounds. PMID:20386792

Bryant, David E; Marriott, Katie E R; Macgregor, Stuart A; Kilner, Colin; Pasek, Matthew A; Kee, Terence P

2010-06-01

64

New hydrogen-containing zirconium clusters with phosphine ligands  

Microsoft Academic Search

Reaction of ZrCl4 with 2 equiv. of HSnBu3 followed by addition of phosphines yields hexazirconium cluster compounds [Zr6Cl14H4(PR3)4] (2a: PR3 = PMe2Ph; 2b: PR3 = PEt2Pgh; 2c: PR3 = PEt3) and pentazirconium cluster compounds [Zr5Cl12H4(PR3)5] (3a:PR3 = PMe2Ph; 3c; PR3 = PEt2). Treatment of compound 2a with Na\\/Hg in the presence of PMe2Ph results in the formation [Zr6Cl12H2(PMe2Ph)6] (4a). When

Linfeng Chen; F. Albert Cotton

1997-01-01

65

Performance of phosphine in fumigation of bagged paddy rice in indoor and outdoor stores  

Microsoft Academic Search

Phosphine fumigation trials were carried out on bag-stacks of paddy rice to study the differences in gas loss rates and concentration–time (Ct) products achieved during the treatment of indoor and outdoor stacks. Stacks (89–132t) were fumigated singly under 250?m thick polyethylene sheeting, which was sealed with a double layer of sand-snakes to the concrete floor. Phosphine was applied as an

S. Rajendran; N. Muralidharan

2001-01-01

66

Preparation, characterization and catalytic hydroformylation properties of carbon nanotubes-supported Rh–phosphine catalyst  

Microsoft Academic Search

Two kinds of carbon nanotubes grown catalytically, as a novel material for catalyst carrier, were prepared and characterized. Propene hydroformylation catalyzed by the Rh–phosphine complex catalysts supported by carbon nanotubes was investigated, and compared to that catalyzed by the Rh–phosphine complex catalysts supported by SiO2 (a silica gel), TDX-601 (a carbon molecular sieve), AC (an active carbon), and GDX-102 (a

Yu Zhang; Hong-Bin Zhang; Guo-Dong Lin; Ping Chen; You-Zhu Yuan; K. R. Tsai

1999-01-01

67

Synthesis and characterisation of a new class of phosphine-phosphonite ferrocenediyl dinuclear rhodium complexes  

Microsoft Academic Search

We previously reported the easy access to mixed ferrocenediyl ligands bearing phosphine and phosphonite moieties. Using this strategy, a new enantiopure phosphine-menthylphosphonite ferrocenediyl has been synthesised. This mixed ligand leads to original unsymmetrical dinuclear rhodium coordination-complexes. One example of this new class of “quasi-close bridging A frame” dinuclear rhodium complexes, fully characterised by multinuclear 1H, 13C, 31P and 103Rh NMR

Jean-Cyrille Hierso; Francis Lacassin; Roland Broussier; Régine Amardeil; Philippe Meunier

2004-01-01

68

Measurement of solubilities for rhodium complexes and phosphine ligands in supercritical carbon dioxide  

Microsoft Academic Search

The solubilities of phosphine ligands and rhodium (Rh) complexes in supercritical carbon dioxide were measured with Fourier transform infrared (FT-IR) spectroscopy at 320 and 333K and several pressures. Triphenylphosphine (TPP) and tris(p-trifluoromethylphenyl)-phosphine (TTFMPP) were selected as ligands for the Rh complex. The solubilities of the fluorinated ligands and complexes were compared with those of the non-fluorinated compounds. The solubilities of

Yusuke Shimoyama; Masanori Sonoda; Kaoru Miyazaki; Hidenori Higashi; Yoshio Iwai; Yasuhiko Arai

2008-01-01

69

Asymmetric Synthesis of Spiropyrazolones through Phosphine-Catalyzed [4+1] Annulation.  

PubMed

An enantioselective synthesis of spiropyrazolones from allenoate-derived MBH acetates and pyrazolones through a phosphine-mediated [4+1] annulation process has been developed. Spiropyrazolones were readily prepared in good chemical yields and good to high enantioselectivities. This is the first asymmetric example in which ?-substituted allenoates were utilized as a C4 synthon for phosphine-catalyzed [4+1] annulation. PMID:24737675

Han, Xiaoyu; Yao, Weijun; Wang, Tianli; Tan, Yong Ren; Yan, Ziyu; Kwiatkowski, Jacek; Lu, Yixin

2014-05-26

70

Oxidative hydroxylation of phosphine in aqueous alcohol solutions of p-benzoquinone  

NASA Astrophysics Data System (ADS)

The oxidation of phosphine in aqueous alcohol solution of benzoquinone in the presence of iodide ions is studied. Kinetic measurements, redox potentiometry, and gas chromatography are used to determine the kinetic regularities of the oxidative hydroxylation of phosphine, and a single-stage redox mechanism is proposed for this reaction. It is found that the iodine resulting from the oxidation of I- ions by quinone is the reagent responsible for the formation of phosphorus-containing products.

Polimbetova, G. S.; Borangazieva, A. K.; Ibraimova, Zh. U.; Ergozhin, E. E.; Mukhitdinova, B. A.

2014-05-01

71

Mechanism of thermal decomposition of trans-diethylbis(tertiary phosphine)palladium(II). Steric effects of tertiary phosphine ligands on the stability of diethylpalladium complexes  

SciTech Connect

trans-(PdR'/sub 2/(PR/sub 3/)/sub 2/) with a series of alkyl groups and tertiary phosphine ligands of various steric bulkiness (R' = Et, PR/sub 3/ = PMe/sub 2/Ph, PEt/sub 3/, PEt/sub 2/Ph, PMePh/sub 2/, PEtPh/sub 2/; R' = Pr, Bu, PR/sub 3/ = PMe/sub 2/Ph) are thermolyzed in solution by ..beta..-elimination processes liberating alkane and alkene in a 1:1 ratio. Kinetic studies on thermolysis of trans-(PdEt/sub 2/(PR/sub 3/)/sub 2/) revealed that they decompose obeying the first-order rate law with respect to the concentration of the palladium complexes. Thermolysis predominantly proceeds from the four-coordinated complex without dissociation of the tertiary phosphine ligand. The minor parallel thermolysis pathway involving the dissociation of the phosphine is completely blocked by addition of the phosphine. Activation enthalpies for thermolysis of the ethylpalladium complexes having various steric bulkiness were virtually constant in the range of 26.0 +- 1.0 kcal/mol whereas activation entropies showed considerable variation with increasing bulkiness of the phosphine. Thermolysis of trans-(Pd(CH/sub 2/CD/sub 3/)/sub 2/(PMePh/sub 2/)/sub 2/) cleanly liberated CH/sub 2/==CD/sub 2/ and CH/sub 2/DCD/sub 3/ with a small isotope effect (k/sub H//k/sub D/ = 1.4 +- 0.1). The kinetic results together with examination of the molecular model suggest that the interaction between the bulky phosphine ligands and the ethyl groups causes the destabilization of the Pd-Et bonds. A thermolysis mechanism consistent with the kinetic results assuming an activation state distorted from the square-planar ground state is proposed. 6 figures, 5 tables.

Ozawa, F.; Ito, T.; Yamamoto, A.

1980-10-08

72

Comparison of structure and reactivity of phosphine-amido and hemilabile phosphine-amine chelates of rhodium.  

PubMed

A series of mono- and binuclear rhodium(I) complexes bearing ortho-phosphinoanilido and ortho-phosphinoaniline ligands has been synthesized. Reactions of the protic monophosphinoanilines, Ph(2)PAr or PhPAr(2) (Ar = o-C(6)H(4)NHMe), with 0.5 equiv of [Rh(?-OMe)(COD)](2) result in the formation of the neutral amido complexes, [Rh(COD)(P,N-Ph(2)PAr(-))] or [Rh(COD)(P,N-PhP(Ar(-))Ar)] (Ar(-) = o-C(6)H(4)NMe(-)), respectively, through stoichiometrically controlled deprotonation of an amine by the internal methoxide ion. Similarly, the binuclear complex, [Rh(2)(COD)(2)(?-P,N,P',N'-mapm(2-))] (mapm(2-) = Ar(Ar(-))PCH(2)P(Ar(-))Ar), can be prepared by reaction of the protic diphosphinoaniline, mapm (Ar(2)PCH(2)PAr(2)), with 1 equiv of [Rh(?-OMe)(COD)](2). An analogous series of hemilabile phosphine-amine compounds can be generated by reactions of monophosphinoanilines, Ph(2)PAr' or PhPAr'(2) (Ar' = o-C(6)H(4)NMe(2)), with 1 equiv of [Rh(NBD)(2)][BF(4)] to generate [Rh(NBD)(P,N-Ph(2)PAr')][BF(4)] or [Rh(NBD)(P,N-PhPAr'(2))][BF(4)], respectively, or by reactions of diphosphinoanilines, mapm or dmapm (Ar'(2)PCH(2)PAr'(2)), with 2 equiv of the rhodium precursor to generate [Rh(2)(NBD)(2)(?-P,N,P',N'-mapm)][BF(4)](2) or [Rh(2)(NBD)(2)(?-P,N,P',N'-dmapm)][BF(4)](2), respectively. Displacement of the diolefin from [Rh(COD)(P,N-Ph(2)PAr(-))] by 1,2-bis(diphenylphosphino)ethane (dppe) yields [Rh(P,P'-dppe)(P,N-Ph(2)PAr(-))] which, while unreactive to H(2), reacts readily and irreversibly with oxygen to form the peroxo complex, [RhO(2)(P,P'-dppe)(P,N-Ph(2)PAr(-))], and with iodomethane to yield [RhI(CH(3))(P,P'-dppe)(P,N-Ph(2)PAr(-))]. Hemilabile phosphine-amine compounds can also be prepared by reactions of [Rh(P,P'-dppe)(P,N-Ph(2)PAr(-))] with Me(3)OBF(4) or HBF(4)·Et(2)O, resulting in (thermodynamic) additions at nitrogen to form [Rh(P,P'-dppe)(P,N-Ph(2)PAr')][BF(4)] or [Rh(P,P'-dppe)(P,N-Ph(2)PAr)][BF(4)], respectively. The nonlabile phosphine-amido and hemilabile phosphine-amine complexes were tested as catalysts for the silylation of styrene. The amido species do not require the use of solvents in reaction media, can be easily removed from product mixtures by protonation, and appear to be more active than their hemilabile, cationic congeners. Reactions catalyzed by either amido or amine complexes favor dehydrogenative silylation in the presence of excess olefin, showing modest selectivities for a single vinylsilane product. The binuclear complexes, which were prepared in an effort to explore possible catalytic enhancements of reactivity due to metal-metal cooperativity, are in fact somewhat less active than mononuclear species, discounting this possibility. PMID:21591636

Hounjet, Lindsay J; McDonald, Robert; Ferguson, Michael J; Cowie, Martin

2011-06-20

73

A novel tridentate bis(phosphinic acid)phosphine oxide based europium(III)-selective Nafion membrane luminescent sensor.  

PubMed

A new europium(III) membrane luminescent sensor based on a new tridentate bis(phosphinic acid)phosphine oxide (3) system has been developed. The synthesis of this new ligand is described and its full characterization by NMR, IR and elemental analyses is provided. The luminescent complex formed between europium(III) chloride and ligand 3 was evaluated in solution, observing that its spectroscopic and chemical characteristics are excellent for measuring in polymer inclusion membranes. Included in a Nafion membrane, all the parameters (ligand and ionic additives) that can affect the sensitivity and selectivity of the sensing membrane as well as the instrumental conditions were carefully optimized. The best luminescence signal (?exc = 229.06 nm and ?em = 616.02 nm) was exhibited by the sensing film having a Nafion?:?ligand composition of 262.3?:?0.6 mg mL(-1). The membrane sensor showed a short response time (t95 = 5.0 ± 0.2 min) and an optimum working pH of 5.0 (25 mM acetate buffer solution). The membrane sensor manifested a good selectivity toward europium(III) ions with respect to other trivalent metals (iron, chromium and aluminium) and lanthanide(III) ions (lanthanum, samarium, terbium and ytterbium), although a small positive interference of terbium(III) ions was observed. It provided a linear range from 1.9 × 10(-8) to 5.0 × 10(-6) M with a very low detection limit (5.8 × 10(-9) M) and sensitivity (8.57 × 10(-7) a.u. per M). The applicability of this sensing film has been demonstrated by analyzing different kinds of spiked water samples obtaining recovery percentages of 95-97%. PMID:23967443

Sainz-Gonzalo, F J; Popovici, C; Casimiro, M; Raya-Barón, A; López-Ortiz, F; Fernández, I; Fernández-Sánchez, J F; Fernández-Gutiérrez, A

2013-10-21

74

A novel family of (1-aminoalkyl)(trifluoromethyl)- and -(difluoromethyl)phosphinic acids - analogues of ?-amino acids.  

PubMed

A series of novel (1-aminoalkyl)(trifluoromethyl)- and -(difluoromethyl)phosphinic acids - analogues of proteinogenic and nonproteinogenic ?-amino acids were prepared. The synthetic methodology was based on nucleophilic addition of (trifluoromethyl)phosphinic acid or (difluoromethyl)phosphinic acid or its ethyl ester to substrates with C=N or activated C=C double bonds. Analogues of glycine, phenylglycine, alanine, valine, proline, aminomalonic and aspartic acids were thus prepared. Three-component one-pot reactions of (trifluoromethyl)phosphinic acid and dibenzylamine with aldehydes were also tested to prepare the title compounds. PMID:24778725

Pavlenko, Natalia V; Oos, Tatiana I; Yagupolskii, Yurii L; Gerus, Igor I; Doeller, Uwe; Willms, Lothar

2014-01-01

75

A one-pot O-phosphinative Passerini/Pudovik reaction: efficient synthesis of highly functionalized ?-(phosphinyloxy)amide derivatives.  

PubMed

A one-pot O-phosphinative Passerini/Pudovik reaction has been developed, based on reacting aldehydes, isocyanides, and phosphinic acids followed by the addition of second aldehydes to form the corresponding ?-(phosphinyloxy)amide derivatives. This is the first reported instance of a Passerini-type, isocyanide-based multicomponent reaction using a phosphinic acid instead of a carboxylic acid. The nucleophilicity of the phosphinate group allows a subsequent catalytic Pudovik-type reaction, affording the highly functionalized ?-(phosphinyloxy)amide derivative in high yield. A wide range of aldehydes and isocyanides are applicable to this reaction. PMID:24615915

Soeta, Takahiro; Matsuzaki, Syunsuke; Ukaji, Yutaka

2014-04-22

76

Performance of phosphine in fumigation of bagged paddy rice in indoor and outdoor stores.  

PubMed

Phosphine fumigation trials were carried out on bag-stacks of paddy rice to study the differences in gas loss rates and concentration-time (Ct) products achieved during the treatment of indoor and outdoor stacks. Stacks (89-132t) were fumigated singly under 250&mgr;m thick polyethylene sheeting, which was sealed with a double layer of sand-snakes to the concrete floor. Phosphine was applied as an aluminium phosphide formulation and the fumigations continued for 7 days. In the first experiment, stacks of paddy rice with moisture contents ranging from 12.2 to 13.7% were held in either indoor or in outdoor storage and subjected to fumigation at the rate of 2, 3 or 4g of phosphine/tonne. The outdoor stacks held relatively low levels of phosphine with Ct products for the indoor stacks of 135, 171 and 294gh/m(3), respectively, whilst the corresponding values for the outdoor stacks were 70, 85 and 166gh/m(3) only. The average gas loss rate was 14.5% per day for the indoor stacks and 29.5% for the outdoor stacks. In the second experiment, old stacks of paddy rice inside a godown, one each with grains at 8.8 and 9.8% moisture content, were fumigated at 3g phosphine/tonne. Release of phosphine was delayed and fumigant sorption was less and therefore higher Ct products of 204 and 216gh/m(3) were achieved. In the stacks built outdoors, the resident infestations of Rhyzopertha dominica, Cryptolestes sp. and Oryzaephilus surinamensis were completely controlled despite lower Ct products. On the other hand, in the stacks of old paddy, R. dominica survived the treatment. Subsequent testing showed that the population had a degree of resistance to phosphine. PMID:11463397

Rajendran, S; Muralidharan, N

2001-10-01

77

Synthesis and Coordination Chemistry of Phosphine Oxide Decorated Dibenzofuran Platforms  

SciTech Connect

A four-step synthesis for 4,6-bis(diphenylphosphinoylmethyl)dibenzofuran (4) from dibenzofuran and a two-step synthesis for 4,6-bis(diphenylphosphinoyl)dibenzofuran (5) are reported along with coordination chemistry of 4 with In(III), La(III), Pr(III), Nd(III), Er(III), and Pu(IV) and of 5 with Er(III). Crystal structure determinations for the ligands, 4 {center_dot} CH{sub 3}OH and 5, the 1:1 complexes [In(4)(NO{sub 3}){sub 3}], [Pr(4)(NO{sub 3}){sub 3}(CH{sub 3}CN)] {center_dot} 0.5CH{sub 3}CN, [Er(4)(NO{sub 3}){sub 3}(CH{sub 3}CN)] {center_dot} CH{sub 3}CN, [Pu(4)Cl4] {center_dot} THF and the 2:1 complex [Nd(4){sub 2}(NO{sub 3}){sub 2}]{sub 2}(NO{sub 3}){sub 2} {center_dot} (H{sub 2}O) {center_dot} 4(CH{sub 3}OH) are described. In these complexes, ligand 4 coordinates in a bidentate POP{prime}O{prime} mode via the two phosphine oxide O-atoms. The dibenzofuran ring O-atom points toward the central metal cations, but in every case it is more than 4 {angstrom} from the metal. A similar bidentate POP{prime}O{prime} chelate structure is formed between 5 and Er(III) in the complex, {l_brace}[Er(5){sub 2}(NO{sub 3}){sub 2}](NO{sub 3}) {center_dot} 4(CH{sub 3}OH){r_brace}0.5, although the nonbonded Er{hor_ellipsis} O{sub furan} distance is reduced to 3.6 {angstrom}. The observed bidentate chelation modes for 4 and 5 are consistent with results from molecular mechanics computations. The solvent extraction performance of 4 and 5 in 1,2-dichloroethane for Eu(III) and Am(III) in nitric acid solutions is described and compared against the extraction behavior of n-octyl(phenyl)-N,N-diisobutylcarbamoylmethyl phosphine oxide (O{Phi}DiBCMPO) measured under identical conditions.

Rosario-Amorin, Daniel [University of New Mexico, Albuquerque; Duesler, Eileen N. [University of New Mexico, Albuquerque; Paine, Robert T. [University of New Mexico, Albuquerque; Hay, Benjamin [ORNL; Delmau, Laetitia Helene [ORNL; Reilly, Sean D. [Los Alamos National Laboratory (LANL); Gaunt, Andrew J. [Los Alamos National Laboratory (LANL); Scott, Brian L. [Los Alamos National Laboratory (LANL)

2012-01-01

78

Synthesis of p-aminophenyl aryl H-phosphinic acids and esters via cross-coupling reactions: elaboration to phosphinic acid pseudopeptide analogues of pteroyl glutamic acid and related antifolates.  

PubMed

The synthesis of suitably protected p-aminophenyl H-phosphinic acids and esters from the corresponding para-substituted aryl halides has been accomplished via the Pd-catalyzed cross-coupling reaction of anilinium hypophosphite, either in the absence or presence of a tetraalkyl orthosilicate, to provide the free H-phosphinic acid or the corresponding ester, respectively. Subsequent conjugate addition of either a PIII species or phosphorus anion, generated in situ from either the free H-phosphinic acid or ester, to a 2-methylene glutaric acid ester provided the aryl phosphinic acid analogue of p-aminobenzoyl glutamic acid. Alkylation of these suitably protected p-aminophenyl phosphinic acid esters with a 6-(bromomethyl)pteridine or the corresponding (bromomethyl)pyridopyrmidine, followed by hydrolytic removal of protecting groups, provided the target aryl phosphinic acid analogues of folic acid and related antifolates. Alternatively, for the synthesis of the folate or 5-deazafolate analogues on a slightly larger scale, reductive amination with either N2-acetyl or N2-pivaloyl-6-formylpterin or the corresponding formylpyridopyrmidine and the same suitably protected p-aminophenyl phosphinic acid esters, followed by removal of protecting groups, is preferred. In the course of this research, it was observed that the nucleophilicity of both the aniline nitrogen and various PIII species derived from p-aminophenyl phosphinic acid derivatives is significantly reduced compared to that of the unsubstituted counterpart. PMID:17602593

Yang, Yonghong; Coward, James K

2007-07-20

79

Comparative effects of gamma irradiation and phosphine fumigation on the quality of white ginseng  

NASA Astrophysics Data System (ADS)

The hygienic, physicochemical, and organoleptic qualities of white ginseng were monitored during 6 months under accelerated conditions (40°C, 90% r.h.) by observing its microbial populations, disinfestation, and some quality attributes following either gamma irradiation at 2.5-10 kGy or commercial phosphine (PH 3) fumigation. In a comparative study, both treatments were found to be effective for disinfecting the stored samples. Phosphine showed no appreciable decontaminating effects on microorganisms contaminated including coliforms, while 5 kGy irradiation was sufficient to control all microorganisms related to the quality of the packed samples. Irradiation at 5 kGy caused negligible changes in physicochemical attributes of the samples, such as ginsenosides, amino acids, fatty acids, and organoleptic properties, whereas phosphine fumigation was found detrimental to sensory flavor ( P<0.01). Quality deterioration occurred in the commercially-packed samples was in the following order: the control, 10 kGy-, phosphine-, and 2.5-5 kGy-treated samples. Accordingly, irradiation at <5 kGy was found to be an effective alternative to phosphine fumigation for white ginseng.

Kwon, J.-H. J.-H.; Byun, M.-W. M.-W.; Kim, K.-S. K.-S.; Kang, I.-J. I.-J.

2000-03-01

80

ATP-dependent ligases in trypanothione biosynthesis - kinetics of catalysis and inhibition by phosphinic acid pseudopeptides  

PubMed Central

Glutathionylspermidine is an intermediate formed in the biosynthesis of trypanothione, an essential metabolite in defence against chemical and oxidative stress in the Kinetoplastida. The kinetic mechanism for glutathionylspermidine synthetase (EC 6.3.1.8) from Crithidia fasciculata (CfGspS) obeys a rapid equilibrium random ter-ter model with kinetic constants KGSH = 609 ?m, KSpd = 157 ?m and KATP = 215 ?m. Phosphonate and phosphinate analogues of glutathionylspermidine, previously shown to be potent inhibitors of GspS from Escherichia coli, are equally potent against CfGspS. The tetrahedral phosphonate acts as a simple ground state analogue of glutathione (GSH) (Ki ? 156 ?m), whereas the phosphinate behaves as a stable mimic of the postulated unstable tetrahedral intermediate. Kinetic studies showed that the phosphinate behaves as a slow-binding bisubstrate inhibitor [competitive with respect to GSH and spermidine (Spd)] with rate constants k3 (on rate) = 6.98 × 104 m?1·s?1 and k4 (off rate) = 1.3 × 10?3 s?1, providing a dissociation constant Ki = 18.6 nm. The phosphinate analogue also inhibited recombinant trypanothione synthetase (EC 6.3.1.9) from C. fasciculata, Leishmania major, Trypanosoma cruzi and Trypanosoma brucei with Kiapp values 20–40-fold greater than that of CfGspS. This phosphinate analogue remains the most potent enzyme inhibitor identified to date, and represents a good starting point for drug discovery for trypanosomiasis and leishmaniasis.

Oza, Sandra L; Chen, Shoujun; Wyllie, Susan; Coward, James K; Fairlamb, Alan H

2008-01-01

81

Rhodium Phosphine-?-Arene Intermediates in the Hydroamination of Alkenes  

PubMed Central

A detailed mechanistic study of the intramolecular hydroamination of alkenes with amines catalyzed by rhodium complexes of a biaryldialkylphosphine are reported. The active catalyst is shown to contain the phosphine ligand bound in a ?1, ?6 form in which the arene is ?-bound to rhodium. Addition of deuterated amine to an internal olefin showed that the reaction occurs by trans addition of the N-H bond across the C=C bond, and this stereochemistry implies that the reaction occurs by nucleophilic attack of the amine on a coordinated alkene. Indeed, the cationic rhodium fragment binds the alkene over the secondary amine, and the olefin complex was shown to be the catalyst resting state. The reaction was zero-order in substrate, when the concentration of olefin was high, and a primary isotope effect was observed. The primary isotope effect, in combination with the observation of the alkene complex as the resting state, implies that nucleophilic attack of the amine on the alkene is reversible and is followed by turnover-limiting protonation. This mechanism constitutes an unusual pathway for rhodium-catalyzed additions to alkenes and is more closely related to the mechanism for palladium-catalyzed addition of amide N-H bonds to alkenes.

Liu, Zhijian; Yamamichi, Hideaki; Madrahimov, Sherzod T.; Hartwig, John F.

2011-01-01

82

Rhodium phosphine-?-arene intermediates in the hydroamination of alkenes.  

PubMed

A detailed mechanistic study of the intramolecular hydroamination of alkenes with amines catalyzed by rhodium complexes of a biaryldialkylphosphine is reported. The active catalyst is shown to contain the phosphine ligand bound in a ?(1), ?(6) form in which the arene is ?-bound to rhodium. Addition of deuterated amine to an internal olefin showed that the reaction occurs by trans addition of the N-H bond across the C?C bond, and this stereochemistry implies that the reaction occurs by nucleophilic attack of the amine on a coordinated alkene. Indeed, the cationic rhodium fragment binds the alkene over the secondary amine, and the olefin complex was shown to be the catalyst resting state. The reaction was zero-order in substrate, when the concentration of olefin was high, and a primary isotope effect was observed. The primary isotope effect, in combination with the observation of the alkene complex as the resting state, implies that nucleophilic attack of the amine on the alkene is reversible and is followed by turnover-limiting protonation. This mechanism constitutes an unusual pathway for rhodium-catalyzed additions to alkenes and is more closely related to the mechanism for palladium-catalyzed addition of amide N-H bonds to alkenes. PMID:21309512

Liu, Zhijian; Yamamichi, Hideaki; Madrahimov, Sherzod T; Hartwig, John F

2011-03-01

83

Phosphine-catalyzed sequential annulation domino reaction: rapid construction of bicyclo[4.1.0]heptene skeletons.  

PubMed

A convenient and efficient phosphine-catalyzed sequential annulation domino reaction between dienic sulfones and MBH carbonates has been developed. In the presence of 20 mol% of tris(4-fluorophenyl)phosphine, functionalized bicyclo[4.1.0]heptenes were prepared in excellent yields and stereoselectivities under mild conditions. PMID:24733288

Zheng, Jie; Huang, You; Li, Zhengming

2014-06-01

84

Rapid and selective nitroxyl (HNO) trapping by phosphines: kinetics and new aqueous ligations for HNO detection and quantitation  

PubMed Central

Recent studies distinguish the biological and pharmacological effects of nitroxyl (HNO) from its oxidized/deprotonated product nitric oxide (NO), but lack of HNO detection methods limits understanding its in vivo mechanisms and the identification of endogenous sources. We previously demonstrated that reaction of HNO with triarylphosphines provides aza-ylides and HNO-derived amides, which may serve as stable HNO biomarkers. We now report a kinetic analysis for the trapping of HNO by phosphines, ligations of enzyme-generated HNO, and compatibility studies illustrating the selectivity of phosphines for HNO over other physiologically relevant nitrogen oxides. Quantification of HNO using phosphines is demonstrated using an HPLC-based assay and ligations of phosphine carbamates generate HNO-derived ureas. These results further demonstrate the potential of phosphine probes for reliable biological detection and quantification of HNO.

Reisz, Julie A.; Zink, Charles N.; King, S. Bruce

2011-01-01

85

Steroid phosphorus compounds. V--Mass spectrometry of phosphinic esters of monohydroxy steroids.  

PubMed

The mass spectra of the dimethylphosphinic, dimethylthiophosphinic and dimethylphosphinous ester derivatives of several monohydroxy steroids are reported. The fragmentations of the derivatized steroids largely depend on the nature of the phosphorus-containing ester group. Phenolic ester derivatives exhibit the base peak at the molecular ion, whereas the spectra of the secondary phosphinic esters are dominated by very intense protonated phosphinic acid ions [Me2P(XH)(OH)]+ at m/e 95 (X =O) or at m/e 111 (x = s). The present results also indicate the low ionization potential for the phosphinic ester group. Due to their good gas chromatographic properties, these steroid derivatives appear to be particularly suitable for gas chromatographic mass spectrometric analysis of biochemical materials. PMID:131590

Jacob, K; Vogt, W; Knedel, M; Scháfer, W

1976-04-01

86

A Bis(phosphine)-Modified Peptide Ligand for Stable and Luminescent Quantum Dots in Aqueous Media  

PubMed Central

We describe a new class of ligands for semiconductor nanoparticles (quantum dots = QDs), which bind well and allow for their facile dissolution in aqueous solution. As a proof of principle, we have designed and synthesized a novel bis(phosphine)-modified peptide (BPMP) and shown that it has the ability to solubilize quantum dots in aqueous media. We further showed that the corresponding phosphine oxide derivatives of these new ligands are less good at solubilizing the quantum dots. These new bis(phosphine)-modified peptide ligands are easy to prepare and may well replace thiol-containing binding sequences in functionalized peptides for quantum dot coating, potentially resulting in quantum dots with higher quantum yields.

Jung, Michael E.; Trzoss, Michael; Tsay, James M.; Weiss, Shimon

2014-01-01

87

The Vertical Structure and Phosphine Distribution on Saturn as Determined by Cassini/VIMS  

NASA Astrophysics Data System (ADS)

We present the preliminary results of our study on the variations of (1) the vertical aerosol layer structure and (2) the phosphine (PH3) distribution on Saturn, utilizing Cassini/VIMS spectral imagery. From the Cassini/VIMS infrared channel spectral data of Saturn acquired in 2004, we sample a dozen pixels at each of the following four latitudes (-10, -27, -47, and -73 degree) to create a set of multi-spectral center-limb profiles for our radiative transfer analysis. We first fit the NIR methane band spectra to determine the altitude of the upper tropospheric haze at the four latitudes, using the newest CH4 near-infrared correlated-k coefficients (Irwin et al. 2006, Icarus, 181, 309-319) and a multi-layer model. This latitudinal variation in the haze altitude is an important clue to unveil Saturn's global climate system. On that basis, we fit the phosphine band spectrum near 3 micron to constrain the phosphine column abundance, using recently published PH3 absorption data sets (Temma et al. 2006, JGR, accepted). Since phosphine is a disequilibrium species in Saturn's upper atmosphere, its increase suggests enhanced convective activity from the deep interior. We thus map the latitudinal phosphine distribution on Saturn, including the analysis of the south polar region where an anomalously strong phosphine absorption was reported (Baines et al. 2005, Earth, Moon, and Planets, 96, 119--147). This work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. The first author of this presentation is supported by the NASA Postdoctoral Fellowship at the Jet Propulsion Laboratory.

Temma, Takafumi; Baines, K. H.; Momary, T. W.; Cassini/VIMS Team

2006-09-01

88

The Vertical Structure and Phosphine Distribution on Saturn as Determined by Cassini/VIMS  

NASA Astrophysics Data System (ADS)

We present the preliminary results of our study on the variations of (1) the vertical aerosol layer structure and (2) the phosphine (PH3) distribution on Saturn, utilizing Cassini/VIMS spectral imagery. From the Cassini/VIMS infrared channel spectral data of Saturn acquired in 2004, we sample a dozen pixels at each of the following four latitudes (-10, -27, -47, and -73 degree) to create a set of multi-spectral center-limb profiles for our radiative transfer analysis. We first fit the NIR methane band spectra to determine the altitude of the upper tropospheric haze at the four latitudes, using the newest CH4 near-infrared correlated-k coefficients (Irwin et al. 2006, Icarus, 181, 309-319) and a multi-layer model. This latitudinal variation in the haze altitude is an important clue to unveil Saturn's global climate system. On that basis, we fit the phosphine band spectrum near 3 micron to constrain the phosphine column abundance, using recently published PH3 absorption data sets (Temma et al. 2006, JGR, accepted). Since phosphine is a disequilibrium species in Saturn's upper atmosphere, its increase suggests enhanced convective activity from the deep interior. We thus map the latitudinal phosphine distribution on Saturn, including the analysis of the south polar region where an anomalously strong phosphine absorption was reported (Baines et al. 2005, Earth, Moon, and Planets, 96, 119--147). This work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. The first author of this presentation is supported by the NASA Postdoctoral Fellowship at the Jet Propulsion Laboratory.

Temma, T.; Baines, K. H.; Momary, T. W.

2006-12-01

89

Phosphine resistance in Tribolium castaneum and Rhyzopertha dominica from stored wheat in Oklahoma.  

PubMed

Phosphine gas, or hydrogen phosphide (PH3), is the most common insecticide applied to durable stored products worldwide and is routinely used in the United States for treatment of bulk-stored cereal grains and other durable stored products. Research from the late 1980s revealed low frequencies of resistance to various residual grain protectant insecticides and to phosphine in grain insect species collected in Oklahoma. The present work, which used the same previously established discriminating dose bioassays for phosphine toxicity as in the earlier study, evaluated adults of nine different populations of red flour beetle, Tribolium castaneum (Herbst), and five populations of lesser grain borer, Rhyzopertha dominica (F.) collected from different geographic locations in Oklahoma. One additional population for each species was a laboratory susceptible strain. Discriminating dose assays determined eight out of the nine T. castaneum populations, and all five populations of R. dominica, contained phosphine-resistant individuals, and highest resistance frequencies were 94 and 98%, respectively. Dose-response bioassays and logit analyses determined that LC99 values were approximately 3 ppm for susceptible and 377 ppm for resistant T. castaneum, and approximately 2 ppm for susceptible and 3,430 ppm for resistant R. dominica. The most resistant T. castaneum population was 119-fold more resistant than the susceptible strain and the most resistant R. dominica population was over 1,500-fold more resistant. Results suggest a substantial increase in phosphine resistance in these major stored-wheat pests in the past 21 yr, and these levels of resistance to phosphine approach those reported for other stored-grain pest species in other countries. PMID:22928286

Opit, G P; Phillips, T W; Aikins, M J; Hasan, M M

2012-08-01

90

198Au-labeled hydroxymethyl phosphines as models for potential therapeutic pharmaceuticals  

Microsoft Academic Search

The development of novel gold-198 complexes with water-soluble phosphines is reported. A series of cationic and hydrophilic 198Au complexes containing the ligands tris(hydroxymethyl)phosphine (THP, 1) 1,2-bis[bis(hydroxymethyl)phosphino]benzene (HMPB, 2), and 1,2-bis[bis(hydroxymethyl)phosphino]ethane (HMPE, 3) were prepared and evaluated as models for potential gold-199 radiopharmaceuticals. The 198Au complexes were formed in high radiochemical purity by simply mixing H198AuCl4 with the respective ligand. The

D. E Berning; K. V Katti; W. A Volkert; C. J Higginbotham; A. R Ketring

1998-01-01

91

Copper(I) complexes with bipyridyl and phosphine ligands: a systematic study.  

PubMed

Phosphorescent copper(I) complexes carrying 2,2'-bipyridyl derivatives and phosphine ligands have been prepared and fully characterised. The role of the bipyridyl as well as the phosphine ligands in defining the optical, as well as the chemical properties of the complexes, are discussed. The light emission of these complexes is investigated as a function of the molecular geometry: rigid complexes with restricted freedom to rearrange in the excited state are found to show a quantum yield of phosphorescence one order of magnitude higher than those complexes with no steric constraint. The complexes have been extruded in a polymer matrix as a proof of principle of their processability. PMID:22677980

Andrés-Tomé, Inmaculada; Fyson, John; Dias, Fernando Baiao; Monkman, Andy P; Iacobellis, Giuliano; Coppo, Paolo

2012-07-28

92

Synthesis and characterization of rhodium complexes with phosphine-stabilized germylenes.  

PubMed

The reaction of phosphine-stabilized germylenes (1a,b) with dimer complex [Rh(2)(?-Cl)(2)(COD)(2)] leads to the corresponding phosphine-germylene-Rh(I) complexes (2a,b). Interestingly, the stability of these complexes depends strongly on the nature of the substituent of the germylene fragment. Indeed, the complex (2a) with the chloro-germylene ligand isomerizes into a metallacycle rhodium complex (3a) via germylene insertion into the Rh-Cl bond, while the complex with the phenyl-substituted germylene (2b) was isolated and represents the first stable Rh(I)-germylene complex with a Rh-Cl bond. PMID:22831875

García, Juan M; Ocando-Mavárez, Edgar; Kato, Tsuyoshi; Coll, David Santiago; Briceño, Alexander; Saffon-Merceron, Nathalie; Baceiredo, Antoine

2012-08-01

93

Adducts of Rh2[MTPA]4 with some phosphine chalcogenides: nature of binding and ligand exchange.  

PubMed

Adducts of four phosphine chalcogenides with the chiral dirhodium complex ([Rh-Rh]) were investigated by variable-temperature 1H and 31P NMR spectroscopy in order to compare their properties as axial ligands. Whereas the selenide (1) and the sulfide (2) are strong ligands with electrostatic attraction and, in addition, a significant orbital (HOMO-LUMO) interaction, the phosphine oxide compounds (P=O) bind primarily via electrostatic attraction and are relatively weak donors. Moreover, the overall bond strength in these adducts depends on steric congestion around the P=O group. PMID:15181630

Gáti, Tamás; Simon, András; Tóth, Gábor; Magiera, Damian; Moeller, Stefan; Duddeck, Helmut

2004-07-01

94

Enantioselective synthesis of H-phosphinic acids bearing natural amino acid residues.  

PubMed

The first systematic study on the asymmetric synthesis of H-phosphinic acids bearing natural protein amino acid residues was reported on the basis of the asymmetric addition of ethyl diethoxymethylphosphinate to N-tert-butanesulfinyl imines. Good yields and moderate to high enantioselectivities were obtained. Reliable methods were developed for the elucidation of the stereochemistry of these phosphinic acids and derivatives thereof. The transformation of the side chains of these analogues was studied. Methods for the conversion of the ?-aminophosphinates to oligopetides were reported. PMID:23772951

Yao, Qiuli; Yuan, Chengye

2013-07-19

95

Suppressing triplet state extension for highly efficient ambipolar phosphine oxide host materials in blue PHOLEDs.  

PubMed

A series of phosphine oxide hosts were constructed to investigate the influence of the triplet state extension in hosts on electrophosphorescence, in which DPESPOPhCz with the carbazolyl-localized triplet state endowed its blue-emitting PHOLEDs with favourable performance, including an external quantum efficiency more than 13%. PMID:24473273

Han, Chunmiao; Zhu, Liping; Zhao, Fangchao; Zhang, Zhen; Wang, Jianzhe; Deng, Zhaopeng; Xu, Hui; Li, Jing; Ma, Dongge; Yan, Pengfei

2014-03-11

96

Phosphine-catalyzed annulation of ethyl (arylimino)acetates: synthesis of highly functionalized oxoimidazolidines.  

PubMed

This paper describes an unexpected and novel nucleophilic phosphine-catalyzed annulation of ethyl (arylimino)acetates to give polysubstituted oxoimidazolidine derivatives in moderate to good yields from simple and easily available starting materials under mild conditions. In this reaction, the addition of methyl vinyl ketone (MVK) is essential to induce the formation of oxoimidazolidines. PMID:18931765

Ma, Guang-Ning; Wang, Fei-Jun; Gao, Jun; Shi, Min

2008-10-28

97

Borane Complexes of the H3PO2 P(III) Tautomer: Useful Phosphinate Equivalents  

PubMed Central

The preparation and reactivity of novel (R1O)(R2O)P(BH3)H [R1, R2 = Et, TIPS] synthons is investigated. The direct alkylation of these compounds with lithium hexamethyldisilazide (LiHMDS) and various electrophiles, provided new series of phosphonite-borane complexes, which can be converted into H-phosphinates and boranophosphonates.

Belabassi, Yamina; Antczak, Monika I.; Tellez, Jennifer

2008-01-01

98

Phosphine-initiated domino reaction: a convenient method for the preparation of spirocyclopentanones.  

PubMed

An efficient synthetic approach has been developed for the construction of the spirocyclopentanone skeleton via a phosphine-catalyzed [3+2] annulation reaction. With this novel and economical protocol, various quaternary carbon-centered spirocyclopentanones could be readily obtained. PMID:24678009

Liang, Ling; Li, Erqing; Xie, Peizhong; Huang, You

2014-05-01

99

High temperature partition functions and thermodynamic data for ammonia and phosphine  

NASA Astrophysics Data System (ADS)

The total internal partition function of ammonia (14NH3) and phosphine (31PH3) are calculated as a function of temperature by explicit summation of 153 million (for PH3) and 7.5 million (for NH3) theoretical rotation-vibrational energy levels. High accuracy estimates are obtained for the specific heat capacity, Cp, the Gibbs enthalpy function, gef, the Helmholtz function, hcf, and the entropy, S, of gas phase molecules as a function of temperature. In order to reduce the computational costs associated with the high rotational excitations, only the A-symmetry energy levels are used above a certain threshold of the total angular momentum number J. With this approach levels are summed up to dissociation energy for values of Jmax=45 and 100 for ammonia (Emax=41 051 cm-1) and phosphine (Emax=28 839.7 cm-1), respectively. Estimates of the partition function are converged for all temperatures considered for phosphine and below 3000 K for ammonia. All other thermodynamic properties are converged to at least 2000 K for ammonia and fully converged for phosphine.

Sousa-Silva, Clara; Hesketh, Nicholas; Yurchenko, Sergei N.; Hill, Christian; Tennyson, Jonathan

2014-07-01

100

Factors Affecting Energy Barriers for Pyramidal Inversion in Amines and Phosphines: A Computational Chemistry Lab Exercise  

ERIC Educational Resources Information Center

An undergraduate exercise in computational chemistry that investigates the energy barrier for pyramidal inversion of amines and phosphines is presented. Semiempirical calculations (PM3) of the ground-state and transition-state energies for NR[superscript 1]R[superscript 2]R[superscript 3] and PR[superscript 1]R[superscript 2]R[superscript 3] allow…

Montgomery, Craig D.

2013-01-01

101

Hydroxymethyl phosphine compounds for use as diagnostic and therapeutic pharmaceuticals and method of making same  

DOEpatents

A compound and method of making a compound for use as a diagnostic or therapeutic pharmaceutical comprises at least one functionalized hydroxyalkyl phosphine donor group and one or more sulfur or nitrogen donor and a metal combined with the ligand. 21 figs.

Katti, K.V.; Karra, S.R.; Berning, D.E.; Smith, C.J.; Volkert, W.A.; Ketring, A.R.

1999-01-05

102

Palladium/sulfoxide-phosphine-catalyzed highly enantioselective allylic etherification and amination.  

PubMed

The Pd/sulfoxide-phosphine-catalyzed highly enantioselective allylic etherification and amination with a wide range of O- and N-nucleophiles have been developed (up to 97% yield, 98.5% ee). The products can also be conveniently transformed into biologically active chiral heterocycles. PMID:25012792

Feng, Bin; Cheng, Hong-Gang; Chen, Jia-Rong; Deng, Qiao-Hui; Lu, Liang-Qiu; Xiao, Wen-Jing

2014-07-24

103

Lithium cation enhances anion binding in a tripodal phosphine oxide-based ditopic receptor†  

PubMed Central

A tripodal ditopic receptor presents H-bond donors and a phosphine oxide to potential guests. In the idealized binding conformation, an endohedral P?O functionality provides enhanced halide binding in the presence of lithium with the greatest ??G° observed for bromide, while minimal changes in Ka are observed in the presence of sodium.

Gavette, Jesse V.; Lara, Juven; Berryman, Orion B.; Zakharov, Lev N.; Haley, Michael M.; Johnson, Darren W.

2012-01-01

104

Catalytic Oxidation of Phosphines by Transition Metal-Activated Carbon Dioxide.  

National Technical Information Service (NTIS)

The complexes (Ph3P) 3RhCl and (cyclooctene) 2RhCl 2 have been found to catalyze the oxidation of phosphines by carbon dioxide in refluxing decalin. The rate of oxidation increases in the order PPh3 less than PBuPh2 less than PEt3. (Author)

K. M. Nicholas

1979-01-01

105

Observations of the J = 10 Manifold of the Pure Rotational Band of Phosphine on Saturn.  

National Technical Information Service (NTIS)

Saturn was observed in the vicinity of the J = 10 manifold of the pure rotational band of phosphine on 1984 July 10 and 12 from NASA's Kuiper Airborne Observatory with the facility far-infrared cooled grating spectrometer. On each night observations of th...

M. R. Haas E. F. Erickson D. Goorvitch D. D. Mckibbin D. M. Rank

1986-01-01

106

New chiral phosphine-phosphite ligands in the enantioselective palladium-catalyzed allylic alkylation  

PubMed

A series of chiral phosphine-phosphite ligands 1-6 have been synthesized and used in the enantioselective palladium-catalyzed reaction of rac-1,3-diphenyl-2-propenyl acetate with dimethyl malonate as nucleophile. Ligands 1a, 2, 3, 5a, 6a, and 6b have been synthesized starting from racemic tert-butylphenylphosphinoborane. The use of dynamically resolved Li phosphide (-)-sparteine provided the optically pure ligands. Crystals of the allylpalladium (6a) complex were obtained, suitable for X-ray crystal structure determination. The X-ray crystal structure of the allylpalladium (6a) complex revealed a longer palladium-carbon bond distance trans to the phosphine moiety indicating that the attack of the nucleophile takes place at the carbon trans to the phosphine moiety. This was confirmed by the fact that the phosphine moiety did not affect the enantioselectivity directly. Under mild reaction conditions, enantioselectivities up to 83% were obtained (25 degrees C) with ligand 1e. Systematic variation of the ligand bridge and the phosphite moiety showed that the configuration of the product is controlled by the atropisomerism of the biphenyl substituent at the phosphite moiety. The conformation of the biphenyl group, in turn, is controlled by the substituent at the chiral carbon in the bridge. Ligands with large bite angles yielded higher enantioselectivities. PMID:10956456

Deerenberg; Schrekker; van Strijdonck GP; Kamer; van Leeuwen PW; Fraanje; Goubitz

2000-08-11

107

Total Synthesis of (?)-Hirsutine: Application of Phosphine-Catalyzed Imine-Allene [4 + 2] Annulation  

PubMed Central

The total synthesis of the indole alkaloid hirsutine has been achieved, with a key step being the application of our phosphine-catalyzed [4 + 2] annulation of an imine with ethyl ?-methylallenoate. From commercially available indole-2-carboxaldehyde, the target was synthesized in 14 steps and 6.7% overall yield.

Villa, Reymundo A.; Xu, Qihai; Kwon, Ohyun

2012-01-01

108

Hydroxyalkyl phosphine gold complexes for use as diagnostic and therapeutic pharmaceuticals and method of making same  

DOEpatents

A complex and method for making a diagnostic or therapeutic pharmaceutical includes a ligand comprising at least one hydroxyalkyl phosphine donor group bound to a gold atom to form a gold-ligand complex that is stable in aqueous solutions containing oxygen, serum and other body fluids. 20 figs.

Katti, K.V.; Berning, D.E.; Volkert, W.A.; Ketring, A.R.

1998-12-01

109

Hydroxyalkyl phosphine gold complexes for use as diagnostic and therapeutic pharmaceuticals and method of making same  

DOEpatents

A complex and method for making same for use as a diagnostic or therapeutic pharmaceutical includes a ligand comprising at least one hydroxyalkyl phosphine donor group bound to a gold atom to form a gold-ligand complex that is stable in aqueous solutions containing oxygen, serum and other body fluids.

Katti, Kattesh V. (Columbia, MO); Berning, Douglas E. (Columbia, MO); Volkert, Wynn A. (Columbia, MO); Ketring, Alan R. (Columbia, MO)

1998-01-01

110

Resolution of Chiral Phosphate, Phosphonate, and Phosphinate Esters by an Enantioselective Enzyme Library  

Microsoft Academic Search

An array of 16 enantiomeric pairs of chiral phosphate, phosphonate, and phosphinate esters was used to establish the breadth of the stereoselective discrimination inherent within the bacterial phosphotriesterase and 15 mutant enzymes. For each substrate, the leaving group was 4-hydroxyac- etophenone while the other two groups attached to the phosphorus core consisted of an asymmetric mixture of methyl, methoxy, ethyl,

Charity Nowlan; Yingchun Li; Johannes C. Hermann; Timothy Evans; Joseph Carpenter; Eman Ghanem; Brian K. Shoichet; Frank M. Raushel

2006-01-01

111

Total synthesis of (±)-hirsutine: application of phosphine-catalyzed imine-allene [4 + 2] annulation.  

PubMed

The total synthesis of the indole alkaloid hirsutine has been achieved, with a key step being the application of our phosphine-catalyzed [4 + 2] annulation of an imine with ethyl ?-methylallenoate. From commercially available indole-2-carboxaldehyde, the target was synthesized in 14 steps and 6.7% overall yield. PMID:22920858

Villa, Reymundo A; Xu, Qihai; Kwon, Ohyun

2012-09-01

112

Simple Analysis Method to Measure Phosphine Residue in Grains, Herbs, and Spices Using Headspace Gas Chromatography  

Microsoft Academic Search

Trials were conducted to determine whether an analysis method for measuring phosphine residue using a headspace autosampler, which provides rapid analysis and easier handling, is equally applicable to herbs and spices and other kinds of grains as it is to wheat and small beans. For measur- ing residue levels, the optimal equilibrium time, best sample amount per vial, and impact

Takashi MISUMI; Hisashi KITAMURA; Tetsuo OOGITA

113

Phosphine-catalyzed reductions of alkyl silyl peroxides by titanium hydride reducing agents: development of the method and mechanistic investigations.  

PubMed

A method that allows for the reduction of protected hydroperoxides by employing catalytic amounts of phosphine is presented. The combination of a titanium(IV) alkoxide and a siloxane allowed for the chemoselective reduction of phosphine oxides in the presence of alkyl silyl peroxides. Subsequent reduction of the peroxide moiety by phosphine provided the corresponding silylated alcohols in useful yields. Mechanistic experiments, including crossover experiments, support a mechanism in which the peroxide group was reduced and the silyl group was transferred in a concerted step. Labeling studies with (17)O-labeled peroxides demonstrate that the oxygen atom adjacent to the silicon atom is removed from the silyl peroxide. PMID:20604518

Harris, Jason R; Haynes, M Taylor; Thomas, Andrew M; Woerpel, K A

2010-08-01

114

Cobalt (iron) thiolato complexes containing the Co-ligand phosphine and reaction products of the structural fragment M L 2 L ? ( L = 1,2-bidentate thiolate, L ?= tertiary phosphine)  

Microsoft Academic Search

Mono-, di-, tri-, and tetra-nuclear cobalt (iron) complexes containing co-ligands phosphine and thiolate are presented according to the classification by combination of different dentates of the two ligands. Emphasis is being put on the triand tetranuclear cluster complexes of monodentate phosphines and 1,2-bidentate thiolates. These complexes are considered to be constructed based on the general structural fragment (or building block)

Bei-Sheng Kang; Zhong-Ning Chen; Zhong-Yuan Zhou; Han-Qin Liu; Han-Rong Gao; Bo-Mu Wu; Thomas C. W. Mak; Yuan-Ba Cai; Yong-Jin Xu; Zhi-Tao Xu

1996-01-01

115

Mutagenic Potential of: 4-Nitrophenyl Diphenyl Phosphinate Using the Drosophila melanogaster Sex-Linked Recessive Lethal Test.  

National Technical Information Service (NTIS)

The compound 4-nitrophenyl diphenyl phosphinate (TA016) is being considered as a prophylatic agent in anticholinesterase poisoning. It was tested for mutagenic activity using Drosophila melanogaster Sex-linked Recessive Lethal Assay. After 72-hour feeding...

N. R. Powers P. P. Waring

1983-01-01

116

Stereoselective synthesis of o-bromo (or iodo)aryl P-chirogenic phosphines based on aryne chemistry.  

PubMed

The efficient synthesis of chiral or achiral tertiary phosphines bearing an o-bromo (or iodo)aryl substituent is described. The key step of this synthesis is based on the reaction of a secondary phosphine borane with the 1,2-dibromo (or diiodo)arene, owing to the formation in situ of an aryne species in the presence of n-butyllithium. When P-chirogenic secondary phosphine boranes were used, the corresponding o-halogeno-arylphosphine boranes were obtained without racemization in moderate to good yields and with ee up to 99%. The stereochemistry of the reaction, with complete retention of the configuration at the P atom, has been established by X-ray structures of P-chirogenic o-halogenophenyl phosphine borane complexes. The decomplexation of the borane was easily achieved without racemization using DABCO to obtain the free o-halogeno-arylphosphines in high yields. PMID:22708733

Bayardon, Jérôme; Laureano, Hugo; Diemer, Vincent; Dutartre, Mathieu; Das, Utpal; Rousselin, Yoann; Henry, Jean-Christophe; Colobert, Françoise; Leroux, Frédéric R; Jugé, Sylvain

2012-07-01

117

Transition-Metal Fluoro Compounds Containing Carbonyl, Phosphine, Arsine and Stibine Ligands. (Reannouncement with New Availability Information).  

National Technical Information Service (NTIS)

This review describes the considerable variety of transition-metal fluoro compounds containing carbonyl, phosphine, arsine, and stibine ligands reported in the literature. Included are a number of stable low-valent organometallic fluorides, a class of com...

N. M. Doherty N. W. Hoffman

1991-01-01

118

Synthesis of new hydrophilic phosphines by addition of diphenylphosphine on activated alkenes: characterization of their rhodium complexes  

Microsoft Academic Search

The regioselective addition of diphenylphosphine on conjugated olefins leads to new hydrophilic phosphines. Ligands with various functional groups (carboxylic, sulfonate, trimethylammonium and hydroxy) and their neutral and cationic rhodium complexes have been prepared and characterized.

L Lavenot; M. H Bortoletto; A Roucoux; C Larpent; H Patin

1996-01-01

119

Regioselective Reduction of Quinolines Catalyzed by Rhodium and Iridium Complexes with mono-, di-, and tri-dentated Phosphine Ligands  

Microsoft Academic Search

The systems prepared in situ by addition of the corresponding equivalents of the respective phosphine (mono-, di- and tri-dentated), called M2Cl2(COE)4\\/n phosphine (M = Rh, Ir; and COE = cyclooctene), are efficient and regioselective precatalysts for the hydrogenation of quinoline,\\u000a isoquinoline, 5,6- and 7,8-benzoquinoline and acridine. The Rh systems were more active than the corresponding Ir ones, being\\u000a the systems

Merlín Rosales; Regina Vallejo; Juan José Soto; Gustavo Chacón; Ángel González; Beatriz González

2006-01-01

120

Complexation of diphenyl(phenylacetenyl)phosphine to rhodium(III) tetraphenyl porphyrins: synthesis and structural, spectroscopic, and thermodynamic studies.  

PubMed

The coordination of diphenyl(phenylacetenyl)phosphine (DPAP, 1) to (X)Rh(III)TPP (X = I (2) or Me (3); TPP = tetraphenyl porphyrin) was studied in solution and in the solid state. The iodide is readily displaced by the phosphine, leading to the bis-phosphine complex [(DPAP)(2)Rh(TPP)](I) (4). The methylide on rhodium in 3 is not displaced, leading selectively to the mono-phosphine complex (DPAP)(Me)Rh(TPP) (5). The first and second association constants, as determined by isothermal titration calorimetry and UV-vis titrations, are in the range 10(4)-10(7) M(-1) (in CH(2)Cl(2)). Using LDI-TOF mass spectrometry, the mono-phosphine complexes can be detected but not the bis-phosphine complexes. The electronic spectrum of 4 is similar to those previously reported with other tertiary phosphine ligands, whereas (DPAP)(I)Rh(TPP) (6) displays a low energy B-band absorption and a high energy Q-band absorption. In contrast to earlier reports, displacement of the methylide on rhodium in 5 could not be observed at any concentration, and the electronic spectra of 4 and 5 are almost identical. Isothermal titration calorimetry experiments showed that all binding events are exothermic, and all are enthalpy driven. The largest values of DeltaG degrees are found for 6. The thermodynamic and UV-vis data reveal that the methylide and the phosphine ligand have an almost identical electronic trans-influence on the sixth ligand. PMID:12716205

Stulz, Eugen; Scott, Sonya M; Bond, Andrew D; Otto, Sijbren; Sanders, Jeremy K M

2003-05-01

121

Laboratory Measurements of the Microwave Opacity of Phosphine: Opacity Formalism and Application to the Atmospheres of the Outer Planets  

Microsoft Academic Search

Preliminary room-temperature measurements of the microwave opacity of phosphine (Hoffman and Steffes 1999). Icarus140, 235–238, suggested that phosphine (PH3) may contribute significantly to the microwave emission spectrum of Neptune, and to the centimeter-wavelength opacity measured by the Voyager 2 spacecraft at Neptune and Saturn. As a result, new laboratory measurements of the microwave opacity of PH3 in an H2\\/He atmosphere

James P. Hoffman; Paul G. Steffes; David R. DeBoer

2001-01-01

122

Continuous real-time monitoring of phosphine concentrations in air using electrochemical detectors interfaced by radio telemetry.  

PubMed

This work involves the novel use of a radio telemetry-based system that continuously monitors phosphine using two different types of electrochemical detectors (ECD/RT). The ECD/RT units were used to monitor phosphine inside and at varying distances from large tobacco storage warehouses. A master controller unit transferred the data to a personal computer that received and displayed the data. Supervisory control and data acquisition software assimilated the data from each ECD/RT unit, displayed and updated it as new transmissions were received, and stored the data in secure databases. Phosphine concentrations outside five warehouses simultaneously under fumigation and at the facility boundaries were <0.3 parts per million (ppm). Phosphine levels ranged from 0 to 580 ppm inside sealed warehouses. A comparison was made between the data collected at an ECD/RT unit approximately 4 m downwind of a sealed warehouse and a colorimetric tube at the same location. The final phosphine concentration from the colorimetric method was 0.05 ppm and the average over the 20-minute collection period for the ECD/RT was 0.13 ppm. This system allows for continuous, remote monitoring around warehouses under fumigation and superior time resolution allowing timely response to fugitive emissions of phosphine. PMID:12026991

Thorn, Tommy G; Chodyniecki, Edward M; Ingold, Kenneth W; Long, Gerald A; Miller, Charles D; Robinson, Edward A; Cowan, F Scott; Thomas, Robert L

2002-05-01

123

Phosphines are ribonucleotide reductase reductants that act via C-terminal cysteines similar to thioredoxins and glutaredoxins  

PubMed Central

Ribonucleotide reductases (RNRs) catalyze the formation of 2?-deoxyribonucleotides. Each polypeptide of the large subunit of eukaryotic RNRs contains two redox-active cysteine pairs, one in the active site and the other at the C-terminus. In each catalytic cycle, the active-site disulfide is reduced by the C-terminal cysteine pair, which in turn is reduced by thioredoxins or glutaredoxins. Dithiols such as DTT are used in RNR studies instead of the thioredoxin or glutaredoxin systems. DTT can directly reduce the disulfide in the active site and does not require the C-terminal cysteines for RNR activity. Here we demonstrate that the phosphines tris(2-carboxyethyl)phosphine (TCEP) and tris(3-hydroxypropyl)phosphine (THP) are efficient non-thiol RNR reductants, but in contrast to the dithiols DTT, bis(2-mercaptoethyl)sulfone (BMS), and (S)-(1,4-dithiobutyl)-2-amine (DTBA) they act specifically via the C-terminal disulfide in a manner similar to thioredoxin and glutaredoxin. The simultaneous use of phosphines and dithiols results in ~3-fold higher activity compared to what is achieved when either type of reductant is used alone. This surprising effect can be explained by the concerted action of dithiols on the active-site cysteines and phosphines on the C-terminal cysteines. As non-thiol and non-protein reductants, phosphines can be used to differentiate between the redox-active cysteine pairs in RNRs.

Domkin, Vladimir; Chabes, Andrei

2014-01-01

124

Recycle and recovery of rhodium complexes with water-soluble and amphiphilic phosphines in ionic liquids for hydroformylation of 1-hexene  

Microsoft Academic Search

A biphasic catalysis system composed of ionic liquid and rhodium complexes with water-soluble or amphiphilic phosphine ligands\\u000a bearing water-soluble groups of sodium sulfonate have been employed for hydroformylation of 1-hexene. The experimental results\\u000a show that the activity is almost independent of the hydrotropicity of the phosphine ligands in BMIBF4. In this system, the extraction of phosphine species by the organics

Qingrong Peng; Changxi Deng; Yong Yang; Maohua Dai; Youzhu Yuan

2007-01-01

125

Different coordination behavior of a catechol phosphine and its sulfide: Formation of an unprecedented dinuclear rhodium complex with a non-coordinated P S unit  

Microsoft Academic Search

Sulfurization of 3-[(diphenylphosphinyl)methyl]benzene-1,2-diol 1 produced phosphine sulfide 3. Both ligands reacted easily to form gold(I) and rhodium(I) complexes which were characterized by analytical and spectroscopic data, and single-crystal X-ray diffraction studies. Whereas the phosphine prefers to form complexes with a metal-to-ligand ratio of 1:2 with both metals, the phosphine sulfide exhibits a reduced donor power and yields only a 1:1

Gernot Bauer; Cornelia Englert; Martin Nieger; Dietrich Gudat

2011-01-01

126

Rapid geometrical equilibrium of palladium(II) complexes with tris[2-(diphenylphosphino)ethyl]phosphine disulfide and diselenide and their catalytic activity for Suzuki coupling reaction  

Microsoft Academic Search

Palladium(II) complexes with a tetradentate pseudo-tripodal ligand having two phosphino groups and two phosphine sulfide or selenide groups, pp3X2 (pp3=tris[2-(diphenylphosphino)ethyl]phosphine, X=S (1) or Se (2)), were prepared from [PdCl(pp3)]Cl. Both of these phosphine chalcogenide complexes 1 and 2 showed rapid equilibrium between the five-coordinate [PdCl(pp3X2)]Cl with two bound phosphine chalcogenide groups and four-coordinate [PdCl2(pp3X2)] with two dissociated pendant ones in

Sen-ichi Aizawa; Takashi Hase; Tsuyoshi Wada

2007-01-01

127

Rate constant for the reaction of atomic oxygen with phosphine at 298 K  

NASA Technical Reports Server (NTRS)

The rate constant for the reaction of atomic oxygen with phosphine has been measured at 298 K using flash photolysis combined with time-resolved detection of O(3P) via resonance fluorescence. Atomic oxygen was produced by flash photolysis of N2O or NO highly diluted in argon. The results were shown to be independent of (PH3), (O), total pressure and the source of O(3P). The mean value of all the experiments is k1 = (3.6 + or -0.8) x 10 to the -11th cu cm/s (1 sigma). Two previous measurements of k1 differed by more than an order of magnitude, and the results support the higher value obtained in a discharge flow-mass spectrometry study. A comparison with rate data for other atomic and free radical reactions with phosphine is presented, and the role of these reactions in the aeronomy or photochemistry of Jupiter and Saturn is briefly considered.

Stief, L. J.; Payne, W. A.; Nava, D. F.

1987-01-01

128

Synthesis and proton NMR studies of the electronic structure of ferric phosphine porphyrin complexes  

SciTech Connect

The preparation and spectral properties of low-spin ferric phosphine complexes of a series of synthetic and natural porphyrins have been reported. The proton NMR spectra of Fe(TPP)(PMe/sub 3/)/sub 2/ClO/sub 4/ and Fe(TPP)(PMe/sub 3/)(1-Melm)ClO/sub 4/ have been analyzed. The axial ligand hyperfine shifts have been separated into their dipolar and contact contributions by using both the dominant dipolar shifts for certain porphyrin positions and the magnetic anisotropy data derived from low-temperature ESR spectra. The contact shifts are shown to arise primarily from iron ..-->.. phosphine ..pi..* charge transfer. The trimethylphosphine H peak is shown to shift characteristically upfield on going from (Fe(TPP)PMe/sub 32/)/sup +/ to (Fe(TPP)(PMe/sub 3/)(1-MeIm))/sup +/, confirming that this resonance may serve as a new probe for hemoproteins. 25 references, 2 figures, 3 tables.

Simonneaux, G.; Sodano, P.

1988-11-02

129

Highly efficient blue electrophosphorescent polymers with fluorinated poly(arylene ether phosphine oxide) as Backbone.  

PubMed

In view of the tolerance of F atoms in FIrpic to the nucleophilic aromatic substitution polymerization, an activated fluorinated poly(arylene ether phosphine oxide) backbone is used to construct novel blue electrophosphorescent polymers containing FIrpic as the blue emitter, because they can be synthesized under a milder temperature of 120 °C. Compared with the counterparts prepared at high temperature (165 °C), unexpected bathochromic shift is successfully avoided, and a state-of-art luminous efficiency as high as 19.4 cd A(-1) is achieved. The efficiency is comparable to the corresponding physical blend system, which indicates that the fluorinated poly(arylene ether phosphine oxide) has the potential to be used as the platform for the development of high-performance all-phosphorescent white polymer based on single polymer system. PMID:22950598

Shao, Shiyang; Ding, Junqiao; Wang, Lixiang; Jing, Xiabin; Wang, Fosong

2012-09-19

130

Low-temperature sup 31 P NMR studies of metal phosphine clusters  

SciTech Connect

(Au(PPh{sub 3})(AuPPh{sub 3}){sub 7}){sup 2+}, (Pt(H)(PPh{sub 3})(AuPPh{sub 3}){sub 8}){sup 3+} show sharp {sup 31}P NMR resonances in solutions at room temperature although from the solid-state structure different phosphine sites are expected. This is due to fluxionality, the chemical exchange of different phosphorus sites. This process can be slowed by lowering the temperature, and in this slow-exchange regime the different phosphine sites can be assigned by means of {sup 31}P homonuclear shift correlated spectroscopy methods. The tensor surface harmonics model, which is used for the description of the bonding in this type of clusters, offers a rationale for the trends in the observed magnitude of the coupling constants. Deviation of this model is observed for the toroidal clusters, in which the peripheral interactions are shown to be stronger than in the spheroidal clusters. 21 refs., 10 figs., 1 tab.

Kanters, R.P.F.; Schlebos, P.P.J.; Bour, J.; Steggerda, J.J.; Maas, W.E.J.R.; Janssen, R. (Univ. of Nijmegen (Netherlands))

1991-04-01

131

Synthesis and Lanthanide Coordination Chemistry of Phosphine Oxide Decorated Dibenzothiophene and Dibenzothiophene Sulfone Platforms  

SciTech Connect

Syntheses for new ligands based upon dibenzothiophene and dibenzothiophene sulfone platforms, decorated with phosphine oxide and methylphosphine oxide donor groups, are described. Coordination chem. of 4, 6- bis(diphenylphosphinoylmethyl) dibenzothiophene (8) , 4, 6- bis(diphenylphosphinoylmethyl) dibenzothiophene- 5, 5- dioxide (9) and 4, 6- bis(diphenylphosphinoyl) dibenzothiophene- 5, 5- dioxide (10) with lanthanide nitrates, Ln(NO3) 3 (H2O) n is outlined, and crystal structure detns. reveal a range of chelation interactions on Ln(III) ions. The HNO3 dependence of the solvent extn. performance of 9 and 10 in 1, 2- dichloroethane for Eu(III) and Am(III) is described and compared against the extn. behavior of related dibenzofuran ligands (2, 3; R = Ph) and n- octyl(phenyl) - N, N- diisobutylcarbamoylmethyl phosphine oxide (4) measured under identical conditions.

Rosario-Amorin, Daniel [University of New Mexico, Albuquerque] [University of New Mexico, Albuquerque; Ouizem, Sabrina [University of New Mexico, Albuquerque] [University of New Mexico, Albuquerque; Dickie, D. A. [University of New Mexico, Albuquerque] [University of New Mexico, Albuquerque; Paine, Robert T. [University of New Mexico, Albuquerque] [University of New Mexico, Albuquerque; Cramer, Roger E. [University of Hawaii] [University of Hawaii; Hay, Benjamin [ORNL] [ORNL; Podair, Julien [ORNL] [ORNL; Delmau, Laetitia Helene [ORNL] [ORNL

2014-01-01

132

Diphosphine is an intermediate in the photolysis of phosphine to phosphorus and hydrogen. [Jupiter atmospheric chemistry  

NASA Technical Reports Server (NTRS)

The photolysis of phosphine to red phosphorus (P4) and hydrogen is investigated in light of the potential significance of the reaction in the atmospheric chemistry of Jupiter. It is reported that the photolysis of PH3 at room temperature by a 206.2-nm light source gave rise to a product identified by its UV and IR spectra and gas chromatographic retention time as P2H4, the yield of which is found to increase to a maximum and then decrease to 20% of the maximum value with illumination time. A mechanism for phosphine photolysis including diphosphine formation as an intermediate step is proposed, and it is concluded that P2H4 is a likely constituent of the atmospheres of the Jovian planets.

Ferris, J. P.; Benson, R.

1980-01-01

133

Copper Loaded on Sol-Gel-Derived Alumina Adsorbents for Phosphine Removal  

Microsoft Academic Search

The hydride gas of phosphine (PH3) is commonly used for semiconductor and optoelectronic industries. The local scrubbers must immediately abate it because of its high toxicity. In this study, copper (Cu) loaded on the sol-gel-derived ?-alumina (Al2O3) adsorbents are prepared and tested to investigate the possibility of PH3 removal and sorbent regeneration. Test results showed that during the breakthrough time

Jung-Nan Hsu; Hsunling Bai; Shou-Nan Li; Chuen-Jinn Tsai; Jyh-Feng Hwang; Wang Chen; Elisabeth Gilmore; Peter Adams; Lester Lave; Huabo Duan; Weifeng Jia; Jinhui Li; Violeta Mugica; Sara Hernandez; Miguel Torres; Rocio García; Antton Melendez; Estibaliz García; Pedro Carnicer; Egoitz Pena; Miren Larrion; Juan Legarreta; Cristina Gutierrez-Canas; Parikhit Sinha; William Schew; Aniket Sawant; Kyle Kolwaite; Sarah Strode; Stephanie Weber; Jill Engel-Cox; Raymond Hoff; Ana Prados; Hai Zhang; Valerie Garcia; Kristen Foley; Edith Gego; David Holland; S. Rao; Sundar Christopher; Pawan Gupta; Chengwen Wang; Yujue Wang; Yanqi Zhang; Qi Zhao; Ran Wang; Christian Murray; Frederick Lipfert

2010-01-01

134

Extraction and separation of rare earth metals using microcapsules containing bis(2-ethylhexyl)phosphinic acid  

Microsoft Academic Search

The separation of rare earth metals using microcapsules (MC) consisting styrene (St)–divinylbenzene (DVB) copolymer and containing bis(2-ethylhexyl)phosphinic acid (PIA-226) has been investigated. Microcapsules containing PIA-226 can be prepared by adding PIA-226 to the dispersed phase during the preparation process. The extraction of rare earth metals with the microcapsules progresses via the same scheme, as proposed in the conventional liquid–liquid extraction

Syouhei Nishihama; Nobuya Sakaguchi; Takayuki Hirai; Isao Komasawa

2002-01-01

135

The reaction of secondary phosphines and di-1-adamantylphosphine oxide with trifluoroacetic anhydride and hexafluoroacetone  

Microsoft Academic Search

While the secondary phosphines (1-Ad)2PH (1) (l-Ad = adamantyl) and Trt(Ph)PH (2) (Trt = triphenylmethyl) reacted readily with trifluoroacetic anhydride (TFAA) to give the trifluoroacetylphosphines 7 and 8. (1-Ad)2P(:O)H (6) could not be converted into the corresponding trifluoroacetylphosphine oxide 10 by treatment with TFAA. Compound 10 was observed by 19F and 31P NMR spectroscopy in the reaction of (1-Ad)2PC(:O)CF3(7) with

Jens R. Goerlich; Volker Plack; Reinhard Schmutzler

1996-01-01

136

Hydroformylation of alkenes employing rhodium(i) complexes and a phosphine oxide ligand.  

PubMed

Following the facile synthesis of a novel phosphine oxide compound, (diphenylphosphinoyl)phenylmethanol (1), this compound was employed as a ligand in the rhodium-catalyzed hydroformylation of alkenes, with good conversions and regioselectivities. This ligand was partially resolved using an enzyme, and enantioselective hydroformylation was carried out with the addition of a rhodium(I) complex. The rhodium(I) complex containing ligand 1 was not isolated, although it was subjected to low-temperature NMR studies. PMID:12182665

Clark, Helen J; Wang, Ruiping; Alper, Howard

2002-08-23

137

Phosphine?carbon disulfide adducts, S 2CPR 3: versatile ligands in coordination chemistry  

Microsoft Academic Search

Phosphine?carbon disulfide adducts, S2CPR3, are very versatile ligands that exhibit a variety of coordination modes to transition metal centers. These compounds are able to formally donate from 2 to 8e? to a metal (or metals). A resume of the synthetic methodology to prepare them, a rationalization of the structural diversity found in this type of complexes, and their main spectroscopic

Agustin Galindo; Daniel Miguel; Julio Perez

1999-01-01

138

Flow Heck reactions using extremely low loadings of phosphine-free palladium acetate.  

PubMed

High-yielding Heck reactions are demonstrated using 0.05 mol % Pd(OAc)2 without phosphine ligands. These reactions are run in a mesoscale flow reactor which allows precise control of reaction times and temperatures. Profiling yield and selectivity versus Pd loading shows 500 ppm to be optimal for aryl iodides; higher loadings favor side reactions caused by Pd(II) species. Aryl halides are examined via concise Design of Experiment to expand the scope and optimize conditions. PMID:23937686

Cyr, Patrick; Deng, Stella T; Hawkins, Joel M; Price, Kristin E

2013-09-01

139

The Lamb-dip spectrum of phosphine: The nuclear hyperfine structure due to hydrogen and phosphorus  

Microsoft Academic Search

For the first time, the hyperfine structure of the rotational J=1?0 (K=0) and J=2?1 (K=0, 1) transitions of phosphine has been resolved by using microwave spectroscopy. To this purpose, the Lamb-dip technique has been employed. In addition, the J=3?2 (K=0, 1, 2) transition has been recorded at Doppler resolution. The present investigation allowed us to provide accurate values for most

Gabriele Cazzoli; Cristina Puzzarini

2006-01-01

140

Di-?-thio-cyanato-bis-[bis-(tri-p-tolyl-phosphine)silver(I)] 0.35-hydrate  

PubMed Central

In the binuclear centrosymmetric title compound, [Ag2(NCS)2(C21H21P)4]·0.35H2O, a pseudo-polymorph of [Ag2(NCS)2(C21H21P)4]·2CH3CN, the Ag atom is coordinated by two phosphine ligands and two bridging thio­cyanate ligands in a distorted tetra­hedral configuration. The crystal structure exhibits inter­molecular C—H?? inter­actions.

Khumalo, Nozipho M.; Meijboom, Reinout; Muller, Alfred; Omondi, Bernard

2010-01-01

141

Fire retardant systems in poly(methyl methacrylate): Interactions between metal oxide nanoparticles and phosphinates  

Microsoft Academic Search

In the course of our investigations on halogen-free fire-retardant solutions for PMMA, the influence of oxide nanoparticles (TiO2, Al2O3) on the thermal stability and fire behaviour of PMMA blended with phosphinate additives (Exolit OP930 and OP1311) has been studied by thermogravimetric analysis and cone calorimetry. For each mixture, the residues obtained after combustion were examined and characterized by SEM, X-ray

A. Laachachi; M. Cochez; E. Leroy; M. Ferriol; J. M. Lopez-Cuesta

2007-01-01

142

Formation of an iron phosphine-borane complex by formal insertion of BH? into the Fe-P bond.  

PubMed

A unique hydrido phosphine-borane iron(II) complex [(dppa)(Ph?P-N-P(BH?)Ph?)Fe(H)] (1) was obtained by the reaction of iron(II) chloride and two equivalents of bis(diphenylphosphino)amine (dppa) with an excess of sodium borohydride in acetonitrile-ethanol mixtures. Detailed investigations of the reaction revealed that a mixture of cis- and trans-[(dppa)?Fe(NCMe)?]²? is formed prior to the reduction by sodium borohydride. Depending on the solvent, different products were obtained by the reduction: in acetonitrile-ethanol mixtures the hydrido phosphine-borane complex 1 is formed by formal insertion of BH?, while the reduction in pure acetonitrile results in the formation of the cationic complex trans-[(dppa)?Fe(H)(NCMe)](BH?) (4). Complex 4 is remarkably stable in ethanol and does not undergo phosphine-borane formation, even in the presence of excess sodium borohydride. This observation suggests that the phosphine-borane complex is generated by the reaction with the first equivalent of sodium borohydride with the participation of ethanol, followed by deprotonation or dihydrogen elimination. Experiments with similar diphosphine ligands, such as bis(diphenylphosphino)methane, did not yield a phosphine-borane complex, indicating the crucial role of the amine group in the observed reactivity. PMID:23811820

Frank, Nicolas; Hanau, Katharina; Flosdorf, Kimon; Langer, Robert

2013-08-21

143

Low temperature phosphine fumigation for postharvest control of western flower thrips (Thysanoptera: Thripidae) on lettuce, broccoli, asparagus, and strawberry.  

PubMed

U.S. exported lettuce, broccoli, asparagus, and strawberries often harbor western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), a quarantined pest in Taiwan, and therefore require quarantine treatment. Fumigation with diluted pure phosphine at a low temperature of 2 degrees C was studied to control western flower thrips and to determine effects on the quality of the treated products. Total thrips control was achieved in > or = 18-h fumigation treatments with > or = 250 ppm phosphine. One day fumigation treatment with 1,000 ppm phosphine was tested on lettuce and broccoli. One-day fumigation treatments with 500 ppm and 1,000 ppm phosphine were tested on asparagus and strawberry. Visual quality of lettuce, broccoli, and asparagus was evaluated after 2-wk posttreatment storage. Strawberry quality was evaluated immediately after fumigation and after 1-wk posttreatment storage. For all the products, there were no significant differences between the treatments and the controls in postharvest quality, and there were no injuries caused by the fumigation treatments. Therefore, phosphine fumigation at low temperature was promising for postharvest control of western flower thrips on lettuce, broccoli, asparagus, and strawberry. PMID:19133457

Liu, Yong-Biao

2008-12-01

144

Effects of phosphine and methyl bromide fumigation on the volatile flavor profile and sensory quality of dry cured ham.  

PubMed

In separate experiments, randomized complete block designs with three replications were utilized to evaluate the effects of phosphine (PH(3)) (0, 200 and 1000ppm for 48h) and methyl bromide (MB) (0, 4, 8, 16, and 32mg/L for 48h) fumigation concentration on the volatile flavor compound concentrations in dry cured ham. Minimal differences existed (P>0.05) in the presence and concentration of aroma active compounds in both PH(3) and MB fumigated hams but sulfur and oxidation compounds were more prevalent (P<0.05) in the fumigated treatments when compared to the control. As phosphine fumigation concentration increased, the residual concentration of phosphine also increased in the hams (P<0.05), but all samples contained levels that are lower than the legal limit of phosphine allowed in stored food products (0.01ppm) in the United States. A triangle test (n=56) indicated that consumers could not discriminate (P>0.75) between the control hams and those that were fumigated with PH(3). Minimal aroma/flavor differences existed among MB, PH3 and control hams, and dry cured ham that was fumigated with PH(3) was safe for consumption based on residual phosphine concentrations in the meat tissue. PMID:20554396

Sekhon, R K; Schilling, M W; Phillips, T W; Aikins, M J; Hasan, M M; Corzo, A; Mikel, W B

2010-10-01

145

Reactions of Elemental Phosphorus and Phosphine with Electrophiles in Superbasic Systems: XV. Phosphorylation of Allyl Halides with Elemental Phosphorus  

Microsoft Academic Search

Elemental phosphorus (red or white) reacts with allyl chloride and allyl bromide in a two-phase system aqueous KOH-organic solvent to form tertiary symmetrical and mixed phosphine oxides among which tris(prop-2-enyl)-, bis(prop-2-enyl)[(E)-prop-1-enyl]-, bis(prop-2-enyl)[(Z)-prop-1-enyl]-, (prop-2-enyl)[(E)-prop-1-enyl][(Z)-prop-1-enyl]-, bis[(E)-prop-1-enyl](prop-2-enyl)-, bis[(Z)-prop-1-enyl](prop-2-enyl)-, tris-[(E)-prop-1-enyl]-, and bis[(E)-prop-1-enyl][(Z)-prop-1-enyl]phosphine oxides were identified. The conditions (room temperature, 60% aqueous KOH-dioxane) allowing preparation from white phosphorus and allyl bromide of tris(prop-2-enyl)- and bis(prop-2-enyl)[(E)-prop-1-enyl]phosphine

S. F. Malysheva; B. G. Sukhov; N. K. Gusarova; A. V. Afonin; S. I. Shaikhudinova; T. I. Kazantseva; N. A. Belogorlova; V. A. Kuimov; G. V. Plotnikova; B. A. Trofimov

2004-01-01

146

Thermochromic luminescence of copper iodide clusters: the case of phosphine ligands.  

PubMed

Three copper(I) iodide clusters coordinated by different phosphine ligands formulated [Cu(4)I(4)(PPh(3))(4)] (1), [Cu(4)I(4)(Pcpent(3))(4)] (2), and [Cu(4)I(4)(PPh(2)Pr)(4)] (3) (PPh(3) = triphenylphosphine, Pcpent(3) = tricyclopentylphosphine, and PPh(2)Pr = diphenylpropylphosphine) have been synthesized and characterized by (1)H and (31)P NMR, elemental analysis and single crystal X-ray diffraction analysis. They crystallize in different space groups, namely, monoclinic P21/c, cubic Pa ?3, and tetragonal I ?42m for 1, 2, and 3, respectively. The photoluminescence properties of clusters 1 and 3 show reversible luminescence thermochromism with two highly intense emission bands whose intensities are temperature dependent. In accordance to Density Functional Theory (DFT) calculations, these two emission bands have been attributed to two different transitions, a cluster centered (CC) one and a mixed XMCT/XLCT one. Cluster 2 does not exhibit luminescence variation in temperature because of the lack of the latter transition. The absorption spectra of the three clusters have been also rationalized by time dependent DFT (TDDFT) calculations. A simplified model is suggested to represent the luminescence thermochromism attributed to the two different excited states in thermal equilibrium. In contrast with the pyridine derivatives, similar excitation profiles and low activation energy for these phosphine-based clusters reflect high coupling of the two emissive states. The effect of the Cu-Cu interactions on the emission properties of these clusters is also discussed. Especially, cluster 3 with long Cu-Cu contacts exhibits a controlled thermochromic luminescence which is to our knowledge, unknown for this family of copper iodide clusters. These phosphine-based clusters appear particularly interesting for the synthesis of original emissive materials. PMID:21957984

Perruchas, Sandrine; Tard, Cédric; Le Goff, Xavier F; Fargues, Alexandre; Garcia, Alain; Kahlal, Samia; Saillard, Jean-Yves; Gacoin, Thierry; Boilot, Jean-Pierre

2011-11-01

147

Phosphine-substituted sterically encumbered pyrrolyl ligands - synthesis and reactivity studies.  

PubMed

The sterically encumbered pyrrolyl KPyr(tBu2) (1-K, Pyr(tBu2) = 2,5-(Me3C)2C4H2N) reacts with PCl3, (iPr)2PCl and Ph2PCl exclusively at the C3-position to yield a series of phosphine-substituted pyrroles HPyr(tBu2R) (R = PCl2 (2-H), (iPr)2P (4-H) and Ph2P (5-H)). Pyrrole 2-H can further be functionalized with MeLi (3 equiv.) to yield LiPyr(tBu2PMe2) (3-Li). The coordination chemistry of these phosphine-substituted pyrroles was explored and the resulting complexes were characterized by various spectroscopic techniques and in some cases using single crystal X-ray diffraction. The neutral pyrroles 4-H and 5-H react cleanly with [Mo(CO)6] to form the ?P-coordinate complexes 4-H-Mo(CO)5 and 5-H-Mo(CO)5, respectively. IR spectroscopy of these complexes shows that C3-substitution barely changes the ?-acceptor properties of the phosphine moiety. The ?(5)-coordination was achieved when pyrrolides 4-K and 5-K were reacted with [Mn(CO)5Br] to give 4-Mn(CO)3 and 5-Mn(CO)3, respectively. The energy of the HOMOs in these three legged-piano stool complexes decreases on PPh2-substitution (5-Mn(CO)3) stabilizing the Mn-CO bonds, whereas the inverse effect is noticed for P(iPr)2-substitution (4-Mn(CO)3). PMID:24085269

Kreye, Markus; Runyon, Jason W; Freytag, Matthias; Jones, Peter G; Walter, Marc D

2013-12-28

148

Bright electroluminescence from a chelate phosphine oxide Eu III complex with high thermal performance  

Microsoft Academic Search

The chelate phosphine oxide ligand 1,8-bis(diphenylphosphino)naphthalene oxide (NaPO) was used to prepare complex 1 tris(2-thenoyltrifluoroacetonate)(1,8-bis(diphenylphosphino)naphthalene oxide)europium(III). The rigid structure of NaPO makes 1 have more compact structure resulting in a temperature of glass transition as high as 147 °C, which is the highest in luminescent EuIII complexes, and a higher decomposition temperature of 349 °C. The improvement of carrier transfer ability of

Hui Xu; Kun Yin; Lianhui Wang; Wei Huang

2008-01-01

149

Solvent extraction of rare-earth metals with bis(2-ethylhexyl)phosphinic acid  

Microsoft Academic Search

The extraction behavior of tervalent rare-earth metals (Ln) using a heptane solution containing bis(2-ethylhexyl)phosphinic\\u000a acid (PIA-8, HR) from 0.1?mol\\/dm3 sodium perchlorate media was studied. The pH0.5 values and separation factors obtained were compared among the metals. The stoichiometry of the extracted species and the\\u000a extraction constants for the present aqueous\\/heptane system were determined by slope analysis. It is demonstrated that

Yukio Nagaosa; Yao Binghua

1997-01-01

150

Photochemical dimerization and functionalization of alkanes, ethers, primary and secondary alcohols, phosphine oxides and silanes  

DOEpatents

The space-time yield and/or the selectivity of the photochemical dimerization of alkanes, ethers, primary and secondary alcohols, phosphine oxides and primary, secondary and tertiary silanes with Hg and U.V. light is enhanced by refluxing the substrate in the irradiated reaction zone at a temperature at which the dimer product condenses and remains condensed promptly upon its formation. Cross-dimerization of the alkanes, ethers and silanes with primary alcohols is disclosed, as is the functionalization to aldehydes of the alkanes with carbon monoxide.

Crabtree, R.H.; Brown, S.H.

1989-10-17

151

Methylene-bis[(aminomethyl)phosphinic acids]: synthesis, acid-base and coordination properties.  

PubMed

Three symmetrical methylene-bis[(aminomethyl)phosphinic acids] bearing different substituents on the central carbon atom, (NH(2)CH(2))PO(2)H-C(R(1))(R(2))-PO(2)H(CH(2)NH(2)) where R(1) = OH, R(2) = Me (H(2)L(1)), R(1) = OH, R(2) = Ph (H(2)L(2)) and R(1),R(2) = H (H(2)L(3)), were synthesized. Acid-base and complexing properties of the ligands were studied in solution as well as in the solid state. The ligands show unusually high basicity of the nitrogen atoms (log K(1) = 9.5-10, log K(2) = 8.5-9) if compared with simple (aminomethyl)phosphinic acids and, consequently, high stability constants of the complexes with studied divalent metal ions. The study showed the important role of the hydroxo group attached to the central carbon atom of the geminal bis(phosphinate) moiety. Deprotonation of the hydroxo group yields the alcoholate anion which tends to play the role of a bridging ligand and induces formation of polynuclear complexes. Solid-state structures of complexes [H(2)N=C(NH(2))(2)][Cu(2)(H(-1)L(2))(2)]CO(3)·10H(2)O and Li(2)[Co(4)(H(-1)L(1))(3)(OH)]·17.5H(2)O were determined by X-ray diffraction. The complexes show unexpected geometries forming dinuclear and cubane-like structures, respectively. The dinuclear copper(II) complex contains a bridging ?(2)-alcoholate group with the (-)O-P(=O)-CH(2)-NH(2) fragments of each ligand molecule chelated to the different central ion. In the cubane cobalt(II) complex, one ?(3)-hydroxide and three ?(3)-alcoholate anions are located in the cube vertices and both phosphinate groups of one ligand molecule are chelating the same cobalt(II) ion while each of its amino groups are bound to different neighbouring metal ions. All such three metal ions are bridged by the alcoholate group of a given ligand. PMID:23208292

David, Tomáš; Procházková, So?a; Havlí?ková, Jana; Kotek, Jan; Kubí?ek, Vojt?ch; Hermann, Petr; Lukeš, Ivan

2013-02-21

152

Polydentate phosphine oxides as external electron donors for titanium-magnesium catalysts for propylene polymerization  

Microsoft Academic Search

The possibility of using R\\u000a n\\u000a P(O)(CH2OR?)3—n\\u000a (R = alkyl, R? = methyl or acyl, n = 0–2) polydentate phosphine oxides as external electron donors for the titanium-magnesium catalysts for isotactic polypropylene\\u000a synthesis is demonstrated for the first time. The kinetics of propylene polymerization in liquid monomer at 70°C and the isotacticity\\u000a and molecular-weight characteristics of the resulting polypropylene are

O. I. Kudinova; T. E. Kron; T. A. Ladygina; A. N. Kozhevnikov; E. S. Petrov; L. A. Novokshonova

2010-01-01

153

Phosphine Oxides as Stabilizing Ligands for the Palladium-Catalyzed Cross-Coupling of Potassium Aryldimethylsilanolates  

PubMed Central

The palladium-catalyzed cross-coupling reaction of potassium (4-methoxyphenyl)dimethylsilanolate (K+1?) with aryl bromides has been demonstrated using triphenylphosphine oxide as a stabilizing ligand. Unsymmetrical biaryls can be prepared from a variety of aryl bromides in good yield with short reaction times. Qualitative kinetics studies compared effects of different phosphine oxides on the rate of cross-coupling and established the beneficial effect of these ligands in the reaction of electron-rich arylsilanolates. The improved yield and reproducibility of the cross-coupling of several bromides was demonstrated by direct comparison of reactions performed with and without triphenylphosphine oxide under non-rigorous exclusion of oxygen.

Denmark, Scott E.; Smith, Russell C.; Tymonko, Steven A.

2012-01-01

154

Complexation of metal ions with TRAP (1,4,7-triazacyclononane phosphinic acid) ligands and 1,4,7-triazacyclononane-1,4,7-triacetic acid: phosphinate-containing ligands as unique chelators for trivalent gallium.  

PubMed

Three phosphinic acid 1,4,7-triazacyclononane (TACN) derivatives bearing methylphosphinic (TRAP-H), methyl(phenyl)phosphinic (TRAP-Ph), or methyl(hydroxymethyl)phosphinic acid (TRAP-OH) pendant arms were investigated as members of a new family of efficient Ga(3+) chelators, TRAP ligands (triazacyclononane phosphinic acids). Stepwise protonation constants of ligands and stability constants of their complexes with Ga(3+), selected divalent metal, and Ln(3+) ions were determined by potentiometry. For comparison, equilibrium data for the metal ion-NOTA (1,4,7-triazacyclononane-1,4,7-triacetic acid) systems were redetermined. These ligands exhibit high thermodynamic selectivity for Ga(3+) over the other metal ions (log K(GaL) - log K(ML) = 7-9) and a selective complexation of smaller Mg(2+) over Ca(2+). Stabilities of the Ga(3+) complexes are dependent on the basicity of the donor atoms: [Ga(NOTA)] (log K(GaL) = 29.6) > [Ga(TRAP-OH)] (log K(GaL) = 23.3) > [Ga(TRAP-H)] (log K(GaL) = 21.9). The [Ga(TRAP-OH)] complex exhibits unusual reversible rearrangement of the "in-cage" N(3)O(3) complex to the "out-of-cage" O(6) complex. The in-cage complex is present in acidic solutions, and at neutral pH, Ga(3+) ion binds hydroxide anion, induces deprotonation and coordination of the P-hydroxymethyl group(s), and moves out of the macrocyclic cavity; the hypothesis is supported by a combination of results from potentiometry, multinuclear nuclear magnetic resonance spectrometry, and density functional theory calculations. Isomerism of the phosphinate Ga(3+) complexes caused by a combination of the chelate ring conformation, the helicity of coordinated pendant arms, and the chirality of the coordinated phosphinate groups was observed. All Ga(3+) complexes are kinetically inert in both acidic and alkaline solutions. Complex formation studies in acidic solutions indicate that Ga(3+) complexes of the phosphinate ligands are formed quickly (minutes) and quantitatively even at pH <2. Compared to common Ga(3+) chelators (e.g., 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) derivatives), these novel ligands show fast complexation of Ga(3+) over a broad pH range. The discussed TRAP ligands are suitable alternatives for the development of (68)Ga radiopharmaceuticals. PMID:22221285

Šime?ek, Jakub; Schulz, Martin; Notni, Johannes; Plutnar, Jan; Kubí?ek, Vojt?ch; Havlí?ková, Jana; Hermann, Petr

2012-01-01

155

Tri(pyridylmethyl)phosphine: the elusive congener of TPA shows surprisingly different coordination behavior.  

PubMed

Tri(pyridylmethyl)phosphine (TPPh), the remarkably elusive congener of tri(pyridylmethyl)amine (TPA), has been prepared, as well as the relative tri(N-methyl-pyridylamino)phosphine (TPAMP). The coordination properties of these new ligands have been evaluated for chromium(III), iron(II), and ruthenium(II) complexes and compared with the related TPA complexes. In all cases, a different coordination behavior has been observed whereby TPPh and TPAMP always act as tridentate ligands. A chromium(III) complex [Cr(TPPh)Cl3] has been prepared, which has shown low ethylene oligomerization activity. Octahedral low spin iron(II) complexes [Fe(TPPh)2](2+) and [Fe(TPAMP)2](2+) were obtained with two ligands bound to the metal center. Ruthenium(II) chloro complexes of TPA and TPPh undergo ligand exchange reactions in acetonitrile, and the ruthenium(II) complex [Ru(MeCN)2(TPA)](2+) can be oxidized by m-CPBA in acetonitrile to give a transient ruthenium(IV) oxo complex [Ru(O)(MeCN)(TPA)](2+). Attempts to generate high valent ruthenium(IV) oxo TPPh or TPAMP complexes could not be achieved, probably due to insufficient stabilization by these strong field ligands. PMID:23701515

Whiteoak, Christopher J; Nobbs, James D; Kiryushchenkov, Evgeny; Pagano, Sandro; White, Andrew J P; Britovsek, George J P

2013-06-17

156

Theoretical studies of blue phosphorescent iridium(III) complexes with phenylpyrazole and phosphines.  

PubMed

New blue emitting mixed ligand iridium(III) complexes comprising one cyclometalating, two phosphines trans to each other such as Ir(dppz)(PPhMe2)2(H)(C1) and Ir(dppz)(PPhMe2)2(H)(CN), [dppz = 3,5-Diphenylpyrazole] were studied to tune the phosphorescence wavelength to the deep blue region and to enhance the luminescence efficiencies. To achieve deep blue emission and increase the emission efficiency, the following must occur: (1) substitution of phenyl group on the 3-position of the pyrazole ring that lower the triplet energy enough that the quenching channel is not thermally accessible, (2) changing ancillary ligands coordinated to iridium atom to phosphine and cyano groups known as very strong field ligands. Using the density functional theory (DFT) and time-dependent DFT method calculations on the ground and excited states of the complexes, we have studied how the ancillary ligand influences the emission peak as well as MLCT transition efficiency. It is showed that the strong-field ancillary ligand such as CN, PPhMe2 alters the energy gap mainly by changing the highest occupied molecular orbitals (HOMO) energy level. Their inclusion in the coordination sphere can increase the energy gap to achieve the hypsochromic shift in emission color and also lower the triplet energy level to avoid the thermal quenching. PMID:22852392

Park, Se Won; Chang, Dong Min; Kim, Young Sik

2012-05-01

157

Asymmetric Hydroformylation of Heterocyclic Olefins Catalyzed by Chiral Phosphine-Phosphite-Rh(I) Complexes.  

PubMed

Asymmetric hydroformylation of heterocyclic olefins catalyzed by phosphine-phosphite-Rh(I) complexes has been investigated. Hydroformylation of symmetrical heterocyclic olefins such as 2,5-dihydrofuran, 3-pyrroline derivatives, and 4,7-dihydro-1,3-dioxepin derivatives afforded the optically active aldehydes as single products in 64-76% ee. Unsymmetrical substrates such as 2,3-dihydrofuran and N-(tert-butoxycarbonyl)-2-pyrroline gave a mixture of regioisomers. From N-(tert-butoxycarbonyl)-2-pyrroline was obtained N-(tert-butoxycarbonyl)pyrrolidine-2-carbaldehyde in 97% ee. The hydroformylation products from 2,5-dihydrofuran and N-(tert-butoxycarbonyl)-3-pyrroline have the opposite configurations to those from 2,3-dihydrofuran and N-(tert-butoxycarbonyl)-2-pyrroline, respectively, with the same catalyst. The new phosphine-phosphite ligand (R,S)-3,3'-Me(2)-BINAPHOS [= (R)-2-(diphenylphosphino)-1,1'-binaphthalen-2'-yl (S)-3,3'-dimethyl-1,1'-binaphthalene-2,2'-diyl phosphite] was prepared and its hydridorhodium complex was characterized by NMR spectroscopy. Using (R,S)-3,3'-Me(2)-BINAPHOS as a ligand, the enantioselectivity was improved for some substrates. In addition, higher catalytic activity was observed with this ligand for most of the substrates employed. PMID:11671748

Horiuchi, Toshihide; Ohta, Tetsuo; Shirakawa, Eiji; Nozaki, Kyoko; Takaya, Hidemasa

1997-06-27

158

Pillar[5]arenes bearing phosphine oxide pendents as Hg(2+) selective receptors.  

PubMed

Pillar[5]arenes bearing ten phosphine oxide groups (1a-e), as analogs of their corresponding calix[4]arene-based phosphine oxide, have demonstrated intriguing recognition performance for some representative heavy metal cations including Co(2+), Cu(2+), Ni(2+), Zn(2+), Cd(2+), Pb(2+), Ag(2+) and Hg(2+) compared to their acyclic species (2a-e). Their extraction abilities toward these cations were evaluated by the solvent extraction method. The extraction results revealed that 1a-e were efficient and selective cation receptors for Hg(2+) over other selected cations. In addition, the complexation behavior of 1a-e for Hg(2+) was also investigated by using NMR and UV-vis techniques. The pillarareen receptors have been first used in the determination of inorganic mercury in natural water by inductively coupled plasma atomic emission spectrometry (ICP-AES), after back-extracting into aqueous phase with 3molL(-1) HCl and 1% CS(NH2)2 solution. PMID:24840451

Jia, Yiming; Fang, Yuyu; Li, Yan; He, Lutao; Fan, Wenhua; Feng, Wen; Yang, Yuanyou; Liao, Jiali; Liu, Ning; Yuan, Lihua

2014-07-01

159

Atomistic Simulations of Perfluoro Phosphonic and Phosphinic Acid Membranes and Comparisons to Nafion  

SciTech Connect

We used classical molecular dynamics (MD) simulations to investigate the nanoscale morphology and proton transport properties of perfluoro phosphonic (FPA) and phosphinic acid (FPA-I) membranes as they are being considered for use in low temperature fuel cells. We systematically investigated these properties as a function of the hydration level. The changes in nanostructure, in transport dynamics of water and hydronium ions, and in water network percolation were extracted from MD simulations and compared with Nafion. Phosphonic and phosphinic acid moieties in FPA and FPA-I, have lower acidity than sulfonic acid in Nafion, yet the diffusion of water was observed to be faster in FPA and FPA-I than in Nafion, particularly at low hydration levels. However this did not give rise to notable differences in hydronium ion diffusion and water network percolation for these membranes over Nafion. Similar observations were also reported by our group recently in a study of perfluoro-sulfonyl imide membranes carrying stronger super-acids than sulfonic acid of Nafion. These findings together suggest no strong apparent correlation between the acidity strength of the functional acid groups and the dynamics of water and hydronium ions in hydrated polymer electrolyte membranes (PEMs) with similar fluorocarbon backbones and acidic group-carrying side chains. This work was supported by the US Department of Energy Basic Energy Sciences' Chemical Sciences, Geosciences & Biosciences Division. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.

Idupulapati, Nagesh B.; Devanathan, Ramaswami; Dupuis, Michel

2011-03-31

160

Heterobimetallic catechol-phosphine complexes with palladium and a group-13 element: structural flexibility and dynamics.  

PubMed

Group-13 metal acetylacetonates [M(acac)3] (M = Al, Ga, In) or Al(OiPr)3 react with a complex [Pd(catphosH)2] that may act as chelating ligand towards a second metal, or with a mixture of catechol phosphine (catphosH2) and [PdCl2(cod)], to give heterometallic complexes featuring either dinuclear M(catphos)2Pd or trinuclear M{(catphos)2Pd}2 motifs. Characterisation of the products by crystallographic and solution NMR studies gives insight into the structural diversity and flexibility of the coordination environments of the group-13 elements and their impact on the stability of the multinuclear complexes. The results indicate that gallium and indium are the most suitable elements for the stabilisation of di- and trinuclear assemblies, respectively. Dynamic NMR spectroscopy allowed to follow the dynamic averaging of the coordination environments of the four distinguishable catechol phosphines in the indium complex [M{(catphos)2Pd}2]H. The results revealed that the isomerisation follows a complicated pathway involving several distinguishable proton transfer steps, and allowed to propose a mechanistic explanation for the observed isomerisation. PMID:24802543

Bauer, G; Nieger, M; Gudat, D

2014-06-21

161

Tertiary arsine-stabilised arsenium salts: syntheses and comparisons with phosphine analogues.  

PubMed

The first tertiary arsine-stabilised arsenium salts, [(L)AsMePh]OTf (L = Ph3As, Me2PhAs, [2-(MeOCH2)C6H4]Ph2As, [2-(MeOCH2)C6H4]Me2As), have been prepared by chloride abstraction from chloromethylphenylarsine with trimethylsilyl triflate in the presence of the arsine. The complexes have been characterised by crystallography and 1H NMR spectroscopy. The chiral cations in the complexes have structures based on the trigonal pyramid in which the arsine is coordinated orthogonally to the prochiral, six-electron MePhAs+ ion that forms the base of the pyramid. The NMR data for the complexes in dichloromethane-d2 are consistent with rapid exchange of the arsine on the arsenium ion, even at 183 K. The corresponding phosphine-stabilised complexes are considerably more stable than their arsine counterparts in dichloromethane-d2 with the free energy of activation DeltaG = ca. 60 kJ mol(-1) being calculated for phosphine exchange in [(Me2PhP)AsMePh]OTf at 281 K; for [(Me2[2-(MeOCH2)C6H4]P)AsMePh]OTf in the same solvent, DeltaG = ca. 70 kJ mol(-1) at 323 K. PMID:18461204

Kilah, Nathan L; Weir, Michelle L; Wild, S Bruce

2008-05-14

162

Efficacies of spinosad and a combination of chlorpyrifos-methyl and deltamethrin against phosphine-resistant Rhyzopertha dominica (Coleoptera: Bostrichidae) and Tribolium castaneum (Coleoptera: Tenebrionidae) on wheat.  

PubMed

Highly phosphine-resistant populations of Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae) and Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) have recently been found in Oklahoma grain storage facilities. These findings necessitate development of a phosphine resistance management strategy to ensure continued effective use of phosphine. Therefore, we investigated the efficacies of two grain insecticides, namely, spinosad applied at label rate of 1 ppm and a mixture of chlorpyrifos-methyl and deltamethrin applied at label rates of 3 and 0.5 ppm, respectively, against highly phosphine-resistant R. dominica and T. castaneum. Adult mortality and progeny production suppression of spinosad- or chlorpyrifos-methyl + deltamethrin mixture-treated wheat that had been stored for 2, 84, 168, 252, and 336 d posttreatment were assessed. We found that both spinosad and chlorpyrifos-methyl + deltamethrin were effective against phosphine-resistant R. dominica and caused 83-100% mortality and also caused total progeny production suppression for all storage periods. Spinosad was not effective against phosphine-resistant T. castaneum; the highest mortality observed was only 3% for all the storage periods. Chlorpyrifos-methyl + deltamethrin was effective against phosphine-resistant T. castaneum only in treated wheat stored for 2 and 84 d, where it caused 93-99% mortality. However, chlorpyrifos-methyl + deltamethrin was effective and achieved total suppression of progeny production in T. castaneum for all the storage periods. Spinosad was not as effective as chlorpyrifos-methyl + deltamethrin mixture at suppressing progeny production of phosphine-resistant T. castaneum. These two insecticides can be used in a phosphine resistance management strategy for R. dominica and T. castaneum in the United States. PMID:24224266

Bajracharya, N S; Opit, George P; Talley, J; Jones, C L

2013-10-01

163

Carbonylation of terminal alkynes catalysed by Pd complexes in combination with tri(2-furyl)phosphine and methanesulfonic acid  

Microsoft Academic Search

Pd(OAc)2 in combination with tri(2-furyl)phosphine and methanesulfonic acid is an efficient catalyst for the alkoxycarbonylation of 1-alkynes. Fairly good reaction rates are obtained under mild conditions (50–80°C and P(CO)=20 bar) with high regioselectivity (ca. 95%) towards the formation of 2-substituted acrylic ester.

Alberto Scrivanti; Valentina Beghetto; Monica Zanato; Ugo Matteoli

2000-01-01

164

Chiral multifunctional thiourea-phosphine catalyzed asymmetric [3 + 2] annulation of Morita-Baylis-Hillman carbonates with maleimides  

PubMed Central

Summary We have developed a multifunctional thiourea-phosphine catalyzed asymmetric [3 + 2] annulation of Morita–Baylis–Hillman (MBH) carbonates with maleimides, which can efficiently construct functionalized cyclopentenes bearing three contiguous stereocenters in moderate to excellent yields and excellent diastereo- and enantioselectivities. A plausible mechanism has been also proposed on the basis of control experiments and previous literature.

Deng, Hong-Ping; Wang, De; Wei, Yin

2012-01-01

165

Phosphine-catalyzed Rauhut-Currier domino reaction: a facile strategy for the construction of carbocyclic spirooxindoles skeletons.  

PubMed

Push-over: A novel domino reaction of activated conjugated dienes and methyleneindolinones incorporates a phosphine-catalyzed intermolecular Rauhut-Currier to form two C-C bonds and a quaternary carbon center. This method can be used to synthesize spirocyclopenteneoxindoles skeletons, which are potential building blocks for biologically active compounds. PMID:23813882

Hu, Chongchong; Zhang, Qinglong; Huang, You

2013-09-01

166

Chiral diene-phosphine tridentate ligands for rhodium-catalyzed asymmetric cycloisomerization of 1,6-enynes.  

PubMed

Asymmetric cycloisomerization of nitrogen-bridged 1,6-enynes proceeded in the presence of a cationic rhodium complex coordinated with a chiral diene/phosphine tridentate ligand to give high yields of chiral 3-azabicyclo[4.1.0]heptenes with high enantioselectivity. PMID:21688864

Nishimura, Takahiro; Maeda, Yuko; Hayashi, Tamio

2011-07-15

167

Copper- and phosphine-ligand-free palladium-catalyzed direct allylation of electron-deficient polyfluoroarenes with allylic chlorides.  

PubMed

Simply id(all)ylic: a copper- and phosphine-ligand-free Pd-catalyzed direct allylation of electron-deficient polyfluoroarenes with allylic chlorides and the reaction mechanism are described. The simple catalytic system, broad substrate scope, and excellent functional-group compatibility of this protocol provides a useful and facile access to allylated polyfluoroarenes. PMID:23055245

Yu, Yan-Bo; Fan, Shilu; Zhang, Xingang

2012-11-12

168

Synthesis of Fmoc-Gly-Ile Phosphinic Pseudodipeptide: Residue Specific Conditions for Construction of Matrix Metalloproteinase Inhibitor Building Blocks  

PubMed Central

The efficient synthesis of an Fmoc-Gly-Ile phosphinic pseudodipeptide was desired as an eventual building block for construction of matrix metalloproteinase inhibitors. A Michael-type addition reaction of bis(tri-methylsilyl) phosphonite with the appropriate acrylate generated the pseudodipeptide bond. Additional of adamantyl (Ad) protection by our prior route (reaction of in situ generated phosphinic acid chloride with the sodium salt of adamantanol) was surprisingly inefficient. Adamantyl protection was achieved in high yield by refluxing the phosphinic acid, Ag2O, and 1-AdBr in chloroform. Subsequently a concise one-pot three-step reaction comprising a double deprotection of the N- and C-termini under catalytic hydrogenation conditions followed by selective protection of the N-terminus with an Fmoc group yielded Fmoc-NHCH2PO(OAd)CH2CH(2-butyl)CO2H in 41 % overall yield. These results indicate that, as the diversity of phosphinic pseudodipeptides is increased to create selective matrix metalloproteinase inhibitors, different synthetic pathways may be required for efficient building block preparation.

Bhowmick, Manishabrata

2012-01-01

169

Phosphine resistance in the rust red flour beetle, Tribolium castaneum (Coleoptera: Tenebrionidae): inheritance, gene interactions and fitness costs.  

PubMed

The recent emergence of heritable high level resistance to phosphine in stored grain pests is a serious concern among major grain growing countries around the world. Here we describe the genetics of phosphine resistance in the rust red flour beetle Tribolium castaneum (Herbst), a pest of stored grain as well as a genetic model organism. We investigated three field collected strains of T. castaneum viz., susceptible (QTC4), weakly resistant (QTC1012) and strongly resistant (QTC931) to phosphine. The dose-mortality responses of their test- and inter-cross progeny revealed that most resistance was conferred by a single major resistance gene in the weakly (3.2×) resistant strain. This gene was also found in the strongly resistant (431×) strain, together with a second major resistance gene and additional minor factors. The second major gene by itself confers only 12-20× resistance, suggesting that a strong synergistic epistatic interaction between the genes is responsible for the high level of resistance (431×) observed in the strongly resistant strain. Phosphine resistance is not sex linked and is inherited as an incompletely recessive, autosomal trait. The analysis of the phenotypic fitness response of a population derived from a single pair inter-strain cross between the susceptible and strongly resistant strains indicated the changes in the level of response in the strong resistance phenotype; however this effect was not consistent and apparently masked by the genetic background of the weakly resistant strain. The results from this work will inform phosphine resistance management strategies and provide a basis for the identification of the resistance genes. PMID:22363681

Jagadeesan, Rajeswaran; Collins, Patrick J; Daglish, Gregory J; Ebert, Paul R; Schlipalius, David I

2012-01-01

170

Microstructure degradation of YSZ in Ni/YSZ anodes of SOFC operated in phosphine-containing fuels  

SciTech Connect

The interaction of trace (ppm) phosphine with the nickel/yttria stabilized zirconia (YSZ) anode of commercial solid oxide fuel cells has been investigated and evaluated for both synthesis gas and hydrogen fuels in an effort to examine P–Y reactions. The Ni poisoning effects reported in literature were confirmed and degradation was examined by electrochemical methods and post-test microstructural and chemical analyses. The results indicate that P-induced degradation rates and mechanisms are fuel dependent and that degradation of cells operated in synthesis gas (syngas) with phosphine is more severe than that of cells operated in hydrogen with phosphine. As reported in published literature, a cell operated in syngas containing 10 ppm phosphine demonstrated significant microstructural degradation within the Ni phase, including formation of Ni–P phases concentrated on the outer layer of the anode and significant pitting corrosion in the Ni grains. In this research, a previously undetected YPO{sub 4} phase is observed at the YSZ/YSZ/Ni triple grain junctions located at the interface with the YSZ electrolyte. Tetragonal YSZ (t-YSZ) and cubic-YSZ (c-YSZ) domains with sizes of several tens of nanometers are also newly observed along the Ni/YSZ interface. These observations contrast with data obtained for a cell operated in dry hydrogen with phosphine, where no YPO{sub 4} phase is observed and the alternating t-YSZ and c-YSZ domains at the Ni/YSZ interface are smaller with typical sizes of 5–10 nm. The data imply that electrolyte attack by P is a potentially debilitating mode of degradation in SOFC anodes, and that the associated reaction mechanisms and rates are worthy of further examination.

Chen, Yun; Chen, Song; Hackett, Gregory; Finklea, Harry; Zondlod, John; Celik, Ismail; Song, Xueyan; Gerdes, Kirk

2013-03-07

171

Synthesis and Microwave Spectra of Simple Phosphines, Possible Components of the Atmospheres of the Giant Planets  

NASA Astrophysics Data System (ADS)

The atmospheres of Jupiter and Saturn mainly contain hydrogen (H2), helium (He) and, at a lower concentration, several hydrocarbons like methane (CH4), ethane (H3C-CH3), benzene (C6H6), acetylene (HC? CH), butadiyne (HC? C-C? CH), .... Polyatomic components with a heteroatom are also present: ammonia (NH3), phosphine (PH3), germane (GeH4), arsine (AsH3), dihydrogen sulfide (SH2), ... Laboratory photolysis of these heterocompounds with hydrocarbons leads to numerous products which are, for the two most important parts, adducts (1 + 1 adducts) and oxidized adducts (1 + 1 adducts with the lost of dihydrogen). As a simple example the photolysis of ammonia in the presence of propene leads to two major compounds: the n-propylphosphine (H3C-CH2-CH2-PH2) and the allylphosphine (H2C=CH-CH2-PH2). On the basis of the photoproducts characterized in our lab experiments,1 we recorded the microwave spectra of such phosphines. We report here the MW spectra of allyl- (H2C=CH-CH2-PH2), propargyl- (HC? C-CH2-PH2). and allenylphosphine (H2C=C=CH-PH2).2 For these compounds, we observed some rotamers which complicate the spectra but, more importantly, which will complicate their detection in the planetary atmospheres. To continue on this idea, we will also describe the spectra we recently published on a 3-butenyl compound (3-buteneselenol) to show how the high number of rotamers added to many isotopomers highly increases the difficulty to detect such species in planetary atmospheres if they are present. Many studies on the synthesis and recording spectra of various simple germanes, thiols, arsines and phosphines are currently under progress in our laboratories. The particular procedures used to synthesize these unstable or pyrophoric compounds will be described. 1 Adv. Space Res. 1995, 16, 85-92 ; 1997, 19, 1093-1102. 2 Inorg. Chem. 2001, 40, 3719-3724 ; J. Phys. Chem. A 2002, 106, 11481-11487 ; 2003, 107, 1403.

Guillemin, J. C.; Petitprez, D.; Demaison, J.; Wlodarczak, G.; Mollendal, H.

172

Chiral bisphosphinite metalloligands derived from a P-chiral secondary phosphine oxide.  

PubMed

Interaction of PdCl(2)(MeCN)(2) with 2 equiv of (S(P))-(t)BuPhP(O)H (1H) followed by treatment with Et(3)N gave [Pd((1)(2)H)](2)(micro-Cl)(2) (2). Reaction of 2 with Na[S(2)CNEt(2)] or K[N(PPh(2)S)(2)] afforded Pd[(1)(2)H](S(2)CNEt(2)) (3) or Pd[(1)(2)H)[N(PPh(2)S)(2)] (4), respectively. Treatment of 3 with V(O)(acac)(2) (acac = acetylacetonate) and CuSO(4) in the presence of Et(3)N afforded bimetallic complexes V(O)[Pd(1)(2)(S(2)CNEt(2))](2) (5) or Cu[Pd(1)(2)(S(2)CNEt(2))](2) (6), respectively. X-ray crystallography established the S(P) configuration for the phosphinous acid ligands in 3 and 6, indicating that 1H binds to Pd(II) with retention of configuration at phosphorus. The geometry around Cu in 6 is approximately square planar with the average Cu-O distance of 1.915(3) A. Treatment of 2 with HBF(4) gave the BF(2)-capped compound [Pd((1)(2)BF(2))](2)(micro-Cl)(2) (7). The solid-state structure of 7 containing a PdP(2)O(2)B metallacycle has been determined. Chloride abstraction of 7 with AgBF(4) in acetone/water afforded the aqua compound [Pd((1)(2)BF(2))(H(2)O)(2)][BF(4)] (8) that reacted with [NH(4)](2)[WS(4)] to give [Pd((1)(2)BF(2))(2)](2)[micro-WS(4)] (9). The average Pd-S and W-S distances in 9 are 2.385(3) and 2.189(3) A, respectively. Treatment of [(eta(6)-p-cymene)RuCl(2)](2) with 1H afforded the phosphinous acid adduct (eta(6)-p-cymene)RuCl(2)(1H) (10). Reduction of [CpRuCl(2)](x)() (Cp = eta(5)-C(5)Me(5)) with Zn followed by treatment with 1H resulted in the formation of the Zn(II) phosphinate complex [(CpRu(eta(6)-C(6)H(5)))(t)BuPO(2))](2)(ZnCl(2))(2) (11) that contains a Zn(2)O(4)P(2) eight-membered ring. PMID:15285668

Chan, Eddie Y Y; Zhang, Qian-Feng; Sau, Yiu-Keung; Lo, Samuel M F; Sung, Herman H Y; Williams, Ian D; Haynes, Richard K; Leung, Wa-Hung

2004-08-01

173

Computational studies of complexation of nitrous oxide by borane-phosphine frustrated Lewis pairs.  

PubMed

Computational studies of complexes Ar(3)B-ONN-PR(3) derived from reactions between borane-phosphine frustrated Lewis pairs and N(2)O reveal several interesting facets. Natural resonance theory calculations support a change in the preferred resonance structure as the Lewis acidity of the borane increases. Potential constitutional isomers where phosphorus binds to oxygen and boron to nitrogen are predicted to be unstable with respect to loss of phosphine oxide and free N(2). Other constitutional isomers represent stationary points on the potential energy surface; most are considerably less stable than the observed complexes, but one is predicted to be as stable. This arises because the dominant resonance form combines alternating charge with the presence of a stabilizing NO double bond. The relationship between Lewis acidity and complex formation for a variety of boranes was explored; the results are consistent with the idea that greater Lewis acidity stabilizes both classical and frustrated Lewis acid-base pairs, but to differing degrees such that both types can entrap N(2)O. Calculations addressing the mechanism of complex formation suggest that N(2)O binds first through the nitrogen to the phosphine phosphorus of the FLP, whereupon boron coordinates the oxygen atom. Studies of the mechanism of the degenerate exchange reaction between (4-F-H(4)C(6))(3)B-ONN-P(t-Bu)(3) and B(C(6)H(4)-4-F)(3), involves a "transition state", with relatively short B-O distances, and so resembles a classical I(a) process. The process involves two barriers, one associated with bringing the incoming borane into proximity with the oxygen, and the other associated with isomerising from a ladle-shaped cis-trans ct conformer to the observed trans-trans tt-type structure. The overall barrier for degenerate exchange was predicted to be between 65 and 110 kJ mol(-1), in fair agreement with experiment. Similar studies of the reaction between (4-F-H(4)C(6))(3)B-ONN-P(t-Bu)(3) and B(C(6)F(5))(3) indicate that this process more closely resembles a classical I(d) process, in that the "transition state" involves long B-O distances. Derivatization of the complexed NNO fragment appears possible; interaction between (F(5)C(6))(3)B-ONN-P(t-Bu)(3) and MeLi suggests stability for the ion pairs (F(5)C(6))(3)B-ON(Me)N-P(t-Bu)(3)(-)/Li(+) and (F(5)C(6))(3)B-ONN(Me)-P(t-Bu)(3)(-)/Li(+). PMID:22460739

Gilbert, Thomas M

2012-08-14

174

Synthesis of iridium and rhodium complexes with new chiral phosphine-NHC ligands based on 1,1'-binaphthyl framework and their application in asymmetric hydrogenation.  

PubMed

The first series of chiral phosphine-imidazole carbene ligands based on a 1,1'-binaphthyl framework were synthesized from (R)-2-amine-2'-(diphenylphosphino)-1,1'-binaphthyl (1) in a four-step pathway. After deprotonation of these phosphine-imidazolium salts with LiO(t)Bu, and subsequent complexation with [Ir(COD)Cl]2 and anion exchange with NaBArF, phosphine-carbene chelated iridium complexes (R)-6a and (R)-6b were obtained. Their structures have been characterized by NMR and X-ray diffraction analysis. The NHC-phosphine rhodium complex (R)-6c has been also obtained by a similar synthetic method. These iridium complexes have been applied to catalyze the asymmetric hydrogenation of alkenes to give the corresponding products in moderate to excellent conversion (up to 99%) and moderate enantioselectivities under mild conditions (up to 61% ee). PMID:23900600

Gu, Peng; Zhang, Jun; Xu, Qin; Shi, Min

2013-10-01

175

PHOSPHINE SUBSTITUTION IN n5-CYCLOPENTADIENYL-BIS-TRIPHENYLPHOSPHINECOBALT (I): EVIDENCE FOR A DISSOCIATIVE MECHANISM  

SciTech Connect

The substitution of trimethylphosphine for triphenylphosphine in {eta}{sup 5}-cyclopentadienyl-bis-triphenylphosphinecobalt(I), 1, to form {eta}{sup 5}-cyclopentadienyltrimethylphosphinetriphenylphosphinecobalt(I) was studied at -60°C in an NMR spectrometer. Kinetic measurements show the process to be first order in 1 and zero order in PMe{sub 3}; added PPh{sub 3} strongly inhibits the reaction rate. This information indicates the reaction proceeds by rapid reversible phosphine dissociation through the unsaturated CpCo(PPh{sub 3}) intermediate. The rate for generation of that intermediate, k{sub 1}, is 1.15 x 10{sup -3} sec{sup -1} while the ratio of rate constant k{sub 2} (for conversion of intermediate to products) to k{sub -1} (return to starting materials) is 4 at -60°C. Possible structures for CpCo(L) are discussed in light of recent indications that the linear structure has an open-shell electronic configuration.

Janowicz, Andrew H.; Bryndza, Henry E.; Bergman, Robert G.

1980-06-01

176

Characterizing the b?p stretching vibration in phosphorus-substituted phosphine boranes.  

PubMed

The experimental Raman spectra of three phosphorus-substituted phosphine boranes with bulky hydrocarbon substituents are presented and compared to the results of electronic structure computations by using the M06-2X method and the 6-311G(2df,?2pd) basis set. Total-energy distributions (TEDs) are calculated to describe the degree of mixing of the dative-bond stretching vibration with other simple internal coordinates. This level of theory is found to accurately reproduce the B?P stretching frequency in all three crystalline solids. The Raman spectra of five smaller B?P-containing molecules, including BH3 PH3 , are also simulated at this level of theory and compared to previous experimental results. PMID:24668930

Reinemann, Dana N; Tschumper, Gregory S; Hammer, Nathan I

2014-06-23

177

Charge transport, carrier balance, and blue electrophosphorescence in diphenyl[4-(triphenylsilyl)phenyl]phosphine oxide devices  

NASA Astrophysics Data System (ADS)

Diphenyl[4-(triphenylsilyl)phenyl]phosphine oxide (EMPA1) displays a wide highest occupied molecular orbital-lowest unoccupied molecular orbital gap (4.1 eV), singlet (4.3 eV) and triplet (3.4 eV), and an electron-dominated charge transport that follows a trap-free space charge limited model with an average electron mobility of 5.7×10-6 cm2 V-1 s-1 and a hole mobility of 1.1×10-6 cm2 V-1 s-1. At high driving voltages (>6 V), ambipolar charge transport is observed, resulting in a balanced charge density in the active layer. Highly efficient blue phosphorescent organic light-emitting diodes were realized, showing a high external quantum efficiency (21%) and a luminance efficiency of 45 cd/A using a bis[2-(4',6'-difluorophenyl)-pyridinato-N,C2']iridium(III) picolinate dopant.

Mamada, Masashi; Ergun, Selin; Pérez-Bolívar, César; Anzenbacher, Pavel

2011-02-01

178

Phosphine-Catalyzed Asymmetric Synthesis of ?-Lactones from Disubstituted Ketenes and Aldehydes.  

PubMed

In this article we describe a general catalytic procedure for the formation of ?-lactones bearing two stereogenic centers, from disubstituted ketenes and achiral aldehydes. BINAPHANE was found to display excellent enantioselectivity (?90% ee for eight examples) and good diastereoselectivity (?90:10 for 13 examples) in catalyzing the formation of ?-lactones bearing two stereogenic centers from achiral aldehydes (both aromatic and aliphatic) and alkylarylketenes or dialkylketenes. A preference for formation of the trans diastereomer was observed in these reactions. For those reactions where BINAPHANE failed as a catalyst, tri-n-butylphosphine was found to be an effective achiral nucleophilic catalyst, effecting good yield and diastereoselectivity in racemic ?-lactone formation. Evidence for the involvement of phosphonium enolate intermediates in the reaction mechanism was obtained through reaction monitoring by (31)P NMR spectroscopy and by comparison with previously characterized intermediates observed in the phosphine-catalyzed ketene homodimerization reaction. PMID:24810117

Chen, Shi; Mondal, Mukulesh; Ibrahim, Ahmad A; Wheeler, Kraig A; Kerrigan, Nessan J

2014-06-01

179

Synthesis and characterization of aryl phosphine oxide containing thermoplastic polyimides and thermosetting polyimides with controlled reactivity  

NASA Astrophysics Data System (ADS)

Phosphorus containing monomers, bis(3-aminophenyl)methyl phosphine oxide (m-DAMPO) and bis(3-aminophenyl)phenyl phosphine oxide (m-DAPPO), were synthesized and incorporated into a thermoplastic poly(arylene ether imide) based upon 2,2sp'-bis (4-(3,4-dicarboxyphenoxy)phenyl) propane dianhydride and 1,3-phenylene diamine, in order to study their influence on flame resistance and other properties. DAMPO or DAPPO were quantitatively incorporated in concentrations of 25, 50, 75 and 100 mole percent, using the "one pot" ester-acid method. The number average molecular weights of the prepared materials were controlled to 20,000g/mol by off-setting the stoichiometry and endcapping with phthalic anhydride. This strategy enabled one to distinguish the effects of the phosphine oxide incorporation from the influence of molecular weight. The resulting copolymers demonstrated a significant increase in char yield as a function of the phosphine oxide content, thus suggesting improved fire resistance. Glass transition temperatures similar to the control were determined by DSC analysis. Analysis of the mechanical behavior of the DAMPO system at room temperature showed that tensile strength and elongation at failure values were comparable to the control system, while the DAPPO containing copolymers were surprisingly brittle. The influence of the reactive endgroup on the synthesis, cure behavior and network properties of thermosetting polyetherimides was investigated. Reactive phenylacetylene, acetylene and maleimide terminated poly(ether imide) oligomers were prepared and characterized. Optimal reaction conditions were established to produce fully endcapped oligomers with imidized structures and controlled molecular weight. The phenylacetylene endcapped system was synthesized by a conventional ester-acid method. The acetylene endcapped system was prepared via modified ester-acid method and the maleimide endcapped system was fabricated utilizing an amic-acid route. It was determined that phenylethynyl endcapped polymers could be thermally cured at high temperatures (350{-}380sp°C) providing good processibility. The networks exhibited thermal stability, chemical resistance and good adhesion strength, ideal as "primary" bonding adhesives. Acetylene and maleimide endcapped systems were prepared for application as "secondary" bonding materials, meaning that they are cured at a lower temperature than that of the Tg of the primary structure. Lap shear test results indicated good adhesion to titanium when cured at 250sp° C{-}280sp° C. The cured materials showed high glass transition temperatures and good thermal and thermo-oxidative stability as determined by DSC, TGA and DMA. Good chemical resistance was demonstrated via solvent extraction measurements. The influence of molecular weight between crosslinks (/line{M}sb{c}) on thermal and mechanical behavior was also investigated. Lower molecular weight oligomers exhibited lower Tg and cure temperatures, whereas the cured networks resulting from lower molecular weight oligomers afforded higher Tg and higher gel fractions, but reduced toughness.

Zhuang, Hong

1998-11-01

180

On the catalytic hydrodefluorination of fluoroaromatics using nickel complexes: the true role of the phosphine.  

PubMed

Homogeneous catalytic hydrodefluorination (HDF) of fluoroaromatics under thermal conditions was achieved using nickel(0) compounds of the type [(dippe)Ni(?(2)-C6F6-nHn)] where n = 0-2, as the catalytic precursors. These complexes were prepared in situ by reacting the compound [(dippe)Ni(?-H)]2 with the respective fluoroaromatic substrate. HDF seems to occur homogeneously, as tested by mercury drop experiments, producing the hydrodefluorinated products. However, despite previous findings by other groups, we found that these HDF reactions were actually the result of direct reaction of the alkylphosphine with the fluoroaromatic substrate. This metal- and silane-free system is the first reported example of a phosphine being able to hydrodefluorinate on its own. PMID:24432839

Arévalo, Alma; Tlahuext-Aca, Adrian; Flores-Alamo, Marcos; García, Juventino J

2014-03-26

181

Unprecedented hybrid scorpionate/phosphine ligand able to be anchored to carbosilane dendrimers.  

PubMed

The synthesis of a novel hybrid pyrazolate/phosphine anionic ligand [CH2=CHCH2B(CH2PPh2)(pz)2]- is described. Coordination of this ligand to metals in a fac tridentate fashion occurs in the complexes [CH2=CHCH2B(CH2PPh2)(pz)2M(cod)], prepared by reactions of the lithium salt of the ligand with [M(mu-Cl)(cod)]2 (M=Rh, Ir). They are pentacoordinated, with the rhodium complex showing a distorted trigonal-bipyramidal structure in the solid state, as determined by X-ray diffraction methods. Furthermore, the ligand has been linked to the periphery of a carbosilane dendrimer, resulting in the polyanionic dendrimer [Li(TMED)]4[Si{(CH2)3SiMe2(CH2)3B(CH2PPh2)(pz)2}4], which leads further to the corresponding metallodendrimer with four rhodium atoms. PMID:16323887

Casado, Miguel A; Hack, Verena; Camerano, José A; Ciriano, Miguel A; Tejel, Cristina; Oro, Luis A

2005-12-12

182

trans-Carbonyl-chloridobis(tri-p-tolyl-phosphine)rhodium(I) acetone solvate.  

PubMed

The title compound, [RhCl(C(21)H(21)P)(2)(CO)]·C(3)H(6)O, was precipitated in trace yield from a reaction of RhCl(cod)(THP) with P(p-tol)(3) in a 1:1 acetone-d(6)/CD(3)OD solution under a hydrogen atmosphere [p-tol = p-tolyl, THP = tris-(hydroxy-meth-yl)phosphine, P(CH(2)OH)(3), and cod = 1,5-cyclo-octa-diene]. The complex displays a square-planar geometry around the Rh(I) atom. The complex mol-ecules and the acetone mol-ecules are linked into a chain along the a axis by inter-molecular C-H?Cl and C-H?O hydrogen bonds. PMID:21201856

Lorenzini, Fabio; Patrick, Brian O; James, Brian R

2008-01-01

183

Water-soluble hydroxyalkylated phosphines: examples of their differing behaviour toward ruthenium and rhodium.  

PubMed

The reaction of P(CH2OH)3 (I) and P(C6H5)(CH2OH)2 (II) with RuCl3 in methanol eliminates two equivalents of formaldehyde to yield the mixed tertiary and secondary phosphine complexes all-trans-[RuCl2(P(CH2OH)3)2(P(CH2OH)2H)2] (1) and [RuCl2(P(C6H5)(CH2OH)2)2(P(C6H5)(CH2OH)H)2] (2), respectively. There is a high degree of hydrogen-bonding interactions between the hydroxymethyl groups in 1 and 2, although the phenyl groups of the latter reduce the extent of the network compared to 1. The generation of these mixed secondary and tertiary phosphine complexes is unprecedented. Under the same reaction conditions, the tris(hydroxypropyl)phosphine III formed no ruthenium complex. The reaction of P(CH2OH)3, P(C6H5)(CH2OH)2 and P{(CH2)3OH}3 with [RhCl(1,5-cod)]2 in an aqueous/dichloromethane biphasic medium yielded [RhH2(P(CH2OH)3)4]+ (3), [RhH2(P(C6H5)(CH2OH)2)4]+ (4) and [Rh(P(C6H5)(CH2OH)2)4]+ (5) and [Rh(P{(CH2)3OH}3)4]+ (6), respectively. Treating 5 with dihydrogen rapidly gave 4. The hydroxypropyl compound 6 formed the corresponding dihydride much more slowly in aqueous solution, although [RhH2(P{(CH2)3OH}3)4]+ (7) was readily formed by reaction with dihydrogen. Two separate reaction pathways are therefore involved; for P(CH2OH)3 and to a lesser extent P(C6H5)(CH2OH)2, the hydride source in the product is likely to be the aqueous solvent or the hydroxyl protons, whilst for P{(CH2)3OH}3 an oxidative addition of H2 is favoured. The protic nature of and was illustrated by the H-D exchange observed in d2-water. Dihydrides 3 and 4 reacted with carbon monoxide to yield the dicarbonyl cations [Rh(CO)2(P(CH2OH)3)3]+ (8) and [Rh(CO)2(P(C6H5)(CH2OH)2)3]+ (9). The analogous experiment with [RhH2(P{(CH2)3OH}3)4]+ resulted in phosphine exchange, although our experimental evidence points to the possibility of more than one fluxional process in solution. PMID:15573173

Higham, Lee J; Whittlesey, Michael K; Wood, Paul T

2004-12-21

184

Chiral phosphine-olefin ligands in the rhodium-catalyzed asymmetric 1,4-addition reactions.  

PubMed

A full overview on the use of chiral phosphine-olefin ligands 1 in the rhodium-catalyzed asymmetric 1,4-addition of arylboronic acids to alpha,beta-unsaturated carbonyl compounds is described. Effective chiral environment of a Rh/1 complex was shown to resemble that of a Rh/(R,R)-Ph-bod* complex by comparing the experimental results as well as the X-ray crystal structures. High catalytic activity of a Rh/1 complex was disclosed and the catalytic cycle involving a trimer-monomer equilibrium was established through mechanistic studies using a reaction calorimeter and (31)P NMR spectroscopy. A negative nonlinear effect derived from an inactive trimer-active monomer equilibrium of the catalyst was also successfully observed. PMID:17249670

Duan, Wei-Liang; Iwamura, Hiroshi; Shintani, Ryo; Hayashi, Tamio

2007-02-21

185

Novel Cyclic Phosphinic Acids as GABAC ? Receptor Antagonists: Design, Synthesis, and Pharmacology  

PubMed Central

Understanding the role of GABAC receptors in the central nervous system is limited due to a lack of specific ligands. Novel ?-aminobutyric acid (GABA) analogues based on 3-(aminomethyl)-1-oxo-1-hydroxy-phospholane 17 and 3-(guanido)-1-oxo-1-hydroxy-phospholane 19 were investigated to obtain selective GABAC receptor antagonists. A compound of high potency (19, KB = 10 ?M) and selectivity (greater than 100 times at ?1 GABAC receptors as compared to ?1?2?2L GABAA and GABAB(1b,2) receptors) was obtained. The cyclic phosphinic acids (17 and 19) are novel lead agents for developing into more potent and selective GABAC receptor antagonists with increased lipophilicity for future in vivo studies.

2010-01-01

186

Extraction of phenols from water with tri-octyl phosphine oxide  

SciTech Connect

Tri-octyl phosphine oxide (TOPO) was examined as an extractant for removing phenol; the dihydric phenols catechol, resorcinol, and hydroquinone; and the trihydric phenols pyrogallol, phloroglucinol, and 1,2,4-benzenetriol from water. Distribution coefficients were measured and results modelled for extractions with different diluents, solvent compositions, temperatures, and extractant-to-solute stoichiometric ratios. Modelling of the results indicates that the extraction mechanism is complicated, with the diluent probably playing an important role. The most effective diluents are those that have some electron-donating ability and are thus able to solvate the solute-TOPO complex, without competing with the solute for the phosphoryl oxygen on TOPO. The distribution coefficients decrease with increasing temperature, and show a linear dependence when plotted as ln(K/sub D/) vs. l/T.

MacGlashan, J.D.

1982-03-01

187

Rhodium–tris(3,5-bis(trifluoromethyl)phenyl)phosphine catalyzed hydroformylation of dienes to dialdehydes in supercritical carbon dioxide with high activity  

Microsoft Academic Search

Rhodium-catalyzed hydroformylation of 1,5-hexadiene and 1,7-octadiene to corresponding dialdehydes was investigated in compressed CO2 and in toluene using different fluorinated phosphine compounds as ligands. A rhodium complex using tris(3,5-bis(trifluoromethyl)phenyl)phosphine is highly effective in compressed CO2 for double hydroformylation of 1,5-hexadiene, whose TOF value is much larger than those reported so far. It has been shown that this ligand is effective

Shin-ichiro Fujita; Shinya Fujisawa; Bhalchandra M. Bhanage; Masahiko Arai

2004-01-01

188

Low-temperature phosphine fumigation of chilled lettuce under insulated cover for postharvest control of western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae)  

Microsoft Academic Search

Pallet-scale phosphine fumigations were conducted on pre-chilled iceberg lettuce under an insulated cover to determine efficacy against western flower thrips, Frankliniella occidentalis, and phytotoxicity to lettuce. Vacuum-cooled commercial iceberg lettuce at 3°C was sealed in a plastic bag, covered with double-bubble foil insulation, and then fumigated with 484±17ppm phosphine for 18h under storage at 20°C. Lettuce temperature increased from 4.5°C

Yong-Biao Liu

2011-01-01

189

Strong ligand field effects of blue phosphorescent Ir(III) complexes with phenylpyrazole and phosphines.  

PubMed

In the paper, we describe new Ir complexes for achieving efficient blue phosphorescence. New blue-emitting mixed-ligand Ir complexes comprising one cyclometalating, two phosphines trans to each other such as Ir(dppz)(PPh3)2(H)(L) (Ll= Cl, NCMe+, CN), [dppz = 3,5-Diphenylpyrazole] were synthesized and studied to tune the phosphorescence wavelength to the deep blue region and to enhance the luminescence efficiencies. To gain insight into the factors responsible for the emission color change and the variation of luminescence efficiency, we investigate the electron-withdrawing capabilities of ancillary ligands using DFT and TD-DFT calculations on the ground and excited states of the complexes. To achieve deep blue emission and increase the emission efficiency, (1) we substitute the phenyl group on the 3-position of the pyrazole ring that lowers the triplet energy enough that the quenching channel is not thermally accessible and (2) change the ancillary ligands coordinated to iridium atom to phosphine and cyano groups known as very strong field ligands. Their inclusion in the coordination sphere can increase the HOMO-LUMO gap to achieve the hypsochromic shift in emission color and lower the HOMO and LUMO energy level, which causes a large d-orbital energy splitting and avoids the quenching effect to improve the luminescence efficiency. The maximum emission spectra of Ir(dppz)(PPh3)2(H)(CI) and Ir(dppz)(PPh3)2(H)(CN) were in the ranges of 439, 432 nm, respectively. PMID:22849126

Park, Se Won; Ham, Ho Wan; Kim, Young Sik

2012-04-01

190

Axial-ligand substitution reactions of dirhodium(II) tetraacetate with phosphines and phosphites in acetonitrile  

SciTech Connect

The kinetic and thermodynamic parameters for the axial-ligand substitution reactions of the bis(acetonitrile) adduct of dirhodium(II) tetraacetate with a variety of phosphines and phosphites in acetonitrile have been measured. The rate-determining formation of the Rh/sub 2/(O/sub 2/CCH/sub 3/)/sub 4/(CH/sub 2/CN)PR/sub 3/ adduct occurs with a rate constant that is independent of the nature of the ligand: k/sub 1/(25.0/sup 0/C) = (1.05 +/- 0.05) x 10/sup 5/ M/sup -1/ s/sup -1/, ..delta..H/sub 1//sup ++/ = 10.9 +/- 0.6 kcal mol/sup -1/, and ..delta..S/sub 1//sup ++/ = 1 +/- 2 cal K/sup -1/ mol/sup -1/. Slightly higher rate constants (1.6 x 10/sup 5/ M/sup -1/ s/sup -1/ at 25.0/sup 0/C) were found for several diphosphines (PPh/sub 2/(CH/sub 2/)/sub n/PPh/sub 2/, n = 2-4) and are attributed to the presence of two ligand coordination sites. A dissociative mechanism is proposed for substitution of the axially coordinated acetonitrile, and the rate parameters are compared with values reported for substitutions of oxygen-donor solvent molecules on the dirhodium(II) complex. The stability constants for the mono- and bisadducts have been measured at 25/sup 0/C with K/sub 1//K/sub 2/ approx. 20. The dependence of K/sub 1/ and K/sub 2/ on the nature of the phosphine or phosphite correlates well with the sigma-donor strength of the ligand, with ..pi..-acceptor strengths and steric effects being relatively insignificant.

Aquino, M.A.S.; Macartney, D.H.

1987-08-12

191

Phosphinic Acid functionalized polyazacycloalkane chelators for radiodiagnostics and radiotherapeutics: unique characteristics and applications.  

PubMed

Given the wide application of positron emission tomography (PET), positron-emitting metal radionuclides have received much attention recently. Of these, gallium-68 has become particularly popular, as it is the only PET nuclide commercially available from radionuclide generators, therefore allowing local production of PET radiotracers independent of an on-site cyclotron. Hence, interest in optimized bifunctional chelators for the elaboration of (68) Ga-labeled bioconjugates has been rekindled as well, resulting in the development of improved triazacyclononane-triphosphinate (TRAP) ligand structures. The most remarkable features of these ligands are unparalleled selectivity for Ga(III) , rapid Ga(III) complexation kinetics, extraordinarily high thermodynamic stability, and kinetic inertness of the respective Ga(III) chelates. As a result, TRAP chelators exhibit very favorable (68) Ga-labeling properties. Based on the scaffolds NOPO (1,4,7-triazacyclononane-1,4-bis[methylene(hydroxymethyl)phosphinic acid]-7-[methylene(2-carboxyethyl)phosphinic acid]) and TRAP-Pr, tailored for convenient preparation of (68) Ga-labeled monomeric and multimeric bioconjugates, a variety of novel (68) Ga radiopharmaceuticals have been synthesized. These include bisphosphonates, somatostatin receptor ligands, prostate-specific membrane antigen (PSMA)-targeting peptides, and cyclic RGD pentapeptides, for in vivo PET imaging of bone, neuroendocrine tumors, prostate cancer, and integrin expression, respectively. Furthermore, TRAP-based (68) Ga-labeled gadolinium(III) complexes have been proposed as bimodal probes for PET/MRI, and a cyclen-based analogue of TRAP-Pr has been suggested for the elaboration of targeted radiotherapeutics comprising radiolanthanide ions. Thus, polyazacycloalkane-based polyphosphinic acid chelators are a powerful toolbox for pharmaceutical research, particularly for the development of (68) Ga radiopharmaceuticals. PMID:24700633

Notni, Johannes; Sime?ek, Jakub; Wester, Hans-Jürgen

2014-06-01

192

Sterically crowded peri-substituted naphthalene phosphines and their PV derivatives.  

PubMed

Three sterically crowded peri-substituted naphthalene phosphines, Nap[PPh(2)][ER] (Nap=naphthalene-1,8-diyl; ER=SEt, SPh, SePh) 1-3, which contain phosphorus and chalcogen functional groups at the peri positions have been prepared. Each phosphine reacts to form a complete series of P(V) chalcogenides Nap[P(E')(Ph(2))(ER)] (E'=O, S, Se). The novel compounds were fully characterised by using X-ray crystallography and multinuclear NMR spectroscopy, IR spectroscopy and MS. X-ray data for 1, 2, nO, nS, nSe (n=1-3) are compared. Eleven molecular structures have been analysed by naphthalene ring torsions, peri-atom displacement, splay angle magnitude, X...E interactions, aromatic ring orientations and quasi-linear arrangements. An increase in the congestion of the peri region following the introduction of heavy chalcogen atoms is accompanied by a general increase in naphthalene distortion. P...E distances increase for molecules that contain bulkier atoms at the peri positions and also when larger chalcogen atoms are bound to phosphorus. The chalcogenides adopt similar conformations that contain a quasi-linear E...P-C fragment, except for 3O, which displays a twist-axial-twist conformation resulting in the formation of a linear O...Se-C alignment. Ab initio MO calculations performed on 2O, 3O, 3S and 3Se reveal Wiberg bond index values of 0.02 to 0.04, which indicates only minor non-bonded interactions; however, calculations on radical cations of 3O, 3S and 3Se reveal increased values (0.14-0.19). PMID:20496359

Knight, Fergus R; Fuller, Amy L; Bühl, Michael; Slawin, Alexandra M Z; Woollins, J Derek

2010-07-01

193

Activation of tri(2-furyl)phosphine at a dirhenium centre: Formation of phosphido-bridged dirhenium complexes  

Microsoft Academic Search

Reaction of tri(2-furyl)phosphine (PFu3) with [Re2(CO)10?n(NCMe)n] (n=1, 2) at 40°C gave the substituted complexes [Re2(CO)10?n(PFu3)n] (1 and 2), the phosphines occupying axial position in all cases. Heating [Re2(CO)10] and PFu3 in refluxing xylene also gives 1 and 2 together with four phosphido-bridged complexes; [Re2(CO)8?n(PFu3)n(?-PFu2)(?-H)] (n=0, 1, 2) (3–5) and [Re2(CO)6(PFu3)2(?-PFu2)(?-Cl)] (6) resulting from phosphorus–carbon bond cleavage. A series of separate

Shishir Ghosh; Mansura Khatun; Daniel T. Haworth; Sergey V. Lindeman; Tasneem A. Siddiquee; Dennis W. Bennett; Graeme Hogarth; Ebbe Nordlander; Shariff E. Kabir

2009-01-01

194

Investigation of the surface chemistry of phosphine-stabilized ruthenium nanoparticles--an advanced solid-state NMR study.  

PubMed

(31)P-(13)C REDOR NMR measurements allowed a reasonable approximation of distances between stabilizing ligands and carbon monoxide (CO) molecules on the surface of phosphine-stabilized ruthenium nanoparticles (RuNPs). The studied systems are RuNPs in the size range of 1-2 nm stabilized with 1,3,5-triaza-7-phosphaadamantane (PTA) or triphenylphosphine (PPh3) and exposed to a CO atmosphere. This study sheds some light on the interactions between CO and phosphine molecules as well as on their binding geometries on the surface of the RuNPs. As information on the ligand location and mobility is precious for the understanding of the chemical and catalytic properties of nanoparticles, these results support the interest of using sophisticated NMR tools to investigate their surface chemistry. PMID:24022656

Gutmann, Torsten; Bonnefille, Eric; Breitzke, Hergen; Debouttière, Pierre-Jean; Philippot, Karine; Poteau, Romuald; Buntkowsky, Gerd; Chaudret, Bruno

2013-10-28

195

Remote plasma enhanced chemical vapor deposition of GaP with in situ generation of phosphine precursors  

NASA Technical Reports Server (NTRS)

Thin homoepitaxial films of gallium phosphide (GaP) were grown by remote plasma enhanced chemical vapor deposition utilizing in situ generated phosphine precursors. The GaP forming reaction is kinetically controlled with an activation energy of 0.65 eV. The increase of the growth rate with increasing radio frequency (rf) power between 20 and 100 W is due to the combined effects of increasingly complete excitation and the spatial extension of the glow discharge toward the substrate, however, the saturation of the growth rate at even higher rf power indicates the saturation of the generation rate of phosphine precursors at this condition. Slight interdiffusion of P into Si and Si into GaP is indicated from GaP/Si heterostructures grown under similar conditions as the GaP homojunctions.

Choi, S. W.; Lucovsky, G.; Bachmann, Klaus J.

1993-01-01

196

Remote plasma enhanced chemical vapor deposition of GaP with in situ generation of phosphine precursors  

NASA Technical Reports Server (NTRS)

Thin homoepitaxial films of gallium phosphide (GaP) have been grown by remote plasma enhanced chemical vapor deposition utilizing in situ-generated phosphine precursors. The GaP forming reaction is kinetically controlled with an activation energy of 0.65 eV. The increase of the growth rate with increasing radio frequency (RF) power between 20 and 100 W is due to the combined effects of increasingly complete excitation and the spatial extension of the glow discharge toward the substrate; however, the saturation of the growth rate at even higher RF power indicates the saturation of the generation rate of phosphine precursors at this condition. Slight interdiffusion of P into Si and Si into GaP is indicated from GaP/Si heterostructures grown under similar conditions as the GaP homojunctions.

Choi, S. W.; Lucovsky, G.; Bachmann, K. J.

1992-01-01

197

In vitro and in vivo characterization of a 99mTc complex with tris(hydroxymethyl)phosphine (THP)  

Microsoft Academic Search

The water-soluble, monophosphine ligand tris(hydroxymethyl)phosphine (THMP) was complexed with 99mTc. The 99mTc-THMP was formed in high radiochemical purity by simply mixing 99mTcO4? with THMP over a wide pH range. In vitro and in vivo studies indicated the complex to be highly stable under the respective conditions. HPLC analysis indicated a singular species with a retention time identical to the known

D. E. Berning; K. V. Katti; P. R. Singh; C. Higgenbotham; V. Sreenivasa Reddy; W. A. Volkert

1996-01-01

198

Asymmetric catalysis of Morita-Baylis-Hillman reactions by chiral phosphine Lewis bases bearing multiple phenol groups.  

PubMed

In the Morita-Baylis-Hillman (MBH) reactions of arylaldehydes with methyl vinyl ketone, it was observed that in the presence of a catalytic amount of a chiral phosphine Lewis base (CPLB) bearing multiple phenol groups, such as CPLB1 (10 mol %), the corresponding MBH adducts could be obtained in moderate to good yields with low to moderate ee's (4-45% ee) at ambient temperature (10 degrees C) in THF. PMID:17117401

Shi, Min; Liu, Ying-Hao; Chen, Lian-Hui

2007-02-01

199

Phosphine-free synthesis of p-type copper(I) selenide nanocrystals in hot coordinating solvents.  

PubMed

We report a phosphine-free synthesis of p-type copper(I) selenide nanocrystals by a colloidal approach in a mixture of oleylamine and 1-octadecene. The nanocrystals had a cuboctahedral shape and cubic berzelianite phase. Films of these nonstoichiometric copper-deficient Cu(2-x)Se nanocrystals were highly conductive and showed high absorption coefficient in the near-infrared region. These nanocrystals could be used as hole-injection layers in optoelectronic devices. PMID:20540521

Deka, Sasanka; Genovese, Alessandro; Zhang, Yang; Miszta, Karol; Bertoni, Giovanni; Krahne, Roman; Giannini, Cinzia; Manna, Liberato

2010-07-01

200

Synthesis and microwave spectrum of (2-chloroethyl)phosphine (ClCH(2)CH(2)PH(2)).  

PubMed

The synthesis of a 2-halogenoethylphosphine, (2-chloroethyl)phosphine (ClCH(2)CH(2)PH(2)), is reported for the first time. This compound was prepared by a chemoselective reduction of diethylchloroethylphosphonate with dichloroalane using a vacuum line. (2-Chloroethyl)phosphine has been studied by microwave spectroscopy at room temperature, or at -20 degrees C, in the 22-80 GHz spectral interval. The experimental study has been augmented by quantum chemical calculations at the MP2/6-311++(3df,3pd) and B3LYP/6-311++(3df,3pd) levels of theory. The spectra of two rotameric forms, denoted I and II have been assigned. These conformers both have an antiperiplanar arrangement for the Cl-C-C-P chain of atoms, but with different orientation of the phosphine group. Conformer I was found to be 5.2(6) kJ/mol more stable than II by relative intensity measurements. The spectra of the first excited states of the C-C torsional vibration of both I and II were assigned. The torsional frequency was determined to be 63(20) cm(-1) for conformer I by relative intensity measurements, and it has a similar value in II. It was found that this normal vibration deviates from a near-harmonic behavior. The quantum chemical calculations produce rotational and centrifugal distortion constants that are in satisfactory agreement with observations, but fail to predict correctly low-frequency fundamental frequencies. The quantum chemical calculations indicate that three additional conformers characterized by a synclinal orientation for the Cl-C-C-P link of atoms and with different orientation of the phosphine group are high-energy forms of ClCH(2)CH(2)PH(2). Searches for these forms were unsuccessful. PMID:19905017

Møllendal, Harald; Konovalov, Alexey; Guillemin, Jean-Claude

2009-11-19

201

Phosphine-catalyzed intramolecular ?-umpolung addition of ?-aminoalkylallenic esters: facile synthesis of 3-carbethoxy-2-alkyl-3-pyrrolines.  

PubMed

An array of N-tosylated ?-aminoalkylallenic esters was prepared and their cyclization under the influence of nucleophilic phosphine catalysts was explored. The ?-aminoalkylallenic esters were prepared through aza-Baylis-Hillman reactions or novel DABCO-mediated decarboxylative rearrangements of allenylic carbamates. Conversion of these substrates to 3-carbethoxy-2-alkyl-3-pyrrolines was facilitated through Ph(3)P-catalyzed intramolecular ?-umpolung addition. PMID:22526463

Andrews, Ian P; Blank, Brian R; Kwon, Ohyun

2012-05-28

202

Studies on the use of octyl (phenyl) phosphinic acid (OPPA) for extraction of yttrium (III) from chloride medium  

Microsoft Academic Search

Extraction behaviour of Y(III) from hydrochloric acid medium by octyl phenyl phosphinic acid (OPPA) has been investigated over a wide range of experimental conditions such as feed acidity, yttrium concentration, OPPA concentration, diluents, temperature, stripping reagents. The extraction mechanism of Y(III) with OPPA was established using distribution data obtained by slope analysis technique and it showed the formation of Y(HA2)3

Mallavarapu Anitha; Dhruva Kumar Singh; Ritesh Ruhela; Jyotinath Sharma; Harvinderpal Singh

2012-01-01

203

Phosphine-catalyzed [3 + 2] cycloaddition of sulfamate-derived cyclic imines with allenoate: synthesis of sulfamate-fused dihydropyrroles.  

PubMed

Ph3P-catalyzed [3 + 2] cycloaddition reaction of sulfamate-derived cyclic imines with allenoate has been developed, affording sulfamate-fused dihydropyrroles under very mild conditions in high yields. Using amino acid-based bifunctional phosphine as chiral catalyst, its asymmetric variant provided the corresponding products in good yields with moderate to excellent enantiomeric excesses (up to 91% yield and up to 98% ee). Subsequent transformations of the heterocyclic products gave various pharmaceutically attractive compounds. PMID:23895382

Yu, Hao; Zhang, Lei; Yang, Zhilin; Li, Zhen; Zhao, Yan; Xiao, Yumei; Guo, Hongchao

2013-09-01

204

Homogeneous hydrogenation of norbornadiene with parahydrogen and phosphonic ester phosphine rhodium complexes studied by in situ nmr spectroscopy  

Microsoft Academic Search

1) Homogeneous hydrogenation of norbornadiene with enriched parahydrogen (p-H2) and phosphonic ester phosphine rhodium complexes is detected using in situ NMR spectroscopy The obtained polarization spectra remain unchanged during the catalysis in thf-d8 as a solvent but change with time when the hydrogenation is executed in acetone-d6. 2) The observed phenomenon is attributed to a change of the phase correlation

A Weigt; K WOELK; J BARGON

1995-01-01

205

Phosphines with 2-imidazolium ligands enhance the catalytic activity and selectivity of rhodium complexes for hydrosilylation reactions  

Microsoft Academic Search

Phosphines with 2-imidazolium ligands can specifically vary their physical and chemical properties by altering the attached substituents. Rhodium complexes (1b–7b) exhibited excellent catalytic activity and selectivity for hydrosilylation of olefins. The selectivity of the ?-adduct clearly increased when the length of the alkyl chain bound to the imidazolium cation increased. Rhodium complex 1b in BMimPF6 can be reused without noticeable

Jiayun Li; Jiajian Peng; Ying Bai; Guodong Zhang; Guoqiao Lai; Xiaonian Li

2010-01-01

206

Novel axially chiral phosphine ligand with a fluoro alcohol moiety for Rh-catalyzed asymmetric arylation of aromatic aldehydes.  

PubMed

A new chiral phosphine ligand (R)-1 possessing a fluoroalcohol moiety was prepared. The (R)-1-coordinated Rh(I) complex showed an excellent catalytic activity for asymmetric 1,2-addition of arylboronic acids to aldehydes to afford highly enantioenriched diarylmethanols. The fluoroalcohol moiety in ligand (R)-1 plays a pivotal role for the high enantioselectivity of the present Rh(I)-catalyzed transformation. PMID:20462207

Morikawa, Satoshi; Michigami, Kyosuke; Amii, Hideki

2010-06-01

207

Recovery of plutonium from nitric acid containing oxalate and fluoride by a macroporous bifunctional phosphinic acid resin (MPBPA)  

Microsoft Academic Search

Summary  The sorption of Pu from nitric acid solutions containing oxalate\\/fluoride was studied using an indigenously available macroporous\\u000a bifunctional phosphinic acid (MPBPA) resin. Batch experiments were carried out to obtain the distribution data of Pu(IV) with\\u000a a view to optimize conditions for its recovery from nitric acid waste solutions containing oxalate or fluoride ions. The measurements\\u000a showed high distribution ratio (D)

K. Venugopal Chetty; A. G. Godbole; R. Swarup; V. N. Vaidya; V. Venugopal; P. R. Vasudeva Rao

2005-01-01

208

Differences between amine- and phosphine-boranes: synthesis, photoelectron spectroscopy, and quantum chemical study of the cyclopropylic derivatives.  

PubMed

Borane complexes of aziridine, phosphirane, cyclopropylamine, cyclopropylphosphine, cyclopropylmethylamine, and cyclopropylmethylphosphine have been prepared by the reaction at low temperatures of a borane complex or diborane on the free phosphine or amine. The products characterized by NMR spectroscopy and mass spectrometry have then been investigated by photoelectron spectroscopy and B3LYP/aug-cc-pVTZ quantum chemical study. The complexation led to rotamers with structures similar to the ones of the corresponding free systems. The main geometry change with the complexation is the P-C bond elongation and the N-C bond shortening, which can be rationalized by the charge transfer attached to the electron donation. The calculated relative stability order of the conformers changes with the complexation only in the case of cyclopropylamine. The calculated complexation energies are higher for the amines, in accord with the differences observed in the flash vacuum thermolysis of methylamine-, methylphosphine-, and aziridine-borane. The photoelectron spectra indicate essential differences between the amines and phosphines toward borane complexation. The dative bond is more stable in the studied amine-boranes than in phosphine-boranes, while the sigma(B-H) orbitals are more stable in the latter compounds. The enthalpy of the hydrogen release reaction of aziridine-borane is almost thermoneutral, indicating the potential of this complex as recyclable hydrogen storage material. PMID:20433190

Németh, Balázs; Khater, Brahim; Guillemin, Jean-Claude; Veszprémi, Tamás

2010-06-01

209

The rph2 gene is responsible for high level resistance to phosphine in independent field strains of Rhyzopertha dominica.  

PubMed

The lesser grain borer Rhyzopertha dominica (F.) is one of the most destructive insect pests of stored grain. This pest has been controlled successfully by fumigation with phosphine for the last several decades, though strong resistance to phosphine in many countries has raised concern about the long term usefulness of this control method. Previous genetic analysis of strongly resistant (SR) R. dominica from three widely geographically dispersed regions of Australia, Queensland (SR(QLD)), New South Wales (SR(NSW)) and South Australia (SR(SA)), revealed a resistance allele in the rph1 gene in all three strains. The present study confirms that the rph1 gene contributes to resistance in a fourth strongly resistant strain, SR2(QLD), also from Queensland. The previously described rph2 gene, which interacts synergistically with rph1 gene, confers strong resistance on SR(QLD) and SR(NSW). We now provide strong circumstantial evidence that weak alleles of rph2, together with rph1, contribute to the strong resistance phenotypes of SR(SA) and SR2(QLD). To test the notion that rph1 and rph2 are solely responsible for the strong resistance phenotype of all resistant R. dominica, we created a strain derived by hybridising the four strongly resistant lines. Following repeated selection for survival at extreme rates of phosphine exposure, we found only slightly enhanced resistance. This suggests that a single sequence of genetic changes was responsible for the development of resistance in these insects. PMID:22461899

Mau, Yosep S; Collins, Patrick J; Daglish, Gregory J; Nayak, Manoj K; Ebert, Paul R

2012-01-01

210

Theory-Guided Design of Br?nsted Acid-Assisted Phosphine Catalysis: Synthesis of Dihydropyrones from Aldehydes and Allenoates  

PubMed Central

The phosphine-catalyzed addition of 2,3-butadienoates to aldehydes has been extended to the formation of disubstituted dihydro-2-pyrones. The requisite shift in equilibrium of the intermediate zwitterionic ?-phosphonium dienolates toward the s-cis intermediate was accomplished through the use of a Brønsted acid additive, which disrupts the favorable Coulombic interaction present in the s-trans intermediate. The detailed nature of the synergistic interactions involving the Brønsted acid additives and phosphine involved in the formation of s-cis ?-phosphonium dienolates was analyzed through a series of DFT calculations. Unlike previously reported annulations of aldehydes with allenoates, where trialkylphosphines are optimal catalysts, in this study triphenylphosphine was also found for the first time to be a suitable catalyst for the synthesis of dihydropyrones. This method provides a one-step route toward functionalized dihydropyrones from simple, stable starting materials. In addition, new reaction pathways of phosphine-catalyzed allene annulations are unveiled, with the formation of dihydropyrones being the first example of dual activation in this sphere.

Creech, Gardner S.; Zhu, Xue-Feng; Fonovic, Branden; Dudding, Travis; Kwon, Ohyun

2008-01-01

211

Intramolecular alkyl phosphine dehydrogenation in cationic rhodium complexes of tris(cyclopentylphosphine).  

PubMed

[Rh(nbd)(PCyp(3))(2)][BAr(F) (4)] (1) [nbd = norbornadiene, Ar(F) = C(6)H(3)(CF(3))(2), PCyp(3) = tris(cyclopentylphosphine)] spontaneously undergoes dehydrogenation of each PCyp(3) ligand in CH(2)Cl(2) solution to form an equilibrium mixture of cis-[Rh{PCyp(2)(eta(2)-C(5)H(7))}(2)][BAr(F) (4)] (2 a) and trans-[Rh{PCyp(2)(eta(2)-C(5)H(7))}(2)][BAr(F) (4)] (2 b), which have hybrid phosphine-alkene ligands. In this reaction nbd acts as a sequential acceptor of hydrogen to eventually give norbornane. Complex 2 b is distorted in the solid-state away from square planar. DFT calculations have been used to rationalise this distortion. Addition of H(2) to 2 a/b hydrogenates the phosphine-alkene ligand and forms the bisdihydrogen/dihydride complex [Rh(PCyp(3))(2)(H)(2)(eta(2)-H(2))(2)][BAr(F) (4)] (5) which has been identified spectroscopically. Addition of the hydrogen acceptor tert-butylethene (tbe) to 5 eventually regenerates 2 a/b, passing through an intermediate which has undergone dehydrogenation of only one PCyp(3) ligand, which can be trapped by addition of MeCN to form trans-[Rh{PCyp(2)(eta(2)-C(5)H(7))}(PCyp(3))(NCMe)][BAr(F) (4)] (6). Dehydrogenation of a PCyp(3) ligand also occurs on addition of Na[BAr(F) (4)] to [RhCl(nbd)(PCyp(3))] in presence of arene (benzene, fluorobenzene) to give [Rh(eta(6)-C(6)H(5)X){PCyp(2)(eta(2)-C(5)H(7))}][BAr(F) (4)] (7: X = F, 8: X = H). The related complex [Rh(nbd){PCyp(2)(eta(2)-C(5)H(7))}][BAr(F) (4)] 9 is also reported. Rapid ( approximately 5 minutes) acceptorless dehydrogenation occurs on treatment of [RhCl(dppe)(PCyp(3))] with Na[BAr(F) (4)] to give [Rh(dppe){PCyp(2)(eta(2)-C(5)H(7))}][BAr(F) (4)] (10), which reacts with H(2) to afford the dihydride/dihydrogen complex [Rh(dppe)(PCyp(3))(H)(2)(eta(2)-H(2))][BAr(F) (4)] (11). Competition experiments using the new mixed alkyl phosphine ligand PCy(2)(Cyp) show that [RhCl(nbd){PCy(2)(Cyp)}] undergoes dehydrogenation exclusively at the cyclopentyl group to give [Rh(eta(6)-C(6)H(5)X){PCy(2)(eta(2)-C(5)H(7))}][BAr(F) (4)] (17: X = F, 18: X = H). The underlying reasons behind this preference have been probed using DFT calculations. All the complexes have been characterised by multinuclear NMR spectroscopy, and for 2 a/b, 4, 6, 7, 8, 9 and 17 also by single crystal X-ray diffraction. PMID:17992682

Douglas, Thomas M; Brayshaw, Simon K; Dallanegra, Romaeo; Kociok-Köhn, Gabriele; Macgregor, Stuart A; Moxham, Gemma L; Weller, Andrew S; Wondimagegn, Tebikie; Vadivelu, Prabha

2008-01-01

212

Accessible gold clusters using calix[4]arene N-heterocyclic carbene and phosphine ligands.  

PubMed

We investigate the synthesis of accessible calix[4]arene-bound gold clusters consisting of open "coordinatively unsaturated" active sites, using a comparative approach that relies on calix[4]arene ligands with various upper- and lower-rim substituents. In contrast with a reported Au(I)-tert-butyl-calixarene phosphine complex, which exhibits a single cone conformer in solution, the H upper-rim analog exhibits multiple conformers in solution. This contrasts with observations of the tert-butyl upper-rim analog, which exhibits a single cone conformer in solution under similar conditions. In the solid state, as determined by single-crystal X-ray diffraction, both H and tert-butyl upper-rim analogs exhibit exclusively cone conformer. A detailed structural analysis of these two solid-state structures highlights a CH-? interaction involving a methoxy lower-rim substituent and phenyl substituent on P as the key feature that enforces a tight configuration of Au(I) atoms on the same side of the calix[4]arene lower-rim plane. We hypothesize that such a configuration promotes chelation of the ligand to a gold surface and facilitates the synthesis of small Au11-sized clusters after reduction of both complexes. The new cluster, like the one reported with the tert-butyl analog, has an extraordinary 25% of surface atoms that are open and accessible to a 2-NT (2-naphthalenethiol) probe in solution. We also investigated the effect of calix[4]arene lower-rim substituents that coordinate to the metal, by using N-heterocyclic carbene (NHC) functional groups rather than phosphines. Four small (<1.6 nm diameter) calix[4]arene NHC-bound gold clusters were synthesized, including three using novel calix[4]arene NHC ligands. The smallest calix[4]arene NHC-bound Au cluster consisted of a 1.2 nm gold core, and its number density of accessible and open surface sites was measured. This required development of a new titration method for open sites on gold clusters, using a SAMSA fluorescein dye molecule, which excites and emits at lower energy relative to the previously used 2-NT probe. The number density of open sites on the new calix[4]arene NHC-bound gold cluster measured by the SAMSA fluorescein probe strongly supports the generality of a mechanical model of accessibility, which does not depend on the functional group involved in binding to the gold surface and rather depends on the relative radii of curvature of bound ligands and the gold cluster core. PMID:23917776

Nigra, Michael M; Yeh, Alexander J; Okrut, Alexander; DiPasquale, Antonio G; Yeh, Sheila W; Solovyov, Andrew; Katz, Alexander

2013-09-21

213

Palladium-catalyzed Suzuki-Miyaura cross-coupling reactions employing dialkylbiaryl phosphine ligands.  

PubMed

The cores of many types of polymers, ligands, natural products, and pharmaceuticals contain biaryl or substituted aromatic structures, and efficient methods of synthesizing these structures are crucial to the work of a broad spectrum of organic chemists. Recently, Pd-catalyzed carbon-carbon bond-forming processes, particularly the Suzuki-Miyaura cross-coupling reaction (SMC), have risen in popularity for this purpose. The SMC has many advantages over other methods for constructing these moieties, including mild conditions, high tolerance toward functional groups, the commercial availability and stability of its reagents, and the ease of handling and separating byproducts from its reaction mixtures. Until 1998, most catalysts for the SMC employed triarylphosphine ligands. More recently, new bulky and electron-rich phosphine ligands, which can dramatically improve the efficiency and selectivity of such cross-coupling reactions, have been introduced. In the course of our studies on carbon-nitrogen bond-forming reactions, we found that the use of electron-rich and bulky phosphines enhanced the rate of both the oxidative addition and reductive elimination processes; this was the beginning of our development of a new family of ligands, the dialkylbiarylphosphines L1-L12. These ligands can be used for a wide variety of palladium-catalyzed carbon-carbon, carbon-nitrogen, and carbon-oxygen bond-forming processes as well as serving as supporting ligands for a number of other reactions. The enhanced reactivity of these catalysts has expanded the scope of cross-coupling partners that can be employed in the SMC. With use of such dialkylbiarylphosphine ligands, the coupling of unactivated aryl chlorides, aryl tosylates, heteroaryl systems, and very hindered substrate combinations have become routine. The utility of these ligands has been successfully demonstrated in a wide number of synthetic applications, including industrially relevant processes. In this Account, we provide an overview of the use and impact of dialkylbiarylphosphine ligands in the SMC. We discuss our studies on the mechanistic framework of the reaction, which have allowed us to rationally modify the ligand structures in order to tune their properties. We also describe selected applications in the synthesis of natural products and new materials to illustrate the utility of these dialkylbiarylphosphine ligands in various "real-world" synthetic applications. PMID:18620434

Martin, Ruben; Buchwald, Stephen L

2008-11-18

214

The complexes: RhCl(P–N)(THP), where P–N is P, N-chelated o-diphenylphosphino- N, N-dimethylaniline and THP is tris(hydroxymethyl)phosphine, and RhCl[(O)P–N][THP(O)] containing O-bonded phosphine oxides  

Microsoft Academic Search

The complex RhCl(P–N)(THP) (1) is synthesized under argon from RhCl(cod)(THP) and P–N, and is structurally characterized; P–N=P,N-chelated o-diphenylphosphino-N,N-dimethylaniline, THP=tris(hydroxymethyl)phosphine, and cod=1,5-cyclo-octadiene. The corresponding synthesis in air yields RhCl[(O)P–N][THP(O)] (2), containing O-bonded phosphine oxide ligands.

Fabio Lorenzini; Brian O. Patrick; Brian R. James

2008-01-01

215

Global Modeling of Phosphine (PH3) Spectra: 13 to 2.8 ?m  

NASA Astrophysics Data System (ADS)

In order to support remote sensing of Saturn and Jupiter, the infrared spectrum of PH3 was studied using high resolution (R>360000) laboratory spectra obtained with Fourier transform spectrometers. The line positions and intensities involving up to 21 sub-vibrational states were analyzed simultaneously using theoretical models developed in France and extended in Russia. The polyads considered were the Dyad (13 - 7.3 ?m), Pentad (5.9 - 3.8 ?m) and Octad (3.7 - 3.1 ?m). The improved quantum mechanical models were implemented using an effective Hamiltonian in the form of irreducible tensors. The global modeling permitted more extensive quantum assignments to be made for transitions arising from both from the ground state and the two lowest fundamentals. The standard deviations of the global fit represent significant improvement with respect to previous studies of phosphine spectroscopy at these wavelengths. These results will be presented. Part of the research described in this paper was performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with The National Aeronautics and Space Administration. I.K. also thanks the Programme National de Planétologie for funding part of this research.

Brown, Linda R.; Nikitin, A.; Champion, J.; Kleiner, I.; Butler, R. A. H.

2008-09-01

216

Short-axis substitution approach selectively optimizes electrical properties of dibenzothiophene-based phosphine oxide hosts.  

PubMed

Two dibenzothiophene (DBT)-based phosphine oxide hosts, named 4-diphenylphosphoryl dibenzothiophene (DBTSPO) and 4,6-bis(diphenylphosphoryl) dibenzothiophene (DBTDPO), were prepared by short-axis substitution with the aim to selectively adjust electrical properties. The combined effects of short-axis substitution and the involvement of electron-donating S atom in conjugation effectively suppress the influence of electron-withdrawing diphenylphosphine oxide (DPPO) moieties on the frontier molecular orbitals and the optical properties. Therefore, DBTSPO and DBTDPO have the nearly same hole injection ability and the excited energy levels, while more electron-transporting DPPOs and the symmetrical configuration endow DBTDPO with enhanced electron-injecting/transporting ability. As the result, on the basis of this short-axis substitution effect, the selective adjustment of electrical properties was successfully realized. With the high first triplet energy level (T(1)) of 2.90 eV, the suitable energy levels of the highest occupied molecular orbital and the lowest unoccupied molecular orbital of -6.05 and -2.50 eV and the improved carrier-transporting ability, DBTDPO supported its blue- and white-emitting phosphorescent organic light-emitting diodes as the best low-voltage-driving devices reported so far with the lowest driving voltages of 2.4 V for onset and <3.2 V at 1000 cd m(-2) (for indoor lighting) accompanied with the high efficiencies of >30 lm W(-1) and excellent efficiency stability. PMID:23106383

Han, Chunmiao; Zhang, Zhensong; Xu, Hui; Yue, Shouzhen; Li, Jing; Yan, Pingrui; Deng, Zhaopeng; Zhao, Yi; Yan, Pengfei; Liu, Shiyong

2012-11-21

217

Photolysis of phosphine in the presence of acetylene and propyne, gas mixtures of planetary interest.  

PubMed

Phosphine (PH3) 1 has been observed in the atmospheres of Jupiter and Saturn. We have studied the photochemical reactions of this compound with acetylene (C2H2), an alkyne also detected in these atmospheres. The volatile products formed in these reactions were characterized by H, 31P and 13C NMR. The ethenylphosphine 2 is the first product formed in the photolysis of PH3 in the presence Of C2H2. Photolysis of PH3 in the presence of propyne (C3H4) led to the formation of the Z- and E-prop-1-enylphosphines and traces of 1-methylethenylphosphine. A reaction pathway is proposed. The initial step is the dissociation of PH3 to hydrogen and PH2 radicals. Addition of the phosphinyl radical on alkyne occurs as the next step. Vinylphosphines are then formed by radical combination. This proposed reaction pathway takes into account the nature of the products and studies devoted to the photolysis of germane (GeH4) or hydrogen sulfide (H2S) in the presence of alkyne. Attempts to detect the methylidynephosphine HC triple bond P (the isoelectronic compound of HC triple bond N), in the photolysis products of PH3-C2H2 mixtures were unsuccessful. The application of these findings to Jovian and Saturn atmospheric chemistry is discussed. PMID:11543539

Guillemin, J C; Janati, T; Lassalle, L

1995-01-01

218

Photophysics of Mixed Ligand Complexes of Ruthenium(II) with 2,2'-bipyridyl and Phosphines  

NASA Astrophysics Data System (ADS)

Luminescence of mixed ligand complexes of ruthenium(II) of the types cis-Ru(bpy)2X2( I), cis-[Ru(bpy)2(PPh3)X](BF4)( II), and cis-Ru(bpy)(PP)X2( III) (X = CN, NO2, PPh3 is triphenyl phosphine; PP is 1,2-bis(diphenylphospino)ethane (dppe) and cis-,2-bis(diphenylphosphino)ethylene (dppene)) is studied in alcohol matrices (EtOH/MeOH, 4:1) frozen at 77 K. A sequence of complexes I-III exhibits an additive (in the number of phosphorous atoms) blue shift of the absorption and luminescence bands and an increase in the quantum yield of luminescence and in the excited-state lifetime. The rate constant of nonradiative deactivation of the excited state decreases more than by an order of magnitude in the sequence I-III of cyano complexes and only by three times in a sequence of nitro complexes. This is assumed to be caused by a specific (in the hydrogen bond type) interaction of nitro groups of complexes with a proton solvent.

Litke, S. V.; Mezentseva, T. V.; Litke, A. S.; Lyalin, G. N.; Ershov, A. Yu.

2000-12-01

219

Wideband dye-sensitized solar cells employing a phosphine-coordinated ruthenium sensitizer  

NASA Astrophysics Data System (ADS)

Low-cost renewable energies are necessary for the realization of a low-carbon society. Organic photovoltaics such as organic thin-film solar cells and dye-sensitized solar cells (DSSCs) are promising candidates for realizing low-cost solar cells. However, device efficiencies are still considerably lower than those of traditional inorganic solar cells. To improve organic photovoltaic performance, approaches are needed to extend the absorption of organic compounds to longer wavelengths. Here, we report efficient DSSCs that exploit near-infrared, spin-forbidden singlet-to-triplet direct transitions in a phosphine-coordinated Ru(II) sensitizer, DX1. A DSSC using DX1 generated a photocurrent density of 26.8 mA cm-2, the highest value for an organic photovoltaic reported to date. A tandem-type DSSC employing both DX1 and the traditional sensitizer N719 is shown to have a power conversion efficiency of >12% under 35.5 mW cm-2 simulated sunlight.

Kinoshita, Takumi; Dy, Joanne Ting; Uchida, Satoshi; Kubo, Takaya; Segawa, Hiroshi

2013-07-01

220

Geminal tetraauration of acetonitrile: hemilabile-phosphine-stabilized Au8Ag4 cluster compounds.  

PubMed

Unprecedented geminal tetraauration of acetonitrile has been realized through C-H activation by Au(I)-Ag(I) clusters under mild conditions. The reaction of [OAu3Ag(dppy)3](BF4)2 (dppy = diphenylphosphino-2-pyridine) (1), AgBF4, and acetonitrile in the presence of methanol at room temperature resulted in the isolation of the novel cluster [(CCN)2Au8Ag4(dppy)8(CH3CN)2](BF4)6 (2). The centrosymmetric structure consists of two Au4Ag2 motifs stabilized by hemilabile phosphines. Triply deprotonated acetonitrile (CCN(3-)) is found in a Au4Ag environment with the terminal carbon bridging four Au(I) centers and the nitrogen donor linking a Ag(I) ion, which is the first example of a ?5-CCN(3-) coordination mode. A concerted metalation/deprotonation process for the C-H activation of acetonitrile that indicates the importance of the oxo ion of the oxonium Au(I) cluster is proposed. Cluster 2 emits bright green light in the solid state at room temperature upon UV irradiation. PMID:23581858

Pei, Xiao-Li; Yang, Yang; Lei, Zhen; Wang, Quan-Ming

2013-05-01

221

Photopolymerization of aromatic acrylate containing phosphine oxide backbone and its application to holographic recording  

NASA Astrophysics Data System (ADS)

Photopolymer compositions for holographic recording were prepared from aromatic diacrylate having phosphine oxide backbone, a hybrid sol-gel, and photoinitiator. The physical and holographic properties of photopolymer were controlled by the ratio of precursor triethoxysilylpropyl polyethyleneglycol carbamate (TSPEG) in a hybrid sol-gel binder and the content of monomer. The photopolymerization rate and conversion of monomer were monitored by photo-differential scanning calorimetry (photo-DSC). Holographic recording was attempted by photopolymerization of the monomers in the photopolymer film using a 532 nm laser. Holographic gratings were written into the photopolymer samples by interfering two collimated plane wave beams. The temporal growth of the diffracted power was monitored in real-time at 785 nm laser. Contents of monomer and TESPEG were changed in the range of 0-60 wt% and the composition were optimized in terms of diffraction efficiency. Photopolymer film exhibited very high diffraction efficiency of 93.5% and low shrinkage (<0.5%) after the contents of monomer, binder, and TSPEG were optimized.

Chang, Yu Mi; Yoon, Sung Cheol; Han, Mijeong

2007-12-01

222

Zirconium extraction into octyl(phenyl)-N,N-diisobutylcarbamoylmethyl phosphine oxide and tributyl phosphate  

SciTech Connect

Classical slope analysis techniques were used to determine the octyl(phenyl)-N,N-diisobutylcarbamoylmethyl phosphine oxide (CMPO) and nitrate stoichiometries for the extraction of zirconium by CMPO diluted with diisopropylbenzene (DIPB). The equilibrium constant for the extraction of zirconium by CMPO was also determined using classical slope analysis techniques. The extraction of zirconium by TBP in n-dodecane was used as a control to verify the zirconium species as Zr{sup +4}, and to verify the experimental methodology. Equilibrium [CMPO]{sub org} and [TBP]{sub org} concentrations were determined by accounting for the extraction of HNO{sub 3} into both TBP and CMPO solvents. Nitric acid dissociation and aqueous phase activity coefficients were also taken into consideration. Organic activity coefficients, Zr{sup +4} activity coefficients, Zr{sup +4} hydrolysis, and consumption of TBP or CMPO by water were neglected. Nitrate and CMPO dependencies for the extraction of zirconium have been determined from this work to be: Zr{sub aq}{sup +4} + 4 NO{sub 3 aq}{sup {minus}} + 2 CMPO{sub org} {r_arrow} Zr(NO{sub 3}){sub 4} {sm_bullet} 2 CMPO{sub org}. An equilibrium constant of 1.13 {times} 10{sup 5} {+-} 1.48 {times} 10{sup 4} at 25 C was also determined for this reaction.

Brewer, K.N.; Herbst, R.S.; Todd, T.A.; Christian, J.D. [Lockheed Idaho Technologies Co., Idaho Falls, ID (United States)

1998-07-01

223

Photolysis of phosphine in the presence of acetylene and propyne, gas mixtures of planetary interest  

NASA Astrophysics Data System (ADS)

Phosphine (PH_3) 1 has been observed in the atmospheres of Jupiter and Saturn. We have studied the photochemical reactions of this compound with acetylene (C_2H_2), an alkyne also detected in these atmospheres. The volatile products formed in these reactions were characterized by ^1H, ^31P and ^13C NMR. The ethenylphosphine 2 is the first product formed in the photolysis of PH_3 in the presence of C_2H_2. Photolysis of PH_3 in the presence of propyne (C_3H_4) led to the formation of the Z- and E-prop-1-enylphosphines and traces of 1-methylethenylphosphine. A reaction pathway is proposed. The initial step is the dissociation of PH_3 to hydrogen and PH_2 radicals. Addition of the phosphinyl radical on alkyne occurs as the next step. Vinylphosphines are then formed by radical combination. This proposed reaction pathway takes into account the nature of the products and studies devoted to the photolysis of germane (GeH_4) or hydrogen sulfide (H_2S) in the presence of alkyne. Attempts to detect the methylidynephosphine HC=P (the isoelectronic compound of HC=N), in the photolysis products of PH_3-C_2H_2 mixtures were unsuccessful. The application of these findings to Jovian and Saturn atmospheric chemistry is discussed.

Guillemin, J.-C.; Janati, T.; Lassalle, L.

1995-08-01

224

New phosphine-diamine and phosphine-amino-alcohol tridentate ligands for ruthenium catalysed enantioselective hydrogenation of ketones and a concise lactone synthesis enabled by asymmetric reduction of cyano-ketones  

PubMed Central

Enantioselective hydrogenation of ketones is a key reaction in organic chemistry. In the past, we have attempted to deal with some unsolved challenges in this arena by introducing chiral tridentate phosphine-diamine/Ru catalysts. New catalysts and new applications are presented here, including the synthesis of phosphine-amino-alcohol P,N,OH ligands derived from (R,S)-1-amino-2-indanol, (S,S)-1-amino-2-indanol and a new chiral P,N,N ligand derived from (R,R)-1,2-diphenylethylenediamine. Ruthenium pre-catalysts of type [RuCl2(L)(DMSO)] were isolated and then examined in the hydrogenation of ketones. While the new P,N,OH ligand based catalysts are poor, the new P,N,N system gives up to 98% e.e. on substrates that do not react at all with most catalysts. A preliminary attempt at realising a new delta lactone synthesis by organocatalytic Michael addition between acetophenone and acrylonitrile, followed by asymmetric hydrogenation of the nitrile functionalised ketone is challenging in part due to the Michael addition chemistry, but also since Noyori pressure hydrogenation catalysts gave massively reduced reactivity relative to their performance for other acetophenone derivatives. The Ru phosphine-diamine system allowed quantitative conversion and around 50% e.e. The product can be converted into a delta lactone by treatment with KOH with complete retention of enantiomeric excess. This approach potentially offers access to this class of chiral molecules in three steps from the extremely cheap building blocks acrylonitrile and methyl-ketones; we encourage researchers to improve on our efforts in this potentially useful but currently flawed process.

2012-01-01

225

X-ray structural determination of a bulky phosphine complex: chloro{tris(2,4,6-trimethoxyphenyl)phosphine}gold(I), {AuCl[P(C 9H 11O 3) 3]}  

Microsoft Academic Search

The title compound, {AuCl[P(C9H11O3)3]}, has three fold symmetry in the solid state. The Au?Cl and Au?P bond lengths are 2.294 and 2.255 Å, respectively, and the Au atom has nearly linear coordination geometry, with P?Au?Cl 176.03(9)°. The extreme bulkiness of the phosphine ligand is shown by the mean cone angle of 188° (based on O atoms defining the cone), though

Elmer C Alyea; George Ferguson; Shanmugaperumal Kannan

2000-01-01

226

Air-stable platinum and palladium complexes featuring bis[2,4-bis(trifluoromethyl)phenyl]phosphinous acid ligands.  

PubMed

Secondary phosphane oxides, R(2)P(O)H, are commonly used as preligands for transition-metal complexes of phosphinous acids, R(2)P-OH (R=alkyl, aryl), which are relevant as efficient catalysts in cross-coupling processes. In contrast to previous work by other groups, we are interested in the ligating properties of an electron-deficient phosphinous acid, (R(f))(2)P-OH, bearing the strongly electron-withdrawing and sterically demanding 2,4-bis(trifluoromethyl)phenyl group towards catalysis-relevant metals, such as palladium and platinum. The preligand bis[2,4-bis(trifluoromethyl)phenyl]phosphane oxide, (R(f))(2)P(O)H, reacts smoothly with solid platinum(II) dichloride yielding the trans-configured phosphinous acid platinum complex trans-[PtCl(2)({2,4-(CF(3))(2)C(6)H(3)}(2)POH)(2)]. The deprotonation of one phosphinous acid ligand with an appropriate base leads to the cis-configured monoanion complex cis-[PtCl(2)({2,4-(CF(3))(2)C(6)H(3)}(2)PO)(2)H](-), featuring the quasi-chelating phosphinous acid phosphinito unit, (R(f))(2)P-O-H···O=P(R(f))(2), which exhibits a strong hydrogen bridge substantiated by an O···O distance of 245.1(4) pm. The second deprotonation step is accompanied by a rearrangement to afford the trans-configured dianion trans-[PtCl(2)({2,4-(CF(3))(2)C(6)H(3)}(2)PO)(2)](2-). The reaction of (R(f))(2)P(O)H with solid palladium(II) dichloride initially yields a mononuclear palladium complex [PdCl(2)({2,4-(CF(3))(2)C(6)H(3)}(2)POH)(2)], which condenses under liberation of HCl to the neutral dinuclear palladium complex [Pd(2)(?-Cl)(2){({2,4-(CF(3))(2)C(6)H(3)}(2)PO)(2)H}(2)]. The equilibrium between the mononuclear [PdCl(2)({2,4-(CF(3))(2)C(6)H(3)}(2)POH)(2)] and dinuclear [Pd(2)(?-Cl)(2){({2,4-(CF(3))(2)C(6)H(3)}(2)PO)(2)H}(2)] palladium complexes is reversible and can be shifted in each direction by the addition of base or HCl, respectively. Treatment of palladium(II) hexafluoroacetylacetonate, [Pd(F(6)acac)(2)], with a slight excess of (R(f))(2)P(O)H yields the complex [Pd(F(6)acac)({2,4-(CF(3))(2)C(6)H(3)}(2)PO)(2)H]. The quasi-chelating phosphinous acid phosphinito unit, which is formed by the liberation of HF(6)acac, is characterized by a O···O distance of 244.1(3) pm. These transition metal complexes are stable towards air and moisture and can be stored for months without any evidence of decomposition. PMID:22147659

Kurscheid, Boris; Neumann, Beate; Stammler, Hans-Georg; Hoge, Berthold

2011-12-23

227

Phosphine and methylphosphine production by simulated lightning—a study for the volatile phosphorus cycle and cloud formation in the earth atmosphere  

NASA Astrophysics Data System (ADS)

Phosphine (PH 3), was recently found worldwide even in the remote atmosphere (Naturwissenschaften83(1996a)131; Atmos. Environ. 37(2003)24 29). It is of interest to find natural mechanisms which could produce phosphine gas and drive a volatile link of the atmospheric phosphorus cycle and the formation of phosphoric acid as possible condensation nuclei for clouds. Here, we report on simulated lightning exposing sodium phosphate in a reducing medium (methane model atmosphere or organic matter) for 5 s to a spark induced by microwave. The gas product analyzed by gas chromatography contained phosphine (yield up to 0.6 g kg -1 phosphate P) and methylphosphine (CH 3)PH 2 (yield up to 0.02 g kg -1 phosphate P). We suggest a plasma-chemical formation mechanism where organic compounds or methane or secondary hydrogen thereof reduce phosphate to phosphine of which a small fraction can subsequently react with methyl radicals to form methylphosphine. A small yield of 6 mg phosphine per kg phosphate P was even obtained in methane free medium, by simple plasmatic recombination of inorganic phosphorus. We believe that methane and hydrogen are useful model substances of pyrolytic gases with high reducing power which may form if lightning strikes biomass, soil and aerosol. These results suggest evidence that phosphine and methylphosphine (detectable in the field by intense garlic odor) are produced when atmospheric lightning strikes the ground or aerosol which is containing oxidized forms of phosphorus and chemical reductants. Additional reviewed data show that laboratory lightning was able to reduce a much more significant portion of phosphate to phosphite (up to 25% yield), methylphosphonic acid (up to 8.5% yield) and traces of hypophosphite in a matter of seconds.

Glindemann, Dietmar; Edwards, Marc; Schrems, Otto

228

New highly water-soluble rhodium complexes bearing 1,3,5-triaza-7-phosphaadamantane (PTA) and\\/or tris(hydroxymethyl) phosphine (THP)  

Microsoft Academic Search

A family of cationic and neutral highly water-soluble rhodium complexes [Cp?Rh(PTA)3]Cl2 (1), [Cp?RhCl2(THP)] (2), [Cp?RhCl(THP)2]Cl (3), and [Cp?RhCl(PTA)(THP)]Cl (4) have been synthesised and fully characterised [PTA=1,3,5-triaza-7-phosphaadamantane; THP=tris(hydroxymethyl)phosphine]. Their water-solubility increases as the number of the phosphines coordinated to the metal centre is increased. The X-ray crystal structure of compound 2 was obtained and shows the presence of intermolecular hydrogen bonding.

Sandra Bolaño; Maider Plaza; Jorge Bravo; Jesús Castro; Maurizio Peruzzini; Luca Gonsalvi; Gianluca Ciancaleoni; Alceo Macchioni

2010-01-01

229

Apparatus for purifying arsine, phosphine, ammonia, and inert gases to remove Lewis acid and oxidant impurities therefrom  

DOEpatents

An apparatus for purifying a gaseous mixture comprising arsine, phosphine, ammonia, and/or inert gases, to remove Lewis acid and/or oxidant impurities therefrom, comprising a vessel containing a bed of a scavenger, the scavenger including a support having associated therewith an anion which is effective to remove such impurities, such anion being selected from one or more members of the group consisting of: (i) carbanions whose corresponding protonated compounds have a pK.sub.a value of from about 22 to about 36; and (ii) anions formed by reaction of such carbanions with the primary component of the mixture.

Tom, Glenn M. (New Milford, CT); Brown, Duncan W. (Wilton, CT)

1991-01-08

230

Evidence for erbium-erbium energy migration in erbium(III) bis(perfluoro-p-tolyl)phosphinate  

NASA Astrophysics Data System (ADS)

Photoluminescence lifetime measurements of the erbium decay in samples of erbium(III) bis(perfluoro-p-tolyl)phosphinate, Er[(p-CF3C6F4)2PO2]3, as a function of erbium concentration have been made. It has been found that for concentrations greater than 50%, the lifetime could be fitted with a stretched exponential function, which is indicative of erbium-erbium energy migration to quenching sites, most likely at the surface of the finely divided powder. At concentrations below 50%, the decay was single exponential with a maximum lifetime of ~700 ?s.

Tan, R. H. C.; Pearson, J. M.; Zheng, Y.; Wyatt, P. B.; Gillin, W. P.

2008-03-01

231

Anaerobic utilization of phosphite/phosphine as a sole source of phosphorus - Implication to growth in the Jovian environment  

NASA Technical Reports Server (NTRS)

The ability of anaerobic soil isolate microorganisms to metabolize hypophosphite as the sole phosphorus source was studied. Isolates were inoculated into defined medium; growth was determined by turbidity readings, and concentrations of P-32-hypophosphite and its metabolites were determined. Evidence for growth was obtained. Experiments will be performed to see if anaerobes can use phosphine as a sole phosphorous source; the ability of earth organisms to utilize reduced forms of phosphorus would suggest that contaminating organisms from earth would not be eliminated by the absence of phosphate in the Jovian atmosphere.

Foster, T. L.; Winans, L., Jr.

1977-01-01

232

Triphenyl phosphine adducts of platinum(IV) and palladium(II) dithiocarbamates complexes: a spectral and in vitro study  

NASA Astrophysics Data System (ADS)

Triphenyl phosphine adducts of dithiocarbamate complexes of platinum(IV) and palladium(II) of the type [Pt(L) 2PPh 3Cl 2] and [Pd(L) 2PPh 3] [L: morpholine dithiocarbamate (L 1), aniline dithiocarbamate (L 2) and N-(methyl, cyclohexyl) dithiocarbamate (L 3)] were prepared and characterized by elemental analysis, electronic, IR, 1H NMR and 13C NMR spectral studies. Thermal studies of the complexes were carried out. In vitro antitumor activity has been screened towards human adenocarcinoma cell lines and showed significant inhibition even at very low concentration.

Manav, N.; Mishra, A. K.; Kaushik, N. K.

2004-11-01

233

Parahydrogen derived illumination of pyridine based coordination products obtained from reactions involving rhodium phosphine complexes.  

PubMed

The reactions of RhCl(PBz3)3 with H2 and pyridine or 4-methylpyridine yield RhCl(H)2(PBz3)2(py) and RhCl(H)2(PBz3)2(4-Me-py), respectively. These species undergo hydride site exchange via the loss of the pyridyl donor and formation of RhCl(H)2(PBz3)2 which contains equivalent hydride ligands; for the py system the activation free energy, deltaG++300, is 57.4 +/- 0.1 kJ mol(-1) while for 4-Me-py the value is 59.6 +/- 0.3 kJ mol(-1). These products only showed parahydrogen enhancement in the corresponding hydride resonances when a sacrificial substrate was added to promote hydrogen cycling. When RhCl(PPh3)3 was used as the precursor similar observations were made, while when RhCl(PCy3)2(C2H4) was examined, H2 addition led to the formation of the binuclear complex (H)2Rh(PCy3)2(micro-Cl)2Rh(H)2(PCy3)2 which was differentiated from RhCl(H)2(PCy3)2 on the basis of the similarity in diffusion coefficient (5.5 x 10(-9) m2 s(-1)) to that of (H)2Rh(PPh3)2(micro-Cl)2Rh(PPh3)2 (5.3 x 10(-9) m2 s(-1)). The detection of RhCl(H)2(PCy3)2(py) was facilitated when pyridine was added to a solution of RhCl(PCy3)2(C2H4) before the introduction of H2. During these reactions trace amounts of the double substitution products, RhCl(H)2(phosphine)(py)2, were also detected. PMID:16471059

Zhou, Rongrong; Aguilar, Juan A; Charlton, Adrian; Duckett, Simon B; Elliott, Paul I P; Kandiah, Rathika

2005-12-01

234

Evaluation of headspace solid-phase microextraction for analysis of phosphine residues in wheat.  

PubMed

In headspace (HS) analysis, a fumigant is released from a commodity into a gas-tight container by grinding, heating, or microwaves. A new technique uses HS-solid-phase microextraction (SPME) for additional preconcentration of fumigant. HS-SPME was tested for detection of phosphine (PH3), chosen for examination because of its wide use on stored commodities. PH3 was applied to 50 g wheat in separate 250 mL sealed flasks, which were equipped either with a septum for conventional HS analysis or with one of four HS-SPME fibers [100 microm polydimethylsiloxane (PDMS), 85 microm carboxen (CAR)/PDMS, 75 microm CAR/PDMS, and 65 pm PDMS/divinylbenzene (DVB)]. The wheat was heated at 45 degrees C for 20 min. In conventional HS analysis, a gaseous aliquot (80 pL) was taken from the HS and injected into the GC instrument. In the HS-SPME procedure, the fiber was removed from the HS and exposed in the heated injection port of the GC instrument. In all cases, PH3 was determined under the same chromatographic conditions with a GC pulsed flame photometric detector. In a comparison of the efficacy of the fibers, the bipolar fibers (CAR/PDMS and PDMS/DVB) contained more PH3 than the aliquot in the conventional HS analysis; larger size bipolar fibers extracted PH3 more efficiently than smaller fibers (e.g., 85 > 75 > 65 microm). The nonpolar fiber (PDMS) contained no PH3. Four fortification levels of PH3 on wheat were tested: 0.01, 0.05, 0.1, and 0.3 microg/g. The response of each bipolar fiber increased with the fortification levels, but the conventional HS analysis detected no fumigant at the lowest fortification level of 0.01 mg/g. Under the conditions of the validation study, the LOD was in the range of 0.005-0.01 ng PH3/g wheat. PMID:22649943

Ren, Yong Lin; Padovan, Benjamin; Desmarchelier, James M

2012-01-01

235

In vitro antitumor activity of the water soluble copper(I) complexes bearing the tris(hydroxymethyl)phosphine ligand.  

PubMed

Monocationic hydrophilic complexes [Cu(thp)4](+) 3 and [Cu(bhpe)2](+) 4 were synthesized by ligand exchange reactions starting from the labile [Cu(CH3CN)4][PF6] precursor in the presence of an excess of the relevant hydrophilic phosphine. Complexes 3 and 4 were tested against a panel of several human tumor cell lines. Complex 3 has been shown to be about 1 order of magnitude more cytotoxic than cisplatin. Chemosensitivity tests performed on cisplatin and multidrug resistance phenotypes suggested that complex 3 acts via a different mechanism of action than the reference drug. Different short-term proliferation assays suggested that lysosomal damage is an early cellular event associated with complex 3 cytotoxicity, probably mediated by an increased production of reactive oxygen species. Cytological stains and flow cytometric analyses indicated that the phosphine copper(I) complex is able to inhibit the growth of tumor cells via G2/M cell cycle arrest and paraptosis accompanied with the loss of mitochondrial transmembrane potential. PMID:18251492

Marzano, Cristina; Gandin, Valentina; Pellei, Maura; Colavito, Davide; Papini, Grazia; Lobbia, Giancarlo Gioia; Del Giudice, Elda; Porchia, Marina; Tisato, Francesco; Santini, Carlo

2008-02-28

236

A Stereoselective Synthesis of Phosphinic Acid Phosphapeptides Corresponding to Glutamyl-?-glutamate and Incorporation into Potent Inhibitors of Folylpoly-?-glutamyl Synthetase  

PubMed Central

Radical addition of H3PO2 to N-/C-protected vinyl glycine led to the corresponding H-phosphinic acid in excellent yield. The non-nucleophilic H-phosphinic acid was converted to a nucleophilic PIII species, RP(OTMS)2, which was used in two approaches to the target phosphinic acid containing pseudopeptide. New methodology was developed that led to excellent yields in the reaction of RP(OTMS)2 with unactivated electrophiles, including an acyclic homoallylic bromide. However, en route to the target pseudopeptide, Arbuzov reaction of RP(OTMS)2 with a cyclic homoallylic bromide, (R)-3-(bromomethyl)-cyclopent-1-ene, led to a rearranged allylic phosphinic acid rather than the desired homoallylic derivative, a putative glutarate surrogate. Conjugate addition of RP(OTMS)2 to ?-methylene glutarate containing a chiral auxiliary resulted in only modest diastereoselectivity. Purification by flash chromatography provided protected derivatives of both diastereomers of the pseudopeptide. Following global deprotection, coupling of (S)-H-Glu-?[?(P(O)(OH)(CH2))]-(S)-Glu- OH and (S)-H-Glu-?-[?(P(O)(OH)(CH2))]-(R)-Glu-OH to (4-amino-4-deoxy-10-methyl)pteroyl azide led to the target compounds for biochemical study as inhibitors of the ATP-dependent ligase, folylpoly-?-glutamate synthetase.

Bartley, David M.; Coward, James K.

2007-01-01

237

Synthesis of Unsymmetrically Substituted Phosphane Oxides (R(1) R(2) P(O)H) and Phosphinous Acids (R(1) R(2) POH).  

PubMed

Invited for the cover of this issue is the group of Berthold Hoge at the University of Bielefeld. The image depicts the delicate balance between the unusual form of a phosphinous acid with respect to the corresponding phosphane oxide tautomer by the influence of electron-withdrawing groups. Read the full text of the article at 10.1002/chem.201402425. PMID:24957356

Allefeld, Nadine; Grasse, Michael; Ignat'ev, Nikolai; Hoge, Berthold

2014-07-01

238

The rph1 gene is a common contributor to the evolution of phosphine resistance in independent field isolates of Rhyzopertha dominica.  

PubMed

Phosphine is the only economically viable fumigant for routine control of insect pests of stored food products, but its continued use is now threatened by the world-wide emergence of high-level resistance in key pest species. Phosphine has a unique mode of action relative to well-characterised contact pesticides. Similarly, the selective pressures that lead to resistance against field sprays differ dramatically from those encountered during fumigation. The consequences of these differences have not been investigated adequately. We determine the genetic basis of phosphine resistance in Rhyzopertha dominica strains collected from New South Wales and South Australia and compare this with resistance in a previously characterised strain from Queensland. The resistance levels range from 225 and 100 times the baseline response of a sensitive reference strain. Moreover, molecular and phenotypic data indicate that high-level resistance was derived independently in each of the three widely separated geographical regions. Despite the independent origins, resistance was due to two interacting genes in each instance. Furthermore, complementation analysis reveals that all three strains contain an incompletely recessive resistance allele of the autosomal rph1 resistance gene. This is particularly noteworthy as a resistance allele at rph1 was previously proposed to be a necessary first step in the evolution of high-level resistance. Despite the capacity of phosphine to disrupt a wide range of enzymes and biological processes, it is remarkable that the initial step in the selection of resistance is so similar in isolated outbreaks. PMID:22363668

Mau, Yosep S; Collins, Patrick J; Daglish, Gregory J; Nayak, Manoj K; Pavic, Hervoika; Ebert, Paul R

2012-01-01

239

A multifunctional phosphine oxide-diphenylamine hybrid compound as a high performance deep-blue fluorescent emitter and green phosphorescent host.  

PubMed

A novel phosphine oxide-diphenylamine hybrid compound POA was designed and synthesized with the aim of developing new multifunctional blue fluorophores. POA is the first kind of compound that can be used as a high-efficiency deep-blue emitter (5.4% EQE) and a host to fabricate high-performance green phosphorescent OLEDs (18.1% EQE). PMID:24413567

Liu, Xiao-Ke; Zheng, Cai-Jun; Lo, Ming-Fai; Xiao, Jing; Lee, Chun-Sing; Fung, Man-Keung; Zhang, Xiao-Hong

2014-02-25

240

A direct, modular, and efficient construction of the P-C-P structural motif through coupling of manganese carbyne complexes with phosphines.  

PubMed

Easily available carbyne complexes of manganese were used as a source of carbyne fragments in an unconventional synthesis of backbone-substituted diphosphinomethanes and cyclic P-ylides upon coupling with secondary or tertiary phosphines, respectively, followed by demetalation under mild conditions. PMID:24482143

Valyaev, Dmitry A; Bastin, Stéphanie; Utegenov, Kamil I; Lugan, Noël; Lavigne, Guy; Ustynyuk, Nikolai A

2014-02-17

241

Phosphine-Catalyzed Annulations of Azomethine Imines: Allene-Dependent [3 + 2], [3 + 3], [4 + 3], and [3 + 2 + 3] Pathways  

PubMed Central

In this paper we describe the phosphine-catalyzed [3 + 2], [3 + 3], [4 + 3], and [3 + 2 + 3] annulations of azomethine imines and allenoates. These processes mark the first use of azomethine imines in nucleophilic phosphine catalysis, producing dinitrogen-fused heterocycles, including tetrahydropyrazolo-pyrazolones, -pyridazinones, -diazepinones, and -diazocinones. Counting the two different reaction modes in the [3 + 3] cyclizations, there are five distinct reaction pathways—the choice of which depends on the structure and chemical properties of the allenoate. All reactions are operationally simple and proceed smoothly under mild reaction conditions, affording a broad range of 1,2-dinitrogen–containing heterocycles in moderate to excellent yields. A zwitterionic intermediate formed from a phosphine and two molecules of ethyl 2,3-butadienoate acted as a 1,5-dipole in the annulations of azomethine imines, leading to the [3 + 2 + 3] tetrahydropyrazolodiazocinone products. The incorporation of two molecules of an allenoate into an eight-membered-ring product represents a new application of this versatile class of molecules in nucleophilic phosphine catalysis. The salient features of this protocol—the facile access to a diverse range of nitrogen-containing heterocycles and the simple preparation of azomethine imine substrates—suggest that it might find extensive applications in heterocycle synthesis.

Na, Risong; Jing, Chengfeng; Xu, Qihai; Jiang, Hui; Wu, Xi; Shi, Jiayan; Zhong, Jiangchun; Wang, Min; Benitez, Diego; Tkatchouk, Ekaterina; Goddard, William A.; Guo, Hongchao; Kwon, Ohyun

2011-01-01

242

Direct evidence for the availability of reactive, water soluble phosphorus on the early Earth. H-phosphinic acid from the Nantan meteorite.  

PubMed

Anoxic irradiation of a type IIICD iron meteorite known to contain the phosphide mineral schreibersite (Fe,Ni)3P in the presence of ethanol/water affords the reactive oxyacid H-phosphinic acid (H3PO2) as the dominant phosphorus product. PMID:16733574

Bryant, David E; Kee, Terence P

2006-06-14

243

Synthesis and reactions of Cp-linked phosphine complexes of rhodium  

SciTech Connect

The linked Cp ligand [C{sub 5}H{sub 4}SiMe{sub 2}CH{sub 2}PPh{sub 2}]{sup {minus}} has been used to synthesize several rhodium derivatives. Reaction with [RhClL{sub 2}]{sub 2} where L = C{sub 2}H{sub 4}, C{sub 8}H{sub 14}, or CO, gives ({eta}{sup 5}:{eta}{sup 1}-C{sub 5}H{sub 4}SiMe{sub 2}-CH{sub 2}PPh{sub 2})Rh(L) complexes, which have been characterized by single-crystal X-ray diffraction. Reaction of the ethylene complex with CO or PMe{sub 3} gives the carbonyl- and phosphine-substituted derivatives, respectively. Irradiation of the ethylene complex in the presence of hydrogen gives a new binuclear polyhydride, also structurally characterized, in which the chelating ligand spans the two metal centers. Reaction of the ethylene complex with iodine leads to the formation of the diiodide ({eta}{sup 5}:{eta}{sup 1}-C{sub 5}H{sub 4}SiMe{sub 2}CH{sub 2}PPh{sub 2})RhI{sub 2}, which in turn can be converted to the dihydride ({eta}{sup 5}:{eta}{sup 1}-C{sub 5}H{sub 4}SiMe{sub 2}CH{sub 2}PPh{sub 2})RhH{sub 2} by reaction with NaAl(OCH{sub 2}CH{sub 2}OCH{sub 3}){sub 2}H{sub 2}. The reactivity of the dihydride toward C-H bond activation has been investigated. While benzene does not give a stable oxidative addition adduct, pentafluorobenzene yields ({eta}{sup 5}:{eta}{sup 1}-C{sub 5}H{sub 4}SiMe{sub 2}CH{sub 2}PPh{sub 2})Rh(C{sub 6}F{sub 5})H, which was structurally characterized as its chloro derivative. Reaction of the dihydride with C{sub 6}F{sub 6} gives the {eta}{sup 2} complex ({eta}{sup 5}:{eta}{sup 1}-C{sub 5}H{sub 4}SiMe{sub 2}CH{sub 2}PPh{sub 2})Rh({eta}{sup 2}-C{sub 6}F{sub 6}), also structurally characterized.

Lefort, L.; Crane, T.W.; Farwell, M.D.; Baruch, D.M.; Kaeuper, J.A.; Lachicotte, R.J.; Jones, W.D. [Univ. of Rochester, NY (United States). Dept. of Chemistry] [Univ. of Rochester, NY (United States). Dept. of Chemistry

1998-08-31

244

Synthesis of Monomeric Fe(II) and Ru(II) Complexes of Tetradentate Phosphines  

SciTech Connect

rac-Bis[{l_brace}(diphenylphosphino)ethyl{r_brace}-phenylphosphino]methane (DPPEPM) reacts with iron(II) and ruthenium(II) halides to generate complexes with folded DPPEPM coordination. The paramagnetic, five-coordinate Fe(DPPEPM)Cl{sub 2} (1) in CD{sub 2}Cl{sub 2} features a tridentate binding mode as established by {sup 31}P{l_brace}{sup 1}H{r_brace} NMR spectroscopy. Crystal structure analysis of the analogous bromo complex, Fe(DPPEPM)Br{sub 2} (2) revealed a pseudo-octahedral, cis-{alpha} geometry at iron with DPPEPM coordinated in a tetradentate fashion. However, in CD{sub 2}Cl{sub 2} solution, the coordination of DPPEPM in 2 is similar to that of 1 in that one of the external phosphorus atoms is dissociated resulting in a mixture of three tridentate complexes. The chloro ruthenium complex cis-Ru({kappa}{sup 4}-DPPEPM)Cl{sub 2} (3) is obtained from rac-DPPEPM and either [RuCl{sub 2}(COD)]{sub 2} [COD = 1,5-cyclooctadiene] or RuCl{sub 2}(PPh{sub 3}){sub 4}. The structure of 3 in both the solid state and in CD{sub 2}Cl{sub 2} solution features a folded {kappa}{sup 4}-DPPEPM. This binding mode was also observed in cis-[Fe({kappa}{sup 4}-DPPEPM)(CH{sub 3}CN){sub 2}](CF{sub 3}SO{sub 3}){sub 2} (4). Addition of an excess of CO to a methanolic solution of 1 results in the replacement of one of the chloride ions by CO to yield cis-[Fe({kappa}{sup 4}-DPPEPM)Cl(CO)](Cl) (5). The same reaction in CH{sub 2}Cl{sub 2} produces a mixture of 5 and [Fe({kappa}{sup 3}-DPPEPM)Cl{sub 2}(CO)] (6) in which one of the internal phosphines has been substituted by CO. Complexes 2, 3, 4, and 5 appear to be the first structurally characterized monometallic complexes of {kappa}{sup 4}-DPPEPM.

Jana, Barun; Ellern, Arkady; Pestovsky, Oleg; Sadow, Aaron; Bakac, Andreja

2011-03-07

245

Phosphorescent Cu(I) complexes of 2-(2'-pyridylbenzimidazolyl)benzene: impact of phosphine ancillary ligands on electronic and photophysical properties of the Cu(I) complexes.  

PubMed

Four mononuclear Cu(I) complexes of 2-(2'-pyridyl)benzimidazolylbenzene (pbb) with four different ancillary phosphine ligands PPh(3), bis[2-(diphenylphosphino)phenyl]ether (DPEphos), bis(diphenylphosphino)ethane (dppe), and bis(diphenylphosphinomethyl)diphenylborate (DPPMB) have been synthesized. The crystal structures of [Cu(pbb)(PPh(3))(2)][BF(4)] (1), [Cu(pbb)(dppe)][BF(4)] (2), [Cu(pbb)(DPEphos)][BF(4)] (3), and the neutral complex [Cu(pbb)(DPPMB)] (4) were determined by single-crystal X-ray diffraction analyses. The impact of the phosphine ligands on the structures of the copper(I) complexes was examined, revealing that the most significant impact of the phosphine ligands is on the P-Cu-P bond angle. The electronic and photophysical properties of the new complexes were examined by using UV-vis, fluorescence, and phosphorescence spectroscopies and electrochemical analysis. All four complexes display a weak MLCT absorption band that varies considerably with the phosphine ligand. At ambient temperature, no emission was observed for any of the complexes in solution. However, when doped into PMMA polymer (20 wt %), at ambient temperature, all four complexes emit light with a color ranging from green to red-orange, depending on the phosphine ligand. The emission of the new copper complexes has an exceptionally long decay lifetime (>200 micros). Ab initio MO calculations established that the lowest electronic transition in the copper(I) complexes is MLCT in nature. The electronic and photophysical properties of the new mononuclear Cu(I) complexes were compared with those of the corresponding polynuclear Cu(I) complexes based on the 2-(2'-dipyridyl)benzimidazolyl derivative ligands and the previously extensively studied phenanthroline-based Cu(I) complexes. PMID:16390050

McCormick, Theresa; Jia, Wen-Li; Wang, Suning

2006-01-01

246

Summary of GPC/DV results for space exposed poly(arylene ether phosphine oxide)s  

NASA Technical Reports Server (NTRS)

Gel Permeation Chromatography (GPC) was used to analyze poly(arylene ether phosphine oxide)s whose backbones were identical except for the ketone content and placement. These samples were exposed to low Earth orbit environment (predominantly atomic oxygen) on space shuttle flights. The materials and their unexposed controls were then characterized by GPC to investigate the effect of atomic oxygen on the molecular weight distributions. Analysis of the soluble portion of the samples revealed that there was significant loss of high molecular weight species. The presence of insoluble material also suggested that crosslinking was induced by the atomic oxygen exposure and that this very likely occurred at the high molecular weight portion of the molecular weight distribution.

Siochi, Emilie

1995-01-01

247

Rhodium phosphine-phosphite catalysts in the hydrogenation of challenging N-(3,4-dihydronaphthalen-2-yl) amide derivatives.  

PubMed

The enantioselective catalytic hydrogenation of N-(3,4-dihydronaphthalen-2-yl) amides (1) with rhodium catalysts bearing phosphine-phosphite ligands 4 has been studied. A wide catalyst screening, facilitated by the modular structure of 4, has found a highly enantioselective catalyst for this reaction. This catalyst gives a 93% ee in the hydrogenation of 1a and also produces high enantioselectivities, ranging from 83 to 93% ee, in the hydrogenation of several OMe- and Br-substituted substrates. In contrast, the structurally related enol esters 2 are very reluctant to undergo hydrogenation. A coordination study of the representative enamide 1d has shown an unusual ?(6)-arene coordination mode, over the typical O,C,C chelating mode for enamides, as the preferred one for this substrate in a Rh(I) complex. Deuteration reactions of 1c,d indicate a clean syn addition of deuterium to the double bond without an isotopic effect on the enantioselectivity. PMID:23485121

Arribas, Inmaculada; Rubio, Miguel; Kleman, Patryk; Pizzano, Antonio

2013-04-19

248

Carbon-yl(N-nitroso-N-oxido-1-naphtylamine-?O,O')(triphenyl-phosphine-?P)rhodium(I) acetone solvate.  

PubMed

The title compound, [Rh(C(10)H(7)N(2)O(2))(C(18)H(15)P)(CO)]·(CH(3))(2)CO, is the second structural report of a metal complex formed with the O,O'-C(10)H(7)N(2)O(2) (neocupferrate) ligand. In the crystal structure, the metal centre is surrounded by one carbonyl ligand, one triphenyl-phosphine ligand and the bidentate neocupferrate ligand, forming a distorted square-planar RhCO(2)P coordination set which is best illustrated by the small O-Rh-O bite angle of 77.74?(10)°. There are no classical hydrogen-bond inter-actions observed for this complex. PMID:21578610

Venter, Johan A; Purcell, W; Visser, H G; Muller, T J

2009-01-01

249

Preparation of carbonyl phosphine rhodium complexes with dithiolate bridges. Application as catalyst precursors in the hydroformylation of 1-hexene  

Microsoft Academic Search

The reactivity of [Rh2(?-S(CH2)nS)(CO)4] (n = 2, 3 or 4) have been investigated and mixed carbonyl phosphine complexes [Rh2(?-S(CH2)nS)(CO)2(PR3)2]x (R = C6H5, C6H11, O-2-tBuC6H4; n = 2, 3 and 4; x = 1 or 2) have been prepared and studied by IR, 31P-1H NMR and FAB mass spectrometry. Dinuclear complexes [Rh2(?-S(CH2)2S)(CO)2(PR3)2] (R = C6H5, C6H11, O-2-tBuC6H4) and tetranuclear [{Rh2(?-S(CH2)4S)(CO)2}P(O-2-tBuC6H4)3{2}2] formulations

A. Aaliti; A. M. Masdeu; A. Ruiz; C. Claver

1995-01-01

250

Heteroatom-substituted secondary phosphine oxides (HASPOs) as decomposition products and preligands in rhodium-catalysed hydroformylation.  

PubMed

O,O'-3,3'-Di-tert-butyl-5,5'-dimethoxy-1,1'-biphenyl-2,2'-diyl phosphonate (1) is the hydrolysis product of several mono- and bis-phosphites used as ligands in industrial hydroformylation and other catalytic reactions. As a result of a tautomeric equilibrium, this pentavalent heteroatom-substituted phosphine oxide (HASPO) can rearrange to the corresponding trivalent phosphorus compound. The latter is able to react with typical rhodium-containing precursors frequently used for the generation of catalysts. The resulting species were characterised by NMR spectroscopy and X-ray structure analysis. Proof is given that a rhodium complex of 1 forms an active hydroformylation catalyst. Moreover, 1 can add to aldehydes, which are generated as products in the hydroformylation. Thus a broad range of subsequent reactions can be associated with the degradation of the original phosphite ligands, which has a strong influence on the overall outcome of the hydroformylation reaction. PMID:21294179

Christiansen, Andrea; Selent, Detlef; Spannenberg, Anke; Köckerling, Martin; Reinke, Helmut; Baumann, Wolfgang; Jiao, Haijun; Franke, Robert; Börner, Armin

2011-02-11

251

Crystal structure and computational investigation of an analogue of Grubbs' second generation catalyst with a fluorous phosphine.  

PubMed

A fluorous phosphine analogue of Grubbs' second generation olefin metathesis catalyst, (H(2)IMes)((R(f8)(CH(2))(2))(3)P)(Cl)(2)Ru(=CHPh) (1; H(2)IMes/R(f8) = 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene/(CF(2))(7)CF(3)) is crystallized and the X-ray structure analyzed in detail. The bond lengths and angles about ruthenium are compared to those of two solvates and five derivatives of Grubbs' second generation catalyst. All exhibit distorted square pyramidal geometries in which the alkylidene ligands occupy apical positions, and geometric trends are interpreted with the help of density functional calculations. The perfluoroalkyl groups (1) exhibit helical conformations, as manifested by various torsional relationships, (2) segregate in the lattice, and (3) align in pairs of opposite helical chiralities. PMID:22954330

Tuba, Robert; Brothers, Edward N; Reibenspies, Joseph H; Bazzi, Hassan S; Gladysz, John A

2012-09-17

252

Mixed-metal cluster chemistry VI: Phosphine substitution at CpMoIr 3( ?-CO) 3(CO) 8; X-ray crystal structure of CpMoIr 3( ?-CO) 3(CO) 7(PPh 3)  

Microsoft Academic Search

Reactions of CpMoIr3(?-CO)3(CO)8 (1) with stoichiometric amounts of phosphines afford the substitution products CpMoIr3(?-CO)3(CO)8?x (L)x (L = PPh3, x = 1 (2), 2 (3); L = PMe3, x = 1 (4), 2 (5), 3 (6)) in fair to good yields (23–54%); the yields of both 3 and 6 are increased on reacting 1 with excess phosphine. Products 2–5 are fluxional

Nigel T. Lucas; Ian R. Whittall; Mark G. Humphrey; David C. R. Hockless; M. P. Seneka Perera; Michael L. Williams

1997-01-01

253

Heteroleptic silver(I) complexes prepared from phenanthroline and bis-phosphine ligands.  

PubMed

The heteroleptic coordination scenario of silver(I) with various phenanthroline ligands (NN) and different bis-phosphine (PP) derivatives has been investigated. In addition to the X-ray crystal structural characterization of the resulting mixed ligand Ag(I) complexes, detailed NMR studies have been performed to disclose the behavior of the prepared silver(I) complexes in solution. The results obtained with silver(I) have been also systematically related to the one obtained for copper(I) with the same combination of PP and NN ligands. Starting from an equimolar mixture of AgBF4, bis[(2-diphenylphosphino)phenyl] ether (POP), and 1,10-phenanthroline (phen), the mononuclear complex [Ag(POP)(phen)](+) has been obtained as the tetrafluoroborate salt. By following the same experimental procedure starting from bis(diphenylphosphino)methane (dppm) or 1,3-bis(diphenylphosphino)propane (dppp) as the PP ligand, dinuclear complexes with two bridging PP ligands, i.e., [Ag2(NN)2(?-dppm)2](2+) and [Ag2(NN)2(?-dppp)2](2+) with NN = phen or Bphen (bathophenanthroline), have been isolated as the tetrafluoroborate salts. Surprisingly, by using an equimolar ratio of AgBF4, phen or Bphen, and 1,2-bis(diphenyl-phosphino)ethane (dppe), the corresponding monobridged diphosphine dinuclear complexes [Ag2(NN)2(?-dppe)](2+) have been obtained as the tetrafluoroborate salts. These compounds have been also prepared in excellent yield by using a more appropriate 2:1:2 (phen:dppe:Ag) stoichiometry. These results prompted us to also perform the reactions with dppm and dppp using a 1:2:2 (PP:NN:Ag) stoichiometry. Under these conditions, [Ag2(NN)2(?-dppm)](BF4)2 (NN = phen or Bphen) and [Ag2(NN)2(?-dppp)](BF4)2 (NN = phen or Bphen) have been obtained upon crystallization. When compared to their copper(I) analogues, the complexation scenario becomes more complex with silver(I) as the system tolerates also coordinatively frustrated metal ligand assemblies, i.e., with a trigonal coordination geometry. Depending on the stoichiometry or on the nature of the PP partner, silver(I) shows an adaptive capability leading to various complexes with different coordination geometries and composition. However, as in the case of copper(I), their solution behavior is highly dependent on the relative thermodynamic stability of the various possible complexes. In most of the cases, a single Ag(I) complex is observed in solution and the NMR data are in a perfect agreement with their solid state structures. The dppp-containing complexes are the only notable exception; both [Ag2(NN)2(?-dppp)2](BF4)2 and [Ag2(NN)2(?-dppp)](BF4)2 are stable in the solid state but a dynamic mixture is observed as soon as these compounds are dissolved. Finally, whereas both dppe and dppp are chelating ligands for copper(I), it is not the case anymore with silver(I) for which a destabilization of species with chelating dppe and dppp ligands is clearly suggested by our results. PMID:24279392

Kaeser, Adrien; Delavaux-Nicot, Béatrice; Duhayon, Carine; Coppel, Yannick; Nierengarten, Jean-François

2013-12-16

254

A guide to Sonogashira cross-coupling reactions: the influence of substituents in aryl bromides, acetylenes, and phosphines.  

PubMed

The conversion-time data for 168 different Pd/Cu-catalyzed Sonogashira cross-coupling reactions of five arylacetylenes (phenylacetylene; 1-ethynyl-2-ethylbenzene; 1-ethynyl-2,4,6-R(3)-benzene (R = Me, Et, i-Pr)) and Me(3)SiCCH with seven aryl bromides (three 2-R-bromobenzenes (R = Me, Et, i-Pr); 2,6-Me(2)-bromobenzene and three 2,4,6-R(3)-bromobenzenes (R = Me, Et, i-Pr)) with four different phosphines (P-t-Bu(3), t-Bu(2)PCy, t-BuPCy(2), PCy(3)) were determined using quantitative gas chromatography. The stereoelectronic properties of the substituents in the aryl bromides, acetylenes, and phosphines were correlated with the performance in Sonogashira reactions. It was found that the nature of the most active Pd/PR(3) complex for a Sonogashira transformation is primarily determined by the steric bulk of the acetylene; ideal catalysts are: Pd/P-t-Bu(3) or Pd/t-Bu(2)PCy for sterically undemanding phenylacetylene, Pd/t-BuPCy(2) for 2- and 2,6-substituted arylacetylenes or Me(3)SiCCH and Pd/PCy(3) for extremely bulky acetylenes and aryl bromides. Electron-rich and sterically demanding aryl bromides with substituents in the 2- or the 2,6-position require larger amounts of catalyst than 4-substituted aryl bromides. The synthesis of tolanes with bulky groups at one of the two aryl rings is best done by placing the steric bulk at the arylacetylene, which is also the best place for electron-withdrawing substituents. PMID:22390837

Schilz, Marc; Plenio, Herbert

2012-03-16

255

Synthesis, properties, and antitumor effects of a new mixed phosphine gold(I) compound in human colon cancer cells.  

PubMed

The antineoplastic potential of a new stable mixed phosphine gold(I) complex containing tris(tert-butyl)phosphine (tBu3P) and bis(diphenylphosphino)ethene (dppet), namely [Au(tBu3P)(dppet)Cl], has been investigated in the human colon cancer HCT-116 cell line. The (31)P NMR solution study, confirms the structural features observed in the solid state and, in addition, indicates partial formation of dinuclear cationic [Au(tBu3P)2](+) and [Au(dppet)2](+) species. The ionic character and strong Au-P bonds of this gold(I) species are similar to those of the most active antitumor gold compounds so far studied. The title compound was found to exhibit strong cytotoxicity, showing 85 fold greater toxicity than cisplatin (IC50=0.45?M vs IC50=39.16 for cisplatin at 24h) on the HCT-116 line. The cytotoxic effects were, at least partly, mediated by the induction of apoptotic cell death as evidenced by the sub-G1 cell accumulation, oligonucleosomal DNA fragmentation, caspase-3 activation and the release of cytochrome c from the mitochondria. The gold(I) compound showed little interaction with DNA measured through fluorescence quenching studies with calf thymus DNA. The inhibitory effect of the gold(I) compound on intracellular redox proteins has been also observed in pretreated HCT-116 cells. The compound was particularly effective in inhibiting thioredoxin reductase, that is likely responsible for the increased ROS production, and subsequent apoptosis induction via the mitochondrial pathway. PMID:23632460

Lupidi, Giulio; Avenali, Luca; Bramucci, Massimo; Quassinti, Luana; Pettinari, Riccardo; Khalife, Hala K; Gali-Muhtasib, Hala; Marchetti, Fabio; Pettinari, Claudio

2013-07-01

256

Regioselectivity of the photochemical addition of phosphine to unsaturated hydrocarbons in the atmospheres of Jupiter and Saturn.  

PubMed

Phosphine (PH3) has been observed in the atmospheres of Jupiter and Saturn. We have studied the regioselectivity in the gaseous phase of the photochemical addition of PH3 to propene 1, propadiene 2, propyne 3, 1,3-butadiene 4 and 1,3-butadiyne 5. The photolysis were performed at 185 and 254 nm. The volatile products formed in these reactions were characterized by 1H and 31P NMR. The n-propylphosphine 6 and the isopropylphosphine 7 were the major products observed in the photolysis of PH3 with propene. The allylphosphine 8 was obtained when most of the light was absorbed by propene. This allylphosphine was the main product formed in the photolysis of PH3 in the presence of propadiene; the methylvinylphosphine 10 being not detected in these experiments, the reaction presents a very high regioselectivity. When most of the light was absorbed by propadiene, the propargylphosphine 9 was also observed. The photolysis of PH3 in the presence of propyne led to the E- and Z-1-propenylphosphines 12a,b and small amounts of methylvinylphosphine 10. Even when most of the light was absorbed by propyne, the propargylphosphine 9 was not observed. The Z-1-butene-3-ynylphosphine 13a and a mixture of primary phosphines containing the E-and Z-2-butenylphosphines 14a,b were obtained as major products when 1,3-butadiyne and 1,3-butadiene respectively where photolyzed with PH3. A high regioselectivity was thus observed in the photolysis of PH3 with an alkyne or an allene but alkenes led to mixtures of products. PMID:11541338

Guillemin, J C; Le Serre, S; Lassalle, L

1997-01-01

257

Carbon-yl[4-(2,3-dimethyl-phenyl-amino)pent-3-en-2-onato-?2 N,O](triphenyl-phosphine-?P)rhodium(I)  

PubMed Central

In the title compound, [Rh(C13H16NO)(C18H15P)(CO)], the coordination geometry of the RhI atom is square-planar, formed by the coordinating N and O atoms of the bidentate enaminoketonate ligand, one C atom from the carbonyl group and a P atom from triphenyl­phosphine. The complex displays a 0.591?(3):0.409?(3) ratio disorder of the phenyl unit of the monoanionic N,O-bidentate ligand. Intra­molecular hydrogen bonding is observed between a C—H group of the triphenyl­phosphine unit and the O atom of the enamino­ketonate ligand.

Venter, Gertruida J. S.; Steyl, Gideon; Roodt, Andreas

2009-01-01

258

Passivation of nanocrystalline TiO2 junctions by surface adsorbed phosphinate amphiphiles enhances the photovoltaic performance of dye sensitized solar cells.  

PubMed

We report a new class of molecular insulators that electronically passivate the surface of nanocrystalline titania films for high performance dye sensitized solar cells (DSC). Using electrical impedance measurements we demonstrate that co-adsorption of dineohexyl bis-(3,3-dimethyl-butyl)-phosphinic acid (DINHOP), along with the amphiphilic ruthenium sensitizer Z907Na increased substantially the power output of the cells mainly due to a retardation of interfacial recombination of photo-generated charge carriers. The use of phosphinates as anchoring groups opens up new avenues for modification of the surface by molecular insulators, sensitizers and other electro-active molecules to realize the desired optoelectronic performance of devices based on oxide junctions. PMID:19904428

Wang, Mingkui; Li, Xin; Lin, Hong; Pechy, Peter; Zakeeruddin, Shaik M; Grätzel, Michael

2009-12-01

259

Carbon-yl[4-(2,3-dimethyl-phenyl-amino)pent-3-en-2-onato-?N,O](triphenyl-phosphine-?P)rhodium(I).  

PubMed

In the title compound, [Rh(C(13)H(16)NO)(C(18)H(15)P)(CO)], the coordination geometry of the Rh(I) atom is square-planar, formed by the coordinating N and O atoms of the bidentate enaminoketonate ligand, one C atom from the carbonyl group and a P atom from triphenyl-phosphine. The complex displays a 0.591?(3):0.409?(3) ratio disorder of the phenyl unit of the monoanionic N,O-bidentate ligand. Intra-molecular hydrogen bonding is observed between a C-H group of the triphenyl-phosphine unit and the O atom of the enamino-ketonate ligand. PMID:21578084

Venter, Gertruida J S; Steyl, Gideon; Roodt, Andreas

2009-01-01

260

Study of Electron Donor–Acceptor Complex Formation of o Chloranil With a Series of Phosphine Oxides and Tri n -butyl Phosphate by the Absorption Spectrometric Method  

Microsoft Academic Search

Electron donor–acceptor (EDA) complex formation of o-chloranil with six different phosphine oxides and tri-n-butyl phosphate (TBP) has been studied in CCl 4 solution by the UV-VIS absorption spectrophotometric technique. An absorption band due to a charge–transfer (CT) transition is observed in the visible region. Utilizing the CT transition energy, the electron affinity of o-chloranil in solution has been calculated. Degrees

Sumanta Bhattacharya; Shrabanti Bhattacharya Banerjee; Kalyan Ghosh; Sukalyan Basu; Manas Banerjee

2006-01-01

261

Partitioning of Actinides from High Level Waste of PUREX Origin Using Octylphenyl-N,N'-diisobutylcarbamoylmethyl Phosphine Oxide (CMPO)Based Supported Liquid Membrane  

Microsoft Academic Search

The present studies deal with the application of the supported liquid membrane (SLM) technique for partitioning of actinides from high level waste of PUREX origin. The process uses a solution of octylphenyl-N,N'-diisobutylcarbamoylmethyl phosphine oxide (CMPO) in n-dodecane as a carrier with a polytetrafluoroethylene support and a mixture of citric acid, formic acid, and hydrazine hydrate as the receiving phase. The

A. Ramanujam; P. S. Dhami; V. Gopalakrishnan; N. L. Dudwadkar; R. R. Chitnis; J. N. Mathur

1999-01-01

262

Redox-active phosphines: synthesis and crystal structures of palladium(ii) complexes of a metallaphosphine in two different oxidation states.  

PubMed

The redox-active metallaphosphine [Fe(dppe)(?(5)-C5Me5)(C[triple bond, length as m-dash]C-PPh2)] reacts with [Pd(1,5-cod)Cl2] to give mono- and bis-phosphine coordinated palladium centres as a function of stoichiometry, and these complexes provide a stable redox-active platform which allows reversible one-electron {Fe(ii)?Fe(iii)(+)} oxidations within the palladium coordination sphere. PMID:24710466

Tohmé, Ayham; Labouille, Stéphanie; Roisnel, Thierry; Dorcet, Vincent; Carmichael, Duncan; Paul, Frédéric

2014-05-21

263

Theoretical insights into the effect of amine and phosphine decoration on the photoluminescence of copper(i) and silver(i) coordination polymers.  

PubMed

Coinage metal cyanides (MCN) form photoluminescent 1D coordination polymers. The decoration of these chains with amine and phosphine ligands shifts the wavelength for photoluminescence into the visible region. Density-functional theory (DFT) and time-dependent DFT (TD-DFT) calculations of zigzag and helical models of decorated chains are used to show that the transitions that contribute to the experimental spectra are related to the ?-? excitations previously shown for coinage metal cyanide chains. PMID:24840102

Bayse, Craig A; Harper, Lenora K; Ming, Jasprina L; Pike, Robert D

2014-08-01

264

Ternary ambipolar phosphine oxide hosts based on indirect linkage for highly efficient blue electrophosphorescence: towards high triplet energy, low driving voltage and stable efficiencies.  

PubMed

The effective strategy of indirect linakge for constructing ternary ambipolar phosphine oxide (PO) hosts with the high first triplet energy levels (T(1)) was successfully demonstrated. The interplay between the chromophore, hole and electron transporting moieties was effectively restrained. Both of T(1) as high as 3.0 eV and ambipolar characteristics were perfectly realized, which consequently resulted in the highly efficient blue-emitting phosphorescent organic light-emitting diodes with low driving voltage and stable efficiencies. PMID:22213078

Yu, Donghui; Zhao, Fangchao; Han, Chunmiao; Xu, Hui; Li, Jing; Zhang, Zhen; Deng, Zhaopeng; Ma, Dongge; Yan, Pengfei

2012-01-24

265

Degradation, Cleanup, and Reusability of Octylphenyl- N, N?-diisobutylcarbamoylmethyl Phosphine Oxide (CMPO) during Partitioning of Minor Actinides from High Level Waste (HLW) Solutions  

Microsoft Academic Search

The radiolytic degradation of the extractant mixture 0.2 M octylphenyl-N,N?-diiso-butylcaibamoylmethyl phosphine oxide (CMPO) + 1.2 M tributyl phosphate in n- dodecane [to be utilized for the partitioning of minor actinides from high level waste (HLW) solutions of PUREX origin] has been investigated in contact with 3 M HNO3 or synthetic pressurized heavy water reactors (PHWR)-HLW solution under dynamic conditions. The

J. N. Mathur; M. S. Murali; P. B. Ruikar; M. S. Nagar; A. T. Sipahimalani; A. K. Bauri; A. Banerji

1998-01-01

266

Phosphine-containing Lewis base catalyzed cyclization of benzofuranone type electron-deficient alkenes with allenoates: a facile synthesis of spirocyclic benzofuranones.  

PubMed

A regioselective [3 + 2] cycloaddition of benzofuranone type active olefins with allenoates catalyzed by trivalent phosphines has been developed, which provided an easy access to enriched functionalized spirocyclic benzofuranones. The reactions accommodated a number of benzofuranone type electron-deficient olefins and allenoates to give the desired 3-spirocyclopentane benzofuran-2-ones or 2-spirocyclopentane benzofuran-3-ones with moderate to excellent yields (up to 99%) and moderate to good regioselectivities (up to 11:1). PMID:23344672

Li, Xin; Wang, Feng; Dong, Nan; Cheng, Jin-Pei

2013-03-01

267

Synthesis of new rhodium complexes with a hemilabile nitrogen-containing bis(phosphinite) or bis(phosphine) ligand. Application to hydroformylation of styrene  

Microsoft Academic Search

Two new cationic rhodium(I) complexes with a hemilabile nitrogen-containing bis(phosphinite) or bis(phosphine) ligand have been prepared. 31P-NMR studies provide evidence that the ligands are coordinated to the metal in P,P-bidentate mode, whereas for the bis(phoshine)-based ligand, a P,N,P-tridentate mode is also possible to be found at low temperatures. The complexes were applied to the hydroformylation of styrene and displayed a

Ioannis D. Kostas

2001-01-01

268

Synthesis of 1-[bis(trifluoromethyl)phosphine]-1'-oxazolinylferrocene ligands and their application in regio- and enantioselective Pd-catalyzed allylic alkylation of monosubstituted allyl substrates  

PubMed Central

Summary A class of novel, easily accessible and air-stable 1-[bis(trifluoromethyl)phosphine]-1’-oxazolinylferrocene ligands has been synthesized from ferrocene. It became apparent that these ligands can be used in the regio- and enantioselective Pd-catalyzed allylic alkylation of monosubstituted allyl substrates in a highly efficient manner. Excellent regio- and enantioselectivity could be obtained for a wide range of substrates.

Lai, Zeng-Wei; Yang, Rong-Fei; Ye, Ke-Yin

2014-01-01

269

Different in vitro and in vivo profiles of substituted 3-aminopropylphosphinate and 3-aminopropyl(methyl)phosphinate GABAB receptor agonists as inhibitors of transient lower oesophageal sphincter relaxation  

PubMed Central

BACKGROUND AND PURPOSE Gastro-oesophageal reflux is predominantly caused by transient lower oesophageal sphincter relaxation (TLOSR) and GABAB receptor stimulation inhibits TLOSR. Lesogaberan produces fewer CNS side effects than baclofen, which has been attributed to its affinity for the GABA transporter (GAT), the action of which limits stimulation of central GABAB receptors. To understand the structure–activity relationship for analogues of lesogaberan (3-aminopropylphosphinic acids), and corresponding 3-aminopropyl(methyl)phosphinic acids, we have compared representatives of these classes in different in vitro and in vivo models. EXPERIMENTAL APPROACH The compounds were characterized in terms of GABAB agonism in vitro. Binding to GATs and cellular uptake was done using rat brain membranes and slices respectively. TLOSR was measured in dogs, and CNS side effects were evaluated as hypothermia in mice and rats. KEY RESULTS 3-Aminopropylphosphinic acids inhibited TLOSR with a superior therapeutic index compared to 3-aminopropyl(methyl)phosphinic acids. This difference was most likely due to differential GAT-mediated uptake into brain cells of the former but not latter. In agreement, 3-aminopropyl(methyl)phosphinic acids were much more potent in producing hypothermia in rats even when administered i.c.v. CONCLUSIONS AND IMPLICATIONS An enhanced therapeutic window for 3-aminopropylphosphinic acids compared with 3-aminopropyl(methyl)phosphinic acids with respect to inhibition of TLOSR was observed and is probably mechanistically linked to neural cell uptake of the former but not latter group of compounds. These findings offer a platform for discovery of new GABAB receptor agonists for the treatment of reflux disease and other conditions where selective peripheral GABAB receptor agonism may afford therapeutic effects.

Lehmann, A; Antonsson, M; Aurell-Holmberg, A; Blackshaw, LA; Branden, L; Elebring, T; Jensen, J; Karrberg, L; Mattsson, JP; Nilsson, K; Oja, SS; Saransaari, P; von Unge, S

2012-01-01

270

Phosphine-Olefin Ligands Based on a Planar-Chiral (?-Arene)chromium Scaffold: Design, Synthesis, and Application in Asymmetric Catalysis.  

PubMed

The NMR and X-ray crystallographic studies clarified that planar-chiral alkenylene-bridged (phosphino-?-arene)(phosphine)chromium complexes 3 were capable of coordinating to a rhodium(I) cation in a bidentate fashion at the (?-arene)-bound phosphorus atom and at the olefin moiety. The P-olefin chelate coordination of 3 constructs the effective chiral environment at the metal center, and thus, these rhodium complexes display high performances in various rhodium-catalyzed asymmetric 1,4- and 1,2-addition reactions with arylboron nucleophiles. The control experiments demonstrated that the (?(2)-olefin)-Rh interaction as well as the bridging structure in 3 played the pivotal roles in the high enantioselectivity of the Rh-catalyzed asymmetric reactions. To enhance the synthetic utilities of these phosphine-olefin ligands, an enantiospecific and scalable synthetic method was developed. The novel synthetic method is flexible in terms of the substituent variation, and a library of the planar-chiral (arene)chromium-based phosphine-olefin ligands was established by the combinatorial approach. Among the newly prepared ligand library, compound 3g, which is with a bis(3,5-dimethylphenyl)phosphino group on the ?(6)-arene ring, was found to be a far better chiral ligand in the rhodium-catalyzed asymmetric reactions showing excellent enantioselectivity and high yields. PMID:24932944

Ogasawara, Masamichi; Tseng, Ya-Yi; Arae, Sachie; Morita, Tomotaka; Nakaya, Takeshi; Wu, Wei-Yi; Takahashi, Tamotsu; Kamikawa, Ken

2014-07-01

271

Synthetic, structural, NMR, and computational study of a geminally bis(peri-substituted) tridentate phosphine and its chalcogenides and transition-metal complexes.  

PubMed

Coupling of two acenaphthene backbones through a phosphorus atom in a geminal fashion gives the first geminally bis(peri-substituted) tridentate phosphine 1. The rigid nature of the aromatic backbone and overall crowding of the molecule result in a rather inflexible ligand, with the three phosphorus atoms forming a relatively compact triangular cluster. Phosphine 1 displays restricted dynamics on an NMR time scale, which leads to the anisochronicity of all three phosphorus nuclei at low temperatures. Strained bis- and tris(sulfides) 2 and 3 and the bis(selenide) 4 have been isolated from the reaction of 1 with sulfur and selenium, respectively. These chalcogeno derivatives display pronounced in-plane and out-of-plane distortions of the aromatic backbones, indicating the limits of their angular distortions. In addition, we report metal complexes with tetrahedral [(1)Cu(MeCN)][BF4] (5), square planar [(1)PtCl][Cl] (6), trigonal bipyramidal [(1)FeCl2] (7), and octahedral fac-[(1)Mo(CO)3] (8) geometries. In all of these complexes the tris(phosphine) backbone is distorted, however to a significantly smaller extent than that in the mentioned chalcogenides 2-4. Complexes 5 and 8 show fluxionality in (31)P and (1)H NMR. All new compounds 1-8 were fully characterized, and their crystal structures are reported. Conclusions from dynamic NMR observations were augmented by DFT calculations. PMID:23534381

Ray, Matthew J; Randall, Rebecca A M; Arachchige, Kasun S Athukorala; Slawin, Alexandra M Z; Bühl, Michael; Lebl, Tomas; Kilian, Petr

2013-04-15

272

Carbonyl[4-(2,6-dimethyl-phenyl-amino)pent-3-en-2-onato-?2 N,O](triphenyl-phosphine-?P)rhodium(I) acetone hemi-solvate  

PubMed Central

In the title compound, [Rh(C13H16NO)(C18H15P)(CO)]·0.5C3H6O, the Rh atom exhibits a square-planar coordination geometry, being coordinated by the N and O atoms of the bidentate ?-diketonato ligand, a P atom from the triphenyl­phosphine unit and a C atom from the carbonyl group. The asymmetric unit also contains a disordered half-mol­ecule, lying about an inversion center, of the acetone solvate. Inter­molecular C—H?O hydrogen bonds are observed between a C—H group of the triphenyl­phosphine unit and a carbonyl O atom and between the methyl group of the enamino­ketonato backbone and the solvent O atom. In addition, an intra­molecular inter­action is observed between a C—H group of the triphenyl­phosphine unit and the O atom of the enamino­ketonato ligand.

Venter, Gertruida J. S.; Steyl, Gideon; Roodt, Andreas

2009-01-01

273

Mixed-ligand chelate extraction of lanthanides with 1-phenyl-3-methyl-4-(trifluoroacetyl)-5-pyrazolone and some phosphine oxide compounds  

SciTech Connect

Mixed-ligand chelate extraction of lanthanides (Ln) such as La, Pr, Eu, Ho, and Yb into chloroform with 1-phenyl-3-methyl-4-(trifluoroacetyl)-5-pyrazolone (HPMTFP) and with one of three phosphine oxide compounds is studied. The phosphine oxide compounds employed in the present work are tri-n-octylphosphine oxide (TOPO), n-octylphenyl(N,N-diisobutylcarbamoylmethyl)phosphine oxide (CMPO), and methylenebis(diphenylphosphine oxide) (MBDPO). Lanthanide ions are found to be extracted from a 0.1 M sodium perchlorate medium as Ln(PMTFP)/sub 3/(TOPO)/sub 2/ and Ln(PMTFP)/sub 3/(CMPO), respectively. In the extraction of lanthanides with the mixture of HPMTFP and MBDPO, the extracted species are found to be Ln(PMTFP)/sub 3/(MBDPO) or Ln(PMTFP)/sub 2/(ClO/sub 4/)(MBDPO)/sub 2/ in the absence or presence of sodium perchlorate, respectively. The extraction constants of these systems do not increase monotonically with atomic number but have a maximum at Eu or Ho. 11 references, 4 tables.

Umetani, S.; Freiser, H.

1987-09-23

274

The quaternisation reaction of phosphines and amines in aliphatic alcohols. A similarity analysis using the isokinetic, isosolvent and isoselective relationships.  

PubMed

Accurate second-order rate constants were measured at 5 K intervals in the temperature range 298.15-328.15 K for the quaternisation reaction of triethylphosphine with iodoethane in methanol, ethanol, propan-1-ol and butan-1-ol. These data are complemented previously reported rate constants for the quaternisation reaction of triethylamine with iodoethane in the same solvents and at similar temperatures. Each of these two reaction series is analysed in terms of the isokinetic relationship (IKR) with respect to solvent variation and of the isosolvent relationship (ISoR) with respect to temperature variation, using in the latter case five different empirical solvent scales. Statistically validated IKR and ISoR have been found for both reaction series. The resulting isokinetic temperatures of 347 K (phosphine series) and of 730 K (amine series) are discussed in terms of Linert's theory of the isokinetic relationship. The best ISoR correlation is obtained using the Dimroth-Reichardt E(T)(N) solvent scale for the phosphine series and the Kamlet-Taft alpha(KT) solvent scale for the amine series. It is demonstrated that no real solvent can be envisaged as having the characteristics of an isokinetic solvent. The selectivity of the nucleophiles triethylphosphine and triethylamine in the attack on iodoethane is examined by treating together both reaction series in terms of the isoselective relationship (ISeR). The isoselective temperature with respect to solvent is found to be 289 K, which is close to the value of 302 K predicted by Exner and Giese's formula on the basis of the individual isokinetic temperatures. A novel ISeR analysis with respect to temperature is performed. It reveals that the alpha(KT) scale is the most appropriate solvent scale for describing this selectivity series, and that it is feasible to find an isoselective solvent. A new equation is developed for predicting the isoselective solvent parameter from individual isosolvent parameters and is shown to yield realistic values. The present similarity analysis shows that there are significant differences between the courses of these quaternisation reactions. On the basis of the experimentally determined isoparameter values, in liquid alcohols as solvent it is proposed that the reaction between triethylphosphine and iodoethane follows a classic bimolecular nucleophilic substitution pathway, whereas the desolvation of triethylamine molecules has to be taken into account to describe the mechanism of the original Menshutkin reaction. PMID:15105923

Pinheiro, Lidia M V; Calado, António R T; Reis, João Carlos R

2004-05-01

275

Joint Recovery of f-Elements Using Solvent Based on Carbamoyl-phosphine Oxides Heading Toward ORGA-Process  

SciTech Connect

Development of the recovery system which allows realizing joint recovery of all the actinides from the HLW is one of the relevant questions in radiochemistry. Carbamoyl-phosphine oxides (CMPO) were proposed and studied as extractant for rare-earth and transplutonium elements (RE and TPE) recovery from HLW with high acidity, for example TRUEX- and SETFICS-process. Organic system CMPO with TBP in kerosene is usually used as a solvent. However, low solubility of actinide adducts with CMPO results in third phase formation when the actinides concentration in organic phase is high. Application of fluorinated polar diluents increases the solubility of CMPO adducts with actinides in organic phase. It was shown that solvent based on carbamoyl-phosphonate in fluorinated polar diluents allows to recover both uranium and minor actinides concurrently, and there was no precipitation or third phase formation even at high uranium concentration in organic phase. The f-elements joint recovery process based on this solvent was proposed. Solvent containing octyl-phenyl-N,N-di-isobutyl-carbamoyl-methylene-phosphine oxide (O{phi}D[iB]CMPO) in polar diluent meta-nitro-benzo-trifluoride (fluoro-pole-732) was screened out for these studies. And, combined use of them with TBP modifier allows to provide uranium and europium (americium) high recovery characteristics concurrently with an opportunity of attainment of f-elements high concentration in organic phase. As it was indicated, precipitates or third phase was absent even when uranium content in organic phase was 100 g/l. Recovery efficiency to europium remained sufficiently high for its effective recovery. Organic phase saturation about 100% from theoretical attains in europium recovery with this system. Increasing of (O{phi}D[iB]CMPO) concentration in recovery system from 0.2 to 0.8 M results in europium content increasing in organic phase, but no third phase formation is observed. The highest possible europium content in organic phase is about 30 g/l for system with 0.2 M O{phi}D[iB]CMPO and 60- 65 g/l for system with 0.8 M O{phi}D[iB]CMPO. Proposed mixture solvent can be used in joint recovery of all f-elements directly from the dissolver solution of nuclear spent fuel - ORGA-process (abbreviation of Organo-phosphoryl-fluoro-pole solvent for Recovery of Group of Actinides). The ORGA flowsheet is expected to be highly proliferation-resistant, because TRU group and U will separately be recovered by proposed aqueous, salt-free complexants. (authors)

Ozawa, M. [4002 Narita-cho, Japan Atomic Energy Agency, O-arai-machi, Ibaraki-ken, Post No. 311-1393 (Japan); Babain, V.; Shadrin, A.; Strelkov, S.; Kiseleva, R.; Murzin, A. [2nd Murinsky Avenue, RPA V.G.Khlopin Radium Institute, 194021, Saint-Petersburg, 28 (Russian Federation)

2007-07-01

276

Carboxylatodirhodium(II) complexes with orthometallated tris( p-methoxyphenyl)phosphine and their reactions with pyrazole and imidazole  

Microsoft Academic Search

Exchange reactions of the acetato bridges in [cis-Rh2(?-OAc)2{?-(C6H3-4-OMe)P(C6H4-4-OMe)2}2(HOAc)2] ([1(HOAc)2]) for trifluoroacetato and propionato bridges give new dirhodium(II) complexes with two orthometallated molecules of tris(p-methoxyphenyl)phosphine (PMP): [cis-Rh2(?-O2CCF3)2{?-(C6H3-4-OMe)P(C6H4-4-OMe)2}2(HO2CCF3)2] ([2(HO2CCF3)2]) and [cis-Rh2(?-O2CCH2CH3)2{?-(C6H3-4-OMe)P(C6H4-4-OMe)2}2(HO2CCH2CH3)2]·HO2CCH2CH3 ([3(HO2CEt)2]·HO2CEt), respectively. X-ray structures of the complexes [2(H2O)(PrOH)]·PrOH and [3(HO2CEt)2]·HO2CEt, as well as of pyrazole adducts [2(C3H4N2)2] and [3(C3H4N2)2] have been determined. The Rh–Rh distances in [2(C3H4N2)2] and [3(C3H4N2)2] are a

Rados?aw Starosta; Florian P. Pruchnik; Zbigniew Ciunik

2006-01-01

277

Gold(I)Gold(III)-4,4?-bpy-phosphine complexes: Synthesis and multinuclear NMR study  

Microsoft Academic Search

Silver assisted de-bromination gives [Au2(dppm\\/dppe\\/dppa) (OTf)2], which on reaction with 4,4?-bpy and gold(I) phosphines in CH2Cl2 medium, by the self assembly technique, leads to [(PPh3)Au(4,4?-bpy)Au(PPh3)], (1a–1d,2), [{Au2(dppm\\/dppe\\/dppa)}{(4,4-bpy)Au(PPh3)}2](NO3)4, (3), [{Au4(dppm\\/dppe\\/dppa)2(4,4-bpy)2}](OTf)4, \\u000a (4), [{(PPh3)AuI(4,4?-bpy)}2AuIII(C6F5\\/Mes)](NO3)3, (5) [dppm\\/dppe\\/dppa =diphenyl phosphino-methane(a), –ethane(b), ammine(c), C6F5\\/Mes pentafluorophenyl\\/mesitylene]. The maximum molecular peak of the corresponding molecule is observed in the ESI mass spectrum.\\u000a Ir spectra of the complexes show

Prithwiraj Byabartta

2007-01-01

278

Imino-phosphine palladium(II) and platinum(II) complexes: synthesis, molecular structures and evaluation as antitumor agents.  

PubMed

The imino-phosphine ligands L1 and L2 were prepared via condensation reaction of 2-(diphenylphosphino)benzaldehyde with substituted anilines and obtained in very good yields. An equimolar reaction of L1 and L2 with either PdCl2(cod) or PtCl2(cod) gave new palladium(II) and platinum(II) complexes 1-4. The compounds were characterized by elemental analysis, IR, (1)H and (31)P NMR spectroscopy. The molecular structures of 2, 3 and 4 were confirmed by X-ray crystallography. All the three molecular structures crystallized in monoclinic C2/c space system. The coordination geometry around the palladium and platinum atoms in respective structures exhibited distorted square planar geometry at the metal centers. The complexes were evaluated in vitro for their cytotoxic activity against human breast (MCF-7) and human colon (HT-29) cancer cells, and they exhibited growth inhibitory activities and selectivity that were superior to the standard compound cisplatin. PMID:24099695

Motswainyana, William M; Onani, Martin O; Madiehe, Abram M; Saibu, Morounke; Thovhogi, Ntevheleni; Lalancette, Roger A

2013-12-01

279

Chemical behavior and in vitro activity of mixed phosphine gold(I) compounds on melanoma cell lines.  

PubMed

(31)P nuclear magnetic resonance and electrospray ionization-mass spectrometry studies on the melanoma cytotoxic chlorotriphenylphosphine-1,3-bis(diphenylphosphino)propanegold(I), [Au(DPPP)(PPh 3)Cl], show partial decomposition that includes the novel dinuclear cation [Au 2(DPPP) 2Cl] (+); its structure was calculated by using the density functional theory (DFT). Unexpectedly, by using the diphosphine ligand 1,2-bis(diphenylphosphino)ethane (DIPHOS), [{AuCl(PPh 3)} 2(mu 2-DIPHOS)] was obtained. Its X-ray crystal structure shows a unique triangular coordination sphere in contrast to the T-shaped geometry of related Au(I)-DIPHOS compounds. Its cytotoxic activity in JR8, SK-Mel-5, and 2/60 melanoma cell lines is dose-dependent and lower than that of [Au(DPPP)(PPh 3)Cl] because of its nonchelating nature. An in vitro study of the effect of both Au compounds on the B16V melanoma cell line gives credence to this structure-activity relationship. IC 50 indicates that both Au species are 10 times more active in B16V than in JR8, SK-Mel-5, and 2/60. Oxidation of [Au(DPPP)(PPh 3)Cl] toward Au(III) compounds and phosphine-oxides is observed upon reaction with hypochlorite in water/dimethyl sulfoxide solution, mimicking endogenous hypochlorite. A related reaction involving the formation of [AuCl 4] (-) is thermodynamically feasible according to DFT calculations. PMID:18307291

Caruso, Francesco; Pettinari, Claudio; Paduano, Francesco; Villa, Raffaella; Marchetti, Fabio; Monti, Elena; Rossi, Miriam

2008-03-27

280

Syntheses and molecular structure of some Rh and Ru complexes with the chelating diphenyl (2-pyridyl)phosphine ligand.  

PubMed

The rhodium(III) complex mer,cis-[RhCl3(PPh2py-P,N)(PPh2py-P)] (1) (PPh2py = diphenyl (2-pyridyl)phosphine) has been prepared from RhCl3 x 3H2O and PPh2py and converted to the trans,cis-[RhCl2(PPh2py-P,N)2]PF6 (2) in acetone solution by treatment with Ag+ and PF6(-). Ruthenium(III) and ruthenium(II) compounds with PPh2py, mer,cis-[RuCl3(PPh2py-P,N)(PPh2py-P)] (3) and mer-[RuCl(PPh2py-P,N)2(PPh2py-P)]Cl (5) have been obtained from DMSO precursor complexes. In a chloroform solution, complex (5) isomerizes to fac-[RuCl(PPh2py-P,N)2(PPh2py-P)]Cl (fac-5). All compounds have been characterized by MS, UV-vis, IR, and 1H and 31P{1H} NMR spectroscopy, and the Ru(III) compound has been characterized by EPR spectroscopy as well. The crystal structures of 1, 2, 3, and fac-5 have been determined. In all compounds under investigation, at least one pyridylphosphine acts as a chelate ligand. The 31P chemical shifts for chelating PPh2py-P,N depend on the Ru-P bond lengths. PMID:16602796

Wajda-Hermanowicz, Katarzyna; Ciunik, Zbigniew; Kochel, Andrzej

2006-04-17

281

Theoretical study of reaction pathways for the rhodium phosphine-catalysed borylation of C-H bonds with pinacolborane.  

PubMed

The reaction mechanism of the rhodium-phosphine catalysed borylation of methyl-substituted arenes using pinacolborane (HBpin) has been investigated theoretically using DFT calculations at the B3PW91 level. Factors affecting selectivity for benzylic vs. aromatic C-H bond activation have been examined. It was found that [Rh(PR3)2(H)] is the active species which oxidatively adds the C-H bond leading to an eta3-benzyl complex which is the key to determining the unusual benzylic regioselectivity observed experimentally for this catalyst system. Subsequent reaction with HBpin leads to a [Rh(PR3)2(eta3-benzyl)(H)(Bpin)] complex from which B-C reductive elimination provides product and regenerates the catalyst. The electrophilic nature of the boryl ligand assists in the reductive elimination process. In contrast to Ir(L)2(boryl)3-based catalysts, for which Ir(III)-Ir(V) cycles have been proposed, the Rh(I)-Rh(III) cycle is operating with the system addressed herein. PMID:15252604

Lam, Wai Han; Lam, King Chung; Lin, Zhenyang; Shimada, Shigeru; Perutz, Robin N; Marder, Todd B

2004-05-21

282

Phosphine oxide derivatives as hosts for blue phosphors: A joint theoretical and experimental study of their electronic structure  

SciTech Connect

We report on a joint theoretical and experimental investigation of the electronic structure of a series of bis(diphenylphosphine oxide) derivatives containing a central aromatic core with high triplet energy. Such molecules can serve as host material in the emissive layer of blue electro-phosphorescent organic devices. The aromatic cores considered in the theoretical study consist of biphenyl, fluorene, dibenzofuran, dibenzothiophene, dibenzothiophenesulfone or carbazole, linked to the two phosphoryl groups in either para or meta positions. With respect to the isolated core molecules, it is found that addition of the diphenylphosphine oxide moieties has hardly any impact on the core geometry and only slightly reduces the energy of the lowest triplet state (by at most ~0.2 eV). However, the diphenylphosphine oxide functionalities significantly impact the ionization potential and electron affinity values, in a way that is different for para and meta substitutions. Excellent comparison is obtained between the experimental UPS and IPES spectra of the para biphenyl and meta dibenzothiophene and dibenzothiophenesulfone compounds and the simulated spectra. In general, the phosphine oxide derivatives present triplet energies that are calculated to be at least 0.2 eV higher than those of currently widely used blue phosphorescent emitters.

Kim, Dongwook; Salman, Seyhan; Coropceanu, Veaceslav; Salomon, Eric; Padmaperuma, Asanga B.; Sapochak, Linda S.; Kahn, Antoine; Bredas, Jean-Luc

2010-01-12

283

Identification of phosphinate dipeptide analog inhibitors directed against the Plasmodium falciparum M17 leucine aminopeptidase as lead antimalarial compounds.  

PubMed

Previous studies have pinpointed the M17 leucyl aminopeptidase of Plasmodium falciparum (PfLAP) as a target for the development of new antimalarials. This metallo-exopeptidase functions in the terminal stages of hemoglobin digestion and is inhibited by bestatin, a natural analog of Phe-Leu. By screening novel phosphinate dipeptide analogues for inhibitory activity against recombinant PfLAP, we have discovered two compounds, 4 (hPheP[CH2]Phe) and 5 (hPheP[CH2]Tyr), with inhibitory constants better than bestatin. These compounds are fast, tight-binding inhibitors that make improved contacts within the active site of PfLAP. Both compounds inhibit the growth of P. falciparum in vitro, exhibiting IC50 values against the chloroquine-resistant clone Dd2 of 20-40 and 12-23 muM, respectively. While bestatin exhibited some in vivo activity against Plasmodium chabaudi chabaudi, compound 4 reduced parasite burden by 92%. These studies establish the PfLAP as a prime target for the development of antimalarial drugs and provide important new lead compounds. PMID:17960925

Skinner-Adams, Tina S; Lowther, Jonathan; Teuscher, Franka; Stack, Colin M; Grembecka, Jolanta; Mucha, Artur; Kafarski, Pawel; Trenholme, Katharine R; Dalton, John P; Gardiner, Donald L

2007-11-29

284

Synthesis, spectroscopic and structural characterization of tertiary phosphine tellurium dihalides Et3PTeX2(X = Cl, Br, I).  

PubMed

The reactions of triethylphosphine telluride with SO2Cl2 or I2 produced the first structurally characterized tellurium-containing tertiary phosphine chalcogen dihalides, Et3PTeCl2 and Et3PTeI2, respectively, in good yields. The corresponding dibromide, Et3PTeBr2, was obtained by an in situ reaction between Et3PTeCl2 and two equivalents of Me3SiBr. This series of compounds has been characterized in the solid state by X-ray structural analyses and in solution by multinuclear NMR spectra. The structures of Et3PTeX2(X = Cl, Br, I) all show a T-shaped geometry around tellurium with weak Te...halogen interactions giving rise to centrosymmetric dimers. NMR data indicate that Et3PTeI2 exhibits the weakest P-Te bond in solution. The ionic complexes, [(Et3PO)2H]2[Te2I6] and [(Et3PO)2H]2[TeI4], were isolated from THF solutions of Et3PTeI2 and characterized by X-ray structural determinations. PMID:16896456

Konu, Jari; Chivers, Tristram

2006-08-28

285

Separation of phenols from dilute aqueous solution by use of tri-n-octyl phosphine oxide as extractant  

SciTech Connect

Trioctyl phosphine oxide (TOPO) is examined as an extractant for phenol and other phenolic compounds. Equilibrium distribution coefficients have been measured for extraction of phenol, dihydroxybenzenes, and trihydroxybenzenes by solvents composed of TOPO in various diluents. Results are interpreted in terms of a model based upon complexation stoichiometry, allowing for solvation of uncomplexed solute as well. TOPO is a strong complexant for all the phenolic solutes studied. The nature of the diluent has a significant effect upon distribution coefficients, and in the case of an alcohol diluent reduces the distribution coefficient for phenol considerably. The degree of complexation remains appreciable at temperatures which would be used for regeneration of phenol by distillation. This makes it necessary to use a diluent boiling at least 70/sup 0/C to 80/sup 0/C higher than the boiling point of phenol, which is 182/sup 0/C. Regeneration studies are reported for isobutyl heptyl ketone, dimethylnaphthalene, and a mixture of dimethylnaphthlene and n-octadecane as diluents. Extraction with TOPO will be most worthy of consideration for feed concentrations of phenol equal to 3000 ppM or less, or for extraction of di- and tri-hydroxybenzenes.

MacGlashan, J.D.; Bixby, J.L.; King, C.J.

1985-01-01

286

Photocatalytic properties of new cyclopentadienyl and indenyl rhodium(I) carbonyl complexes with water-soluble 1,3,5-triaza-7-phosphaadamantane (PTA) and tris(2-cyanoethyl)phosphine  

Microsoft Academic Search

Reactions of [(?5-R)Rh(CO)2] (R = cp, ind) with water-soluble phosphines (L = 1,3,5-triaza-7-phosphaadamantane and tris(2-cyanoethyl)phosphine) give the new rhodium(I) complexes of the types [Rh(?5-cp)(CO)(PTA)] (1), [Rh(?5-cp)(CO)(P(CH2CH2CN)3)] (2), [Rh(?5-ind)(CO)(PTA)] (3) and [Rh(?5-ind)(CO)(P(CH2CH2CN)3)] (4) in isolated yields of 52–75%. All these compounds have been fully characterized by IR, 1H, 31P{1H} and 13C{1H} NMR, FAB-MS spectroscopies and elemental analyses. Reactivity for the substitution of phosphine is greater

Piotr Smole?ski

2011-01-01

287

Reactivity of the triruthenium ortho-metalated cluster [Ru 3(CO) 9{? 3-? 1,? 1,? 2PhP(C 6H 4)CH 2PPh}] with tri(2-thienyl)phosphine and tri(2-furyl)phosphine: Formation of 1,3-diphenyl-2,3-dihydro-1H-1,3-benzodiphosphine complexes via phosphorus–carbon bond formation  

Microsoft Academic Search

Reaction of [Ru3(CO)9{?3-?1,?1,?2-PhP(C6H4)CH2PPh}] (1) with tri(2-thienyl)phosphine (PTh3) in refluxing THF afforded [Ru3(CO)9(PTh3)(?-dpbm)] (3) {dpbm=PhP(C6H4)(CH2)PPh} and [Ru3(CO)6(?-CO)2{?-?1,?1-PTh2(C4H2S)}{?3-?1,?2-Ph2PCH2PPh}] (5) in 18% and 12% yields, respectively, while a similar reaction with tri(2-furyl)phosphine (PFu3) gave [Ru3(CO)9(PFu3)(?-dpbm)] (4) and [Ru3(CO)7(?-?1,?2-C4H3O)(?-PFu2){?3-?1,?1,?2-PhP(C6H4)CH2PPh}] (6) in 24% and 27% yields, respectively. Compounds 2 and 4 are phosphine adducts of 1 in which the diphosphine ligand is transformed into 1,3-diphenyl-2,3-dihydro-1H-1,3-benzodiphosphine

Shishir Ghosh; Shahed Rana; Derek A. Tocher; Graeme Hogarth; Ebbe Nordlander; Shariff E. Kabir

2009-01-01

288

Molecular Control of the Nanoscale: Effect of Phosphine–Chalcogenide Reactivity on CdS–CdSe Nanocrystal Composition and Morphology  

SciTech Connect

We demonstrate molecular control of nanoscale composition, alloying, and morphology (aspect ratio) in CdS–CdSe nanocrystal dots and rods by modulating the chemical reactivity of phosphine–chalcogenide precursors. Specific molecular precursors studied were sulfides and selenides of triphenylphosphite (TPP), diphenylpropylphosphine (DPP), tributylphosphine (TBP), trioctylphosphine (TOP), and hexaethylphosphorustriamide (HPT). Computational (DFT), NMR (31P and 77Se), and high-temperature crossover studies unambiguously confirm a chemical bonding interaction between phosphorus and chalcogen atoms in all precursors. Phosphine–chalcogenide precursor reactivity increases in the order: TPPE < DPPE < TBPE < TOPE < HPTE (E = S, Se). For a given phosphine, the selenide is always more reactive than the sulfide. CdS1–xSex quantum dots were synthesized via single injection of a R3PS–R3PSe mixture to cadmium oleate at 250 °C. X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV/Vis and PL optical spectroscopy reveal that relative R3PS and R3PSe reactivity dictates CdS1–xSex dot chalcogen content and the extent of radial alloying (alloys vs core/shells). CdS, CdSe, and CdS1–xSex quantum rods were synthesized by injection of a single R3PE (E = S or Se) precursor or a R3PS–R3PSe mixture to cadmium–phosphonate at 320 or 250 °C. XRD and TEM reveal that the length-to-diameter aspect ratio of CdS and CdSe nanorods is inversely proportional to R3PE precursor reactivity. Purposely matching or mismatching R3PS–R3PSe precursor reactivity leads to CdS1–xSex nanorods without or with axial composition gradients, respectively. We expect these observations will lead to scalable and highly predictable “bottom-up” programmed syntheses of finely heterostructured nanomaterials with well-defined architectures and properties that are tailored for precise applications.

Ruberu, T. Purnima A.; Albright, Haley R.; Callis, Brandon; Ward, Brittney; Cisneros, Joana; Fan, Hua-Jun; Vela, Javier

2012-04-22

289

Rhodium-catalyzed dehydrocoupling of fluorinated phosphine-borane adducts: synthesis, characterization, and properties of cyclic and polymeric phosphinoboranes with electron-withdrawing substituents at phosphorus.  

PubMed

The dehydrocoupling of the fluorinated secondary phosphine-borane adduct R2PH.BH3 (R = p-CF3C6H4) at 60 degrees C is catalyzed by the rhodium complex [{Rh(mu-Cl)(1,5-cod)}2] to give the four-membered chain R2PH-BH2-R2P-BH3. A mixture of the cyclic trimer [R2P-BH2]3 and tetramer [R2P-BH2]4 was obtained from the same reaction at a more elevated temperature of 100 degrees C. The analogous rhodium-catalyzed dehydrocoupling of the primary phosphine-borane adduct RPH2.BH3 at 60 degrees C gave the high molecular weight polyphosphinoborane polymer [RPH-BH2]n (Mw = 56,170, PDI = 1.67). The molecular weight was investigated by gel permeation chromatography and the compound characterized by multinuclear NMR spectroscopy. Interestingly, the electron-withdrawing fluorinated aryl substituents have an important influence on the reactivity as the dehydrocoupling process occurred efficiently at the mildest temperatures observed for phosphine-borane adducts to date. Thin films of polymeric [RPH-BH2]n (R = p-CF3C6H4) have also been shown to function as effective negative-tone resists towards electron beam (e-beam) lithography (EBL). The resultant patterned bars were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM) and time-of-flight secondary ion mass spectrometry (TOF-SIMS). PMID:15900547

Clark, Timothy J; Rodezno, José M; Clendenning, Scott B; Aouba, Stephane; Brodersen, Peter M; Lough, Alan J; Ruda, Harry E; Manners, Ian

2005-07-18

290

Recent Progress on the Photonic Properties of Conjugated Organometallic Polymers Built Upon the trans-Bis(para-ethynylbenzene)bis(phosphine)platinum(II) Chromophore and Related Derivatives.  

PubMed

This review article surveys the electronic and photophysical properties of conjugated organometallic polymers built upon the title compound and its related derivatives focussing primarily on systems investigated in our laboratories. The general structure of the polymers is (trans-bis(para-ethynylbenzene)bis(phosphine)platinum(II)-G)(n) where G is a conjugated group such as thiophene, fluorene, carbazole, substituted silole, quinone derivative, and metalloporphyrin residue, or a non-conjugated main-group moiety. Systems based on substituted phenylene units and other related fused rings are also discussed. The phosphine ligands are generally triethyl- or tri-n-butylphosphine groups. These trans-platinum(II) polymers and the corresponding model compounds are compared to the corresponding ortho-derivatives in the quinone series, and the newly prepared paracyclophane-containing polymers. For the porphyrin series, a comparison of fully conjugated oligomers exhibiting the general structure (trans-bis(para-ethynyl(zinc(porphyrin)))bis(phosphine)platinum(II))(n) (i.e., the C(6) H(4) group is absent from the main chain) will be made. This contribution also includes a description of the properties of the mononuclear chromophore itself, properties that define those of the polymers. Potential applications with regard to electronic and optical devices will be highlighted. These soluble and stable materials feature both the processing advantages of polymers and the functionality provided by the presence of metal centers. These multifunctional organometallic polyyne polymers exhibit convenient structural variability as well as optical and electronic properties, which renders them important for use in different research domains as chemical sensors and sensor protectors, as converters for light/electricity signals, and as patternable precursors to magnetic metal alloy nanoparticles. PMID:21590959

Wong, Wai-Yeung; Harvey, Pierre D

2010-04-20

291

Preparation, crystal structures and spectroscopic properties of novel [M IIICl 3 ? n (P) 3 + n ] n+ (M = Co, Rh; n = 0, 1, 2 or 3) series of complexes containing tripodal tridentate phosphine, 1,1,1-tris(dimethylphosphinomethyl)ethane  

Microsoft Academic Search

Cobalt(III) and rhodium(III) complexes of the series of [MIIICl3?n(P)3+n]n+ (M=Co or Rh; n=0, 1, 2 or 3) have been prepared with the use of 1,1,1-tris(dimethylphosphinomethyl)ethane (tdmme) and mono- or didentate phosphines. The single-crystal X-ray analyses of both series of complexes revealed that the M–P and M–Cl bond lengths were dependent primarily on the strong trans influence of the phosphines, and

Takayoshi Suzuki; Toshiaki Tsukuda; Masakazu Kiki; Sumio Kaizaki; Kiyoshi Isobe; Hideo D. Takagi; Kazuo Kashiwabara

2005-01-01

292

Solid-state sup 31 P NMR, far-IR, and structural studies on two-coordinate (tris(2,4,6-trimethoxyphenyl)phosphine)copper(I) chloride and bromide  

Microsoft Academic Search

The reactions of acetonitrile solutions of copper(I) chloride, CuCl, and copper(I) bromide, CuBr, with the sterically hindered, highly basic tertiary phosphine ligand tris(2,4,6-trimethoxyphenyl)phosphine ({equivalent to}P(2,4,6)â) have been shown to form 1:1 monomeric adducts, (P(2,4,5)âCuX). The two compounds are isomorphous, crystallizing in the tetragonal space group P4â. For the chloride, a = 15.237 (4) â«, c = 12.373 (3) â«, Z

G. A. Bowmaker; J. D. Cotton; P. C. Healy; S. B. Silong; J. D. Kildea; B. W. Skelton; A. H. White

1989-01-01

293

Synthesis and properties of new tris(cyanoethyl)phosphine complexes of platinum (0,II), palladium (0,II), iridium (I) and rhodium (I)  

Microsoft Academic Search

The tris(cyanoethyl)phosphine (tcep) complexes trans-[PtCl2(tcep)2], cis-[PtMe2(tcep)2], and trans-[PtMeCl(tcep)2] are prepared by treatment of the corresponding [PtXY(cod)] (cod=1,5-cyclooctadiene) with tcep. Reduction of trans-[PtCl2(tcep)2] with NaBH4 gives trans-[PtHCl(tcep)2] which, in the presence of tcep and NEt3, gives the coordinatively unsaturated platinum(0) complex [Pt(tcep)3]. This coordinatively unsaturated species is also formed when [Pt(norbornene)3] reacts with tcep. [Pt(tcep)3] is very unreactive compared to its

A. Guy Orpen; Paul G. Pringle; Martin B. Smith; Kerry Worboys

1998-01-01

294

Reactions of elemental phosphorus and phosphine with electrophiles in superbasic systems: XVIII. Phosphorylation of 1-(chloromethyl)naphthalene with the elemental phosphorus  

Microsoft Academic Search

1-Chloromethylnaphthalene reacts with white and red phosphorus, and also with the “activated red phosphorus,” the complex\\u000a organophosphorus polymer of unknown structure obtained by irradiation of a solution of white phosphorus in benzene by the\\u000a 60Co source, in a system including KOH water solution, dioxane or benzene, and a phase transfer catalyst (22–98C, argon), to\\u000a form bis(1-naphthylmethyl)-and tris-(1-naphthylmethyl)phosphine oxides, and also

V. A. Kuimov; N. K. Gusarova; S. F. Malysheva; B. G. Sukhov; Yu. V. Smetannikov; N. P. Tarasova; A. V. Gusarov; B. A. Trofimov

2006-01-01

295

Tetrameric 1:1 and monomeric 1:3 complexes of silver(I) halides with tri( p-tolyl)-phosphine: A structural and biological study  

Microsoft Academic Search

Silver(I) halides react with tri(p-tolyl)phosphine (tptp, C21H21P) in MeOH\\/MeCN solutions in 1:1 or 1:3 molar ratios to give complexes of formulae {[AgCl(tptp)]4} (1) or [AgX(tptp)3] (X=Cl (2), Br (3), I (4)), respectively. The complexes were characterized by elemental analyses, and FT-IR far-IR, FT-Raman, TG and 1H, 13C, 31P NMR spectroscopic techniques. Crystal structures of complexes 2–4 were determined by X-ray

Sotiris Zartilas; Sotiris K. Hadjikakou; Nick Hadjiliadis; Nikolaos Kourkoumelis; Loukas Kyros; Maciej Kubicki; Martin Baril; Ian S. Butler; Spyros Karkabounas; Jan Balzarini

2009-01-01

296

Mechanistic studies on monodentate–ligand substitution of five-coordinate trigonal-bipyramidal platinum (II) complexes with tris[2-(diphenylphosphino)ethyl]phosphine  

Microsoft Academic Search

Reaction of the five-coordinate trigonal-bipyramidal platinum(II) complex, [Pt(pt)(pp3)](BF4) (pt=1-propanethiolate, pp3=tris[2-(diphenylphosphino)ethyl]phosphine), with I? in chloroform gave the five-coordinate square-pyramidal complex with a dissociated terminal phosphino group and an apically coordinated iodide ion in equilibrium. The thermodynamic parameters for the equilibrium between the trigonal-bipyramidal and square-pyramidal geometries, [Pt(pt)(pp3)]++I??[PtI(pt) (pp3)], and the kinetic parameters for the chemical exchange were obtained as follows: Kex298=7.5×10-1mol-1kg,

Sen-ichi Aizawa; Tadashi Kobayashi; Tatsuya Kawamoto

2005-01-01

297

Oligo-nuclear silver thiocyanate complexes with monodentate tertiary phosphine ligands, including novel 'cubane' and 'step' tetramer forms of AgSCN?:?PR3 (1:1)4.  

PubMed

Adducts of a number of tertiary pnicogen ligands ER(3) (triphenyl-phosphine and -arsine (PPh(3),AsPh(3)), diphenyl,2-pyridylphosphine (PPh(2)py), tris(4-fluorophenyl)phosphine (P(C(6)H(4)-4F)(3)), tris(2-tolyl)phosphine (P(o-tol)(3)), tris(cyclohexyl)phosphine (PCy(3))), with silver(I) thiocyanate, AgSCN are structurally and spectroscopically characterized. The 1:3 AgSCN?:?ER(3) complexes structurally defined (for PPh(3),AsPh(3) (diversely solvated)) take the form [(R(3)E)(3)AgX], the thiocyanate X = NCS being N-bound, thus [(Ph(3)E)Ag(NCS)]. A 1:2 complex with PPh(2)py, takes the binuclear form [(pyPh(2)P)(2)Ag()Ag(PPh(2)py)(2)] with an eight-membered cyclic core. 1:1 complexes are defined with PPh(2)py, P(o-tol)(3) and PCy(3); binuclear forms [(R(3)P)Ag()Ag(PR(3))] are obtained with P(o-tol)(3) (two polymorphs), while novel isomeric tetranuclear forms, which may be envisaged as dimers of dimers, are obtained with PPh(2)py, and, as further polymorphs, with PCy(3); these latter may be considered as extensions of the 'cubane' and 'step' forms previously described for [(R(3)E)AgX](4) (X = halide) complexes. Solvent-assisted mechanochemical or solvent-assisted solid-state synthesis methods were employed in some cases, where complexes could not be obtained by conventional solution methods, or where such methods yielded a mixture of polymorphs unsuitable for solid-state spectroscopy. The wavenumbers of the ?(CN) bands in the IR spectra are in broad agreement with the empirical rule that distinguishes bridging from terminal bonding, but exceptions occur for compounds that have a double SCN bridged dimeric structure, and replacement of PPh(3) with PPh(2)py apparently causes a significant decrease in ?(CN) to well below the range expected for bridging SCN in these structures. (31)P CP MAS NMR spectra yield additional parameters that allow a correlation between the structures and spectra. PMID:23114624

Bowmaker, Graham A; Di Nicola, Corrado; Effendy; Hanna, John V; Healy, Peter C; King, Scott P; Marchetti, Fabio; Pettinari, Claudio; Robinson, Ward T; Skelton, Brian W; Sobolev, Alexandre N; T?b?caru, Aurel; White, Allan H

2013-01-01

298

White electroluminescence from all-phosphorescent single polymers on a fluorinated poly(arylene ether phosphine oxide) backbone simultaneously grafted with blue and yellow phosphors.  

PubMed

On the basis of a fluorinated poly(arylene ether phosphine oxide) backbone with both high triplet energy and appropriate HOMO/LUMO levels, highly efficient all-phosphorescent single white-emitting polymers were designed and successfully synthesized via a "two-step addition" strategy. Simultaneous blue and yellow triplet emissions were achieved to generate white electroluminescence with a promising luminous efficiency as high as 18.4 cd/A (8.5 lm/W, 7.1%) and CIE coordinates of (0.31, 0.43). PMID:23215049

Shao, Shiyang; Ding, Junqiao; Wang, Lixiang; Jing, Xiabin; Wang, Fosong

2012-12-19

299

Synthesis of hybrid transition-metalloproteins via thiol-selective covalent anchoring of Rh-phosphine and Ru-phenanthroline complexes.  

PubMed

The preparation of hybrid transition metalloproteins by thiol-selective incorporation of organometallic rhodium- and ruthenium complexes is described. Phosphine ligands and two rhodium-diphosphine complexes bearing a carboxylic acid group were coupled to the cysteine of PYP R52G, yielding a metalloenzyme active in the rhodium catalyzed hydrogenation of dimethyl itaconate. The successful coupling was shown by (31)P NMR spectroscopy and ESI mass spectroscopy. In addition wild-type PYP (PYP WT), PYP R52G and ALBP were successfully modified with a (eta(6)-arene) ruthenium(II) phenanthroline complex via a maleimide linker. PMID:20603670

den Heeten, René; Muñoz, Bianca K; Popa, Gina; Laan, Wouter; Kamer, Paul C J

2010-09-28

300

Electron-withdrawing\\/donating effects of substituents on the preparation of phosphinated 4,4?-diaminodiphenylmethane for soluble, anti-oxidative, and high-Tg polyimides  

Microsoft Academic Search

In this work, we reveal a strategy to prepare a phosphinated 4,4?-diaminodiphenylmethane, 1,1-bis(4-aminophenyl)-1-(6-oxido-6H-dibenz oxaphosphorin-6-yl)methane (3). During the preparation, it was found that the effect of the electron withdrawing\\/donating characteristic of substituents is crucial to the synthesis. A reaction mechanism including nucleophilic addition, reduction, and electrophilic substitution is proposed. Based on diamine (3), a series of polyimides (4a–4d) were

Ching Hsuan Lin; Sheng Lung Chang; Yu Ting Fang; Ming Hsien Chou

2012-01-01

301

AZIDE-SPECIFIC LABELLING OF BIOMOLECULES BY STAUDINGER-BERTOZZI LIGATION: PHOSPHINE DERIVATIVES OF FLUORESCENT PROBES SUITABLE FOR SINGLE-MOLECULE FLUORESCENCE SPECTROSCOPY  

PubMed Central

We describe the synthesis of phosphine derivatives of three fluorescent probes that have brightness and photostability suitable for single-molecule fluorescence spectroscopy and microscopy: Alexa488, Cy3B, and Alexa647. In addition, we describe procedures for use of these reagents in azide-specific, bioorthogonal labelling through use of the Staudinger-Bertozzi ligation and procedures for quantitation of labelling specificity and labelling efficiency. The reagents and procedures of this report enable chemoselective, site-selective labelling of azide-containing biomolecules for single-molecule fluorescence spectroscopy and microscopy.

Chakraborty, Anirban; Wang, Dongye; Ebright, Yon W.; Ebright, Richard H.

2010-01-01

302

The origin of enantioselectivity in the L-threonine-derived phosphine-sulfonamide catalyzed aza-Morita-Baylis-Hillman reaction: effects of the intramolecular hydrogen bonding.  

PubMed

L-Threonine-derived phosphine-sulfonamide 4 was identified as the most efficient catalyst to promote enantioselective aza-Morita-Baylis-Hillman (MBH) reactions, affording the desired aza-MBH adducts with excellent enantioselectivities. Density functional theory (DFT) studies were carried out to elucidate the origin of the observed enantioselectivity. The importance of the intramolecular N-H···O hydrogen-bonding interaction between the sulfonamide and enolate groups was identified to be crucial in inducing a high degree of stereochemical control in both the enolate addition to imine and the subsequent proton transfer step, affording aza-MBH reactions with excellent enantioselectivity. PMID:23774825

Lee, Richmond; Zhong, Fangrui; Zheng, Bin; Meng, Yuezhong; Lu, Yixin; Huang, Kuo-Wei

2013-08-01

303

Selective extraction of U(VI) and some other metals from nitric acid media by poly-phosphine poly-oxides  

SciTech Connect

For the selective extraction of radionuclides from nitrate media, the extractabilities of organo-poly-phosphine poly-oxides were examined in the form of impregnated resins. It was found that the extractability of 1,1,3,5,5-pentaphenyl-1,3,5-tri-phospha-pentane trioxide (PPTPT) for U(VI) is quite unusual with very high values at both low and high concentrations of nitric acid, which is not observed for other types of extractants. Thus, this extractant might be promising for the selective extraction of U(VI) in very high concentrations of HNO{sub 3}. (authors)

Nogami, M.; Sugiyama, Y.; Ikeda, Y. [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, 2-12-1-N1-34 O-okayama, Meguro-ku, Tokyo 152-8550 (Japan); Maruyama, K. [Mitsubishi Chemical, Corp., 1000 Kamoshida-cho, Aoba-ku, Yokohama 227-8502 (Japan)

2008-07-01

304

Cluster chemistry on surfaces: Characterization and catalytic studies of phosphine-stabilized platinum-gold clusters on silica and alumina supports  

Microsoft Academic Search

Cationic, phosphine-ligated Pt-Au cluster compounds, [Pt(AuPPhâ)â](NOâ)â (1) and [(PPhâ)Pt(AuPPhâ)â](NOâ)â (2), have been immobilized on silica and alumina supports. Characterization of the supported clusters by ³¹P MAS NMR, IR, and UV-visible spectroscopy and study by chemisorption and temperature-programmed desorption of CO show that the clusters are immobilized intact without measurable fragmentation or irreversible transformation. This is confirmed by quantitative desorption of

Irina V. G. Graf; Jeffrey W. Bacon; Mark B. Consugar; Michael E. Curley; Larry N. Ito; Louis H. Pignolet

1996-01-01

305

High-efficiency turquoise-blue electrophosphorescence from a Pt(II)-pyridyltriazolate complex in phosphine oxide host  

SciTech Connect

We have demonstrated high-efficiency turquoise-blue electrophosphorescence from the complex Pt(ptp)2 = bis[3,5–bis(2–pyridyl)–1,2,4–triazolato]platinum(II) doped in the wide band-gap, ambipolar phosphine oxide host HM-A1 = 4-(diphenylphosphoryl)-N,N-diphenylaniline. For devices with 5% Pt(ptp)2 doping in HM-A1, we have achieved a peak external quantum efficiency and power efficiency of (11.8 ± 0.6) % and (61.2 ± 5.9) lm/W with high-pixel values of 13.1 % and 70.6 lm/W, respectively. These parameters maintained (10.6 ± 0.2) % and (40.3 ± 1.2) lm/W at a brightness of 1000 cd/m2 with high-pixel values of 10.8 % and 41.6 lm/W. Examination of several device structures suggests that the high performance is due to improved charge transport and exciton confinement in the emissive region. Devices with 1-10% doping concentration exhibit turquoise-blue emissions (?max ~ 480 nm) with a monotonic decrease in monomer/excimer intensity ratio upon increasing the doping concentration. Devices with 5% doping exhibit sufficient blue contribution to attain white light upon combination with highly-doped or neat emissive layers of the same phosphor; the work herein represents a significant backdrop toward optimizing such white OLEDs given the performance metrics above, which to our knowledge represent the highest performance for OLEDs that exhibit blue emission maxima.

Bhansali, Unnat S.; Polikarpov, Evgueni; Swensen, James S.; Chen, Wei; Jia, Huiping; Gaspar, Daniel J.; Gnade, Bruce E.; Padmaperuma, Asanga B.; Omary, Mohammad A.

2009-12-10

306

Mercury(II) halide complexes of tertiary phosphines. Part XVII. Complexes of the very basic and sterically demanding ligand, tris(2,4,6-trimethoxyphenyl)phosphine (TMPP) of stoichiometry (TMPP) x (HgX 2) y (X=Cl, Br, I; x=1, 2; y=1: x=2, y=3: X=I; x=1, y=2). Crystal structures of the monomeric 1:1 complexes (TMPP)HgX 2 (X=Br, I) and (TMPP) (HgI 2) 2  

Microsoft Academic Search

Reactions between the bulky ligand tris(2,4,6-trimethoxyphenyl)phosphine (TMPP) and HgX2 (X=Cl, Br, I) in ethanol have been described. Complexes of stoichiometry (P:Hg) 1:1, 2:1 and 2:3 have been isolated and their spectral features discussed. The structures of the 1:1 bromide and iodide show them to be discrete monomers unlike most other tertiary phosphine analogues. Additionally a complex of stoichiometry TMPP(HgI2)2 has

Norman A Bell; Simon J Coles; Christopher P Constable; Michael B Hursthouse; Mark E Light; Rafizah Mansor; Nicholas J Salvin

2002-01-01

307

Heck-type coupling vs. conjugate addition in phosphine-rhodium catalyzed reactions of aryl boronic acids with alpha,beta-unsaturated carbonyl compounds: a systematic investigation.  

PubMed

The competition between Heck-type coupling and conjugate addition in phosphine-rhodium catalyzed reactions of aryl boronic acids with alpha,beta-unsaturated carbonyls has been systematically investigated in a toluene-H(2)O biphasic system. Aside from the intrinsic nature of rhodium and the enolization of carbonyls, the phosphine supporting ligand on rhodium, the ratio of aryl boronic acid to alpha,beta-unsaturated carbonyl and the pH value of the aqueous phase were found to affect the competition significantly. Highly selective rhodium-based catalyst systems have therefore been developed for both Heck-type coupling and conjugate addition by synergistically tuning the supporting ligand, the boronic acid to olefin ratio and other reaction conditions. Conjugate addition with selectivity >99% and Heck-type coupling with selectivity of up to 100%, 98% and 84% for acrylates, acrylamides and methyl vinyl ketone, respectively, could be achieved in the rhodium-catalyzed reactions of aryl boronic acids with alpha,beta-unsaturated carbonyls using the corresponding optimized rhodium-based catalyst systems. PMID:17622423

Zou, Gang; Guo, Jianping; Wang, Zhiyong; Huang, Wen; Tang, Jie

2007-07-28

308

Synthesis and coordination chemistry of a novel bidentate phosphine: 6-(diphenylphosphino)-1,3,5-triaza-7-phosphaadamantane (PTA-PPh2).  

PubMed

The upper rim of 1,3,5-triaza-7-phosphaadamantane (PTA) has been modified for the first time. Lithiation of PTA, with n-butyllithium, resulted in deprotonation of an alpha-phosphorus methylene and the formation of 1,3,5-triaza-7-phosphaadamantane-6-yllithium (PTA-Li). The chiral chelating phosphine 6-(diphenylphosphino)-1,3,5-triaza-7-phosphaadamantane (PTA-PPh2) was synthesized, in racemic form, by the reaction of PTA-Li with ClPPh2. PTA-PPh2 has been fully characterized in solution by multinuclear NMR spectroscopy and mass spectrometry and in the solid state by X-ray crystallography. The 31P NMR spectrum contains a pair of doublets at -19.8 and -100.1 ppm (d, (2)J(PP) = 65 Hz). Unlike PTA, the new bidentate phosphine, PTA-PPh2, is insoluble in aqueous solutions. Two group 6 metal carbonyl complexes, [M(CO)4(PTA-PPh2)] (M = W and Mo), were synthesized by the addition of PTA-PPh2 to cis-[M(CO)4(pip)2] and characterized by NMR spectroscopy, IR spectroscopy, and X-ray crystallography. Also reported are the solid-state structures of cis-[W(CO)4PTA2], cis-[W(CO)4(PTA)(PPh3)], and [W(CO)4DPPM] (DPPM = diphenylphosphinomethane). PTA-PPh2 appears to be sterically similar to and slightly more electron-donating than DPPM. PMID:16903731

Wong, Gene W; Harkreader, Jennifer L; Mebi, Charles A; Frost, Brian J

2006-08-21

309

?(3)-Iodo-tri-?(3)-sulfido-sulfidotris[tris-(4-methoxy-phen-yl)phosphine-?P]tri-copper(I)tungsten(VI) N,N-dimethyl-formide solvate.  

PubMed

A new W/S/Cu cluster, [Cu(3)WIS(4)(C(21)H(21)O(3)P)(3)]·C(3)H(7)NO, was formed by the reaction of ammonium tetra-thio-tungstate(VI), cuprous iodide and tris-(4-methoxy-phen-yl)phosphine in N,N-dimethyl-formamide. The title compound exhibits a heavily distorted cubane-like skeleton in which the average Cu-I, Cu-S and W-?(3)-S distances are 2.934, 2.302 and 2.249?Å, respectively. The W atom exhibits tetrahedral geometry, formed by three ?(3)-S and one terminal S atom; the W-S(terminal) bond length is 2.1426?(13)?Å. Each Cu atom is coordinated by one P atom from a tris-(4-methoxy-phen-yl)phosphine (mop), two ?(3)-S and one ?(3)-I atom, forming a distorted tetra-hedral coordination geometry. Some of the mop ligand methyl groups have large librations. Together with the three neutral mop ligands, the title compound is neutral; this contrasts with the all-halogen-coordinated Mo/S/Ag clusters with the same structure, which carry negative charge. PMID:21200642

Tang, Guodong; Zhang, Jinfang; Zhang, Chi

2007-01-01

310

Inorganic heterocyclic bis(phosphines): syntheses and structures of a 1,2-bis(diazasilaphosphetidino)ethane and its nickel, molybdenum, and rhodium complexes.  

PubMed

Synthesis and characterization of a new, highly electron-rich, chelating bis(phosphine), based on the ethanediyl-linked inorganic heterocycle [Me(2)Si(mu-N(t)Bu)(2)P], are reported. Treatment of nickel chloride with this bis(phosphine) afforded square-planar cis-[[Me(2)Si(mu-N(t)Bu)(2)PCH(2)](2)NiCl(2)], which features isometric nickel-chloride (2.2220(8) A) and nickel-phosphorus (2.1572(8) A) bonds. The ligand reacted with cis-[(piperidine)(2)Mo(CO)(4)] to form colorless cis-[[Me(2)Si(mu-N(t)Bu)(2)PCH(2)](2)Mo(CO)(4)], which has distorted octahedral geometry and long Mo-P bonds (2.5461(18) A). Because of its potential applications in hydrogenation catalysis cis-[[Me(2)Si(mu-N(t)()Bu)(2)PCH(2)](2)Rh(COD)]BF(4) was synthesized. This square-planar, cationic rhodium(I) complex, having symmetrical Rh-P (2.250(2) A) and Rh-C (2.305(6) A) bonds, is structurally related to bis(phospholano)- and bis(phosphetano)rhodium species. PMID:12470091

Schranz, Ingo; Lief, Graham R; Midstokke, Steven J; Stahl, Lothar

2002-12-16

311

Metabolism of aspirin and procaine in mice pretreated with O-4-nitrophenyl methyl(phenyl)phosphinate or O-4-nitrophenyl diphenylphosphinate  

SciTech Connect

Concentrations of (carboxyl-/sup 14/C)procaine in blood of mice were increased threefold for 27 min by exposure to O-4-nitrophenyl diphenylphosphinate 2 hr prior to (carboxyl-/sup 14/C)procaine injection ip, while there was no effect of O-4-nitrophenyl methyl(phenyl)phosphinate pretreatment. There was no effect of either organophosphinate on the primary hydrolysis of (acetyl-l-/sup 14/C)aspirin when assessed by the expiration of (/sup 14/C)carbon dioxide; however, O-4-nitrophenyl diphenylphosphinate pretreatment produced transient increases in blood concentrations of both (carboxyl-/sup 14/C)aspirin and (carboxyl-/sup 14/C)salicylic acid following administration of (carboxyl-/sup 14/C)aspirin. Liver carboxylesterase activity in O-4-nitrophenyl diphenylphosphinate pretreated mice was 11% of control activity. These results indicate the potential for drug interaction with O-4-nitrophenyl diphenylphosphinate but not with O-4-nitrophenyl methyl(phenyl)phosphinate. It appears that liver carboxylesterase activity has a minor role in hydrolysis of aspirin in vivo, but may be more important in procaine metabolism.

Joly, J.M.; Brown, T.M.

1986-07-01

312

Air-stable gold nanoparticles ligated by secondary phosphine oxides for the chemoselective hydrogenation of aldehydes: crucial role of the ligand.  

PubMed

The synthesis of air-stable and homogeneous gold nanoparticles (AuNPs) employing tert-butyl(naphthalen-1-yl)phosphine oxide as supporting ligand is described via NaBH4 reduction of a Au(I) precursor, [(tert-butyl(naphthalen-1-yl)phosphine oxide)AuCl]2. This highly reproducible and simple procedure furnishes small (1.24 ± 0.16 nm), highly soluble nanoparticles that are found to be highly active catalysts for the hydrogenation of substituted aldehydes, giving high conversions and chemoselectivities for a wide variety of substrates. In addition to catalytic studies the role of the novel stabilizer in the remarkable activity and selectivity exhibited by this system was interrogated thoroughly using a wide range of techniques, including ATR FT-IR, HRMAS NMR, XPS, and EDX spectroscopy. In particular, isotopic labeling experiments enabled us to probe the coordination mode adopted by the SPO ligand bound to the nanoparticle surface by ATR FT-IR spectroscopy. In combination with a series of control experiments we speculate that the SPO ligand demonstrates ligand-metal cooperative effects and plays a seminal role in the heterolytic hydrogenation mechanism. PMID:24444462

Cano, Israel; Chapman, Andrew M; Urakawa, Atsushi; van Leeuwen, Piet W N M

2014-02-12

313

The synthesis, NMR and X-ray analysis of tris(1-ethyl-2-isopropylimidazol-5-yl)phosphine gold (I)-2,3,4,6-tetra-O-acetyl-1-thio-?-D-glucopyranoside, a bifunctional auranofin analogue  

Microsoft Academic Search

A derivative of auranofin, a drug used in the treatment of rheumatoid arthritis, was synthesised and examined by NMR spectroscopy and X-ray crystallography. The derivative, which contains a trisimidazole phosphine, was designed to complex hard metals in addition to binding to the gold(I) centre.

R. A. Bell; C. J. L. Lock; C. Scholten; J. F. Valliant

1998-01-01

314

Arene ruthenium(II) complexes coordinated by phosphino and two phenoxide groups in tris(2,6-dimethoxyphenyl)phosphine: crystal structure of ( ? 6-1,2,3,4Me 4C 6H 2)Ru[P[ lcub]2,6-(MeO) 2C 6H 3[ rcub] [ lcub]2-O-6MeOC 6H 3[ rcub;] 2  

Microsoft Academic Search

The title compound has been prepared from bis[dichloro(?6-arene)ruthenium] (?6-arene = 1,2,3,4-C6Me4H2 (1a), p-cymene (1b) and tris(2,6-dimethoxyphenyl)phosphine (TDMPP). The crystal structure features a type of ?3-phosphino-two phenoxides coordination. Reactions with its related phosphines, bis(2,6-dimethoxyphenyl)phenylphosphine (BDMPP) and (2,6-dimethoxyphenyl)diphenylphosphine (MDMPP) gave complexes with ?2-phosphino-phenoxide and ?1-phosphino coordinations, and trans-RuCl2(MDMPP)2, depending on phosphines and arene groups.

Yasuhiro Yamamoto; Ryoichi Sato; Mayumi Ohshima; Fumiko Matsuo; Chihiro Sudoh

1995-01-01

315

Structure, magnetism and colour in simple bis(phosphine)nickel(II) dihalide complexes: an experimental and theoretical investigation.  

PubMed

The complex [1,2-bis(di-tert-butylphosphanyl)ethane-?(2)P,P']diiodidonickel(II), [NiI2(C18H40P2] or (dtbpe-?(2)P)NiI2, [dtbpe is 1,2-bis(di-tert-butylphosphanyl)ethane], is bright blue-green in the solid state and in solution, but, contrary to the structure predicted for a blue or green nickel(II) bis(phosphine) complex, it is found to be close to square planar in the solid state. The solution structure is deduced to be similar, because the optical spectra measured in solution and in the solid state contain similar absorptions. In solution at room temperature, no (31)P{(1)H} NMR resonance is observed, but the very small solid-state magnetic moment at temperatures down to 4?K indicates that the weak paramagnetism of this nickel(II) complex can be ascribed to temperature independent paramagnetism, and that the complex has no unpaired electrons. The red [1,2-bis(di-tert-butylphosphanyl)ethane-?(2)P,P']dichloridonickel(II), [NiCl2(C18H40P2] or (dtbpe-?(2)P)NiCl2, is very close to square planar and very weakly paramagnetic in the solid state and in solution, while the maroon [1,2-bis(di-tert-butylphosphanyl)ethane-?(2)P,P']dibromidonickel(II), [NiBr2(C18H40P2] or (dtbpe-?(2)P)NiBr2, is isostructural with the diiodide in the solid state, and displays paramagnetism intermediate between that of the dichloride and the diiodide in the solid state and in solution. Density functional calculations demonstrate that distortion from an ideal square plane for these complexes occurs on a flat potential energy surface. The calculations reproduce the observed structures and colours, and explain the trends observed for these and similar complexes. Although theoretical investigation identified magnetic-dipole-allowed excitations that are characteristic for temperature-independent paramagnetism (TIP), theory predicts the molecules to be diamagnetic. PMID:24311488

Schultz, Madeleine; Plessow, Philipp-Nikolaus; Rominger, Frank; Weigel, Laura

2013-12-15

316

Iridium(III) Hydrido N-Heterocyclic Carbene-Phosphine Complexes as Catalysts in Magnetization Transfer Reactions  

PubMed Central

The hyperpolarization (HP) method signal amplification by reversible exchange (SABRE) uses para-hydrogen to sensitize substrate detection by NMR. The catalyst systems [Ir(H)2(IMes)(MeCN)2(R)]BF4 and [Ir(H)2(IMes)(py)2(R)]BF4 [py = pyridine; R = PCy3 or PPh3; IMes = 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene], which contain both an electron-donating N-heterocyclic carbene and a phosphine, are used here to catalyze SABRE. They react with acetonitrile and pyridine to produce [Ir(H)2(NCMe)(py)(IMes)(PPh3)]BF4 and [Ir(H)2(NCMe)(py)(IMes)(PCy3)]BF4, complexes that undergo ligand exchange on a time scale commensurate with observation of the SABRE effect, which is illustrated here by the observation of both pyridine and acetonitrile HP. In this study, the required symmetry breaking that underpins SABRE is provided for by the use of chemical inequivalence rather than the previously reported magnetic inequivalence. As a consequence, we show that the ligand sphere of the polarization transfer catalyst itself becomes hyperpolarized and hence that the high-sensitivity detection of a number of reaction intermediates is possible. These species include [Ir(H)2(NCMe)(py)(IMes)(PPh3)]BF4, [Ir(H)2(MeOH)(py)(IMes)(PPh3)]BF4, and [Ir(H)2(NCMe)(py)2(PPh3)]BF4. Studies are also described that employ the deuterium-labeled substrates CD3CN and C5D5N, and the labeled ligands P(C6D5)3 and IMes-d22, to demonstrate that dramatically improved levels of HP can be achieved as a consequence of reducing proton dilution and hence polarization wastage. By a combination of these studies with experiments in which the magnetic field experienced by the sample at the point of polarization transfer is varied, confirmation of the resonance assignments is achieved. Furthermore, when [Ir(H)2(pyridine-h5)(pyridine-d5)(IMes)(PPh3)]BF4 is examined, its hydride ligand signals are shown to become visible through para-hydrogen-induced polarization rather than SABRE.

2013-01-01

317

Molecular control of the nanoscale: effect of phosphine-chalcogenide reactivity on CdS-CdSe nanocrystal composition and morphology.  

PubMed

We demonstrate molecular control of nanoscale composition, alloying, and morphology (aspect ratio) in CdS-CdSe nanocrystal dots and rods by modulating the chemical reactivity of phosphine-chalcogenide precursors. Specific molecular precursors studied were sulfides and selenides of triphenylphosphite (TPP), diphenylpropylphosphine (DPP), tributylphosphine (TBP), trioctylphosphine (TOP), and hexaethylphosphorustriamide (HPT). Computational (DFT), NMR ((31)P and (77)Se), and high-temperature crossover studies unambiguously confirm a chemical bonding interaction between phosphorus and chalcogen atoms in all precursors. Phosphine?chalcogenide precursor reactivity increases in the order: HPTE < TOPE < TBPE < DPPE phosphine, the selenide is always more reactive than the sulfide. CdS(1-x)Se(x) quantum dots were synthesized via single injection of a R(3)PS-R(3)PSe mixture to cadmium oleate at 250 °C. X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV/Vis and PL optical spectroscopy reveal that relative R(3)PS and R(3)PSe reactivity dictates CdS(1-x)Se(x) dot chalcogen content and the extent of radial alloying (alloys vs core/shells). CdS, CdSe, and CdS(1-x)Se(x) quantum rods were synthesized by injection of a single R(3)PE (E = S or Se) precursor or a R(3)PS-R(3)PSe mixture to cadmium-phosphonate at 320 or 250 °C. XRD and TEM reveal that the length-to-diameter aspect ratio of CdS and CdSe nanorods is inversely proportional to R(3)PE precursor reactivity. Purposely matching or mismatching R(3)PS-R(3)PSe precursor reactivity leads to CdS(1-x)Se(x) nanorods without or with axial composition gradients, respectively. We expect these observations will lead to scalable and highly predictable "bottom-up" programmed syntheses of finely heterostructured nanomaterials with well-defined architectures and properties that are tailored for precise applications [corrected]. PMID:22519805

Ruberu, T Purnima A; Albright, Haley R; Callis, Brandon; Ward, Brittney; Cisneros, Joana; Fan, Hua-Jun; Vela, Javier

2012-06-26

318

Bio-catalysts and catalysts based on ruthenium(II) polypyridyl complexes imparting diphenyl-(2-pyridyl)-phosphine as a co-ligand  

Microsoft Academic Search

Reactions of the ruthenium complexes [Ru(?3-tpy)(PPh3)Cl2], [Ru(?3-tptz)(PPh3)Cl2] and [Ru(?3-tpy)Cl3] [tpy=2,2?:6?,2??-terpyridine; tptz=2,4,6-tris(2-pyridyl)-1,3,5-triazine] with diphenyl-(2-pyridyl)-phosphine (PPh2Py) have been investigated. The complexes [Ru(?3-tpy)(PPh3)Cl2] and [Ru(?3-tptz)(PPh3)Cl2] reacted with PPh2Py to afford [Ru(?3-tpy)(?1-P-PPh2Py)2Cl]+ (1) and [Ru(?3-tptz)(?1-P-PPh2Py)2Cl]+ (2), which were isolated as their tetrafluoroborate salts. Under analogous conditions, [Ru(?3-tpy)Cl3] gave a neutral complex [Ru(?3-tpy)(?1-PPh2Py)Cl2] (3). Upon treatment with an excess of NH4PF6 in methanol, 1 and

Prashant Kumar; Ashish Kumar Singh; Rampal Pandey; Daya Shankar Pandey

2011-01-01

319

Reaction of [Ru 3(CO) 12] with tri(2-furyl)phosphine: Di and tri-substituted triruthenium and phosphido-bridged diruthenium complexes  

Microsoft Academic Search

Reaction of [Ru3(CO)12] with tri(2-furyl)phosphine, P(C4H3O)3, at 40°C in the presence of a catalytic amount of Na[Ph2CO] furnishes two triruthenium complexes [Ru3(CO)10{P(C4H3O)3}2] (1) and [Ru3(CO)9{P(C4H3O)3}3] (2) with the ligand coordinated through the phosphorus atom. Treatment of 1 and 2 with Me3NO at 40°C affords the dinuclear phosphido-bridged complexes [Ru2(CO)6(?-?1,?2-C4H3O){?-P(C4H3O)2}] (3) and [Ru2(CO)5(?-?1,?2-C4H3O){?-P(C4H3O)2}{P(C4H3O)3}] (4), respectively, that are formed via phosphorus–carbon bond

Noorjahan Begum; Mohammad A. Rahman; Mohammad R. Hassan; Derek A. Tocher; Ebbe Nordlander; Graeme Hogarth; Shariff E. Kabir

2008-01-01

320

Tris{N-[bis-(dimethyl-amino)phosphino-yl]-2,2,2-trichloro-acetamido}(triphenyl-phosphine oxide)holmium(III)  

PubMed Central

In the title compound, [Ho(C6H12Cl3N3O2P)3(C18H15OP)], the HoIII ion is surrounded by six O atoms from the three bidentate N-[bis­(dimethyl­amino)phosphino­yl]-2,2,2-trichloro­acetamido ligands (L ?) and by one O atom from the triphenyl­phosphine oxide ligand, with the formation of a distorted monocapped octa­hedron. In one ligand L ?, the trichloro­methyl group is rotationally disordered between two orientations in a 1:1 ratio, while two dimethyl­amino groups in another ligand L ? are disordered between two conformations, each with the same 1:1 ratio.

Amirkhanov, Oleksiy V.; Marchenko, Ivan O.; Moroz, Olesia V.; Sliva, Tetyana Yu.; Fritsky, Igor O.

2010-01-01

321

Thermal and MS studies of silver(I) 2,2-dimethylbutyrate complexes with tertiary phosphines and their application for CVD of silver films  

Microsoft Academic Search

[Ag2(CH3CH2C(CH3)2COO)2] (1), [Ag2(CH3CH2C(CH3)2COO)2(PMe3)2] (2) and [Ag2(CH3CH2C(CH3)2COO)2(PEt3)2] (3) were prepared and characterized by MS-EI; 1H, 13C, 31P NMR, variable temperature IR (VT-IR) spectroscopy and thermal analysis. MS and VT-IR data analysis suggests bidentate bridging carboxylates and monodentately bonded phosphines in the solid phase. The same methods used for gas phase analysis of 1–2 proved [(CH3CH2C(CH3)2COO)Ag2]+ as the main ion, which could

I. Szyma?ska; P. Piszczek; R. Szcz?sny; E. Sz?yk

2007-01-01

322

Band gap engineering of quaternary-alloyed ZnCdSSe quantum dots via a facile phosphine-free colloidal method.  

PubMed

We demonstrate the synthesis of quaternary-alloyed Zn(x)Cd(1-x)S(y)Se(1-y) quantum dots (ZnCdSSe QQDs) across the entire composition range (x, y) = 0 to 1 with a size tunable from 4.0 to 10.0 nm by a facile, "green", phosphine-free, low-cost colloidal method. The ZnCdSSe QQDs have both composition- and size-dependent band gaps, which can be hybrid-engineered to span the entire visible spectrum. The new ZnCdSSe QQDs are easy to synthesize and have high quantum yields (up to 65%) without the necessity of overcoating a shell. These new quantum dots may find broad uses in biolabeling, biosensing, light-emitting diodes, and other nanodevice applications. PMID:19928806

Deng, Zhengtao; Yan, Hao; Liu, Yan

2009-12-16

323

E-type delayed fluorescence of a phosphine-supported Cu2(mu-NAr2)2 diamond core: harvesting singlet and triplet excitons in OLEDs.  

PubMed

A highly emissive bis(phosphine)diarylamido dinuclear copper(I) complex (quantum yield = 57%) was shown to exhibit E-type delayed fluorescence by variable temperature emission spectroscopy and photoluminescence decay measurement of doped vapor-deposited films. The lowest energy singlet and triplet excited states were assigned as charge transfer states on the basis of theoretical calculations and the small observed S(1)-T(1) energy gap. Vapor-deposited OLEDs doped with the complex in the emissive layer gave a maximum external quantum efficiency of 16.1%, demonstrating that triplet excitons can be harvested very efficiently through the delayed fluorescence channel. The function of the emissive dopant in OLEDs was further probed by several physical methods, including electrically detected EPR, cyclic voltammetry, and photoluminescence in the presence of applied current. PMID:20557045

Deaton, Joseph C; Switalski, Steven C; Kondakov, Denis Y; Young, Ralph H; Pawlik, Thomas D; Giesen, David J; Harkins, Seth B; Miller, Alex J M; Mickenberg, Seth F; Peters, Jonas C

2010-07-14

324

Phenylcarbazole and phosphine oxide/sulfide hybrids as host materials for blue phosphors: effectively tuning the charge injection property without influencing the triplet energy.  

PubMed

Compared with red and green phosphorescent organic light-emitting diodes (PHOLEDs), efficient blue PHOLEDs are still scarce, because it is difficult for the host materials for blue phosphors to achieve a trade-off between a wide triplet energy and good charge injection properties. We theoretically studied a series of hybrid phosphine oxide/sulfide-phenylcarbazole host molecules (PO(S)PhCBZs) for blue phosphors through different linkage modes between phenylcarbazole (PhCBZ) and phosphine oxide/sulfide (PO/PS) moieties. The results indicate that the singlet excitons of all PO(S)-PhCBZs are delocalized over the entire molecule with intramolecular charge transfer (ICT) character and different linkage modes cause various degrees of ICT, which determines the injection abilities of carriers from neighboring layers following the order: PO-Phs (PO linked to the phenyl of PhCBZ) > para-POs (PO linked to the para-positions of PhCBZ) > meta-POs (PO linked to the meta-positions of PhCBZ). By contrast, the triplet excitons are confined to the carbazole unit for all PO(S)-PhCBZs. High triplet energies (E(T)) are therefore kept up for all systems, except for para-POs showing a slight drop in E(T) due to the delocalization of their triplet excitons to the phenyl moiety of PhCBZ. All hybrid PO(S)-PhCBZs, especially PO(s)-Phs, exhibit an enhancement in electron injection and triplet energy compared with the most widely used host material (N,N-dicarbazolyl-3,5-benzene) for blue PHOLEDs, and thereby have great potential for application in highly efficient light emitting diodes. PMID:22193557

Wu, Jie; Liao, Yi; Wu, Shui-Xing; Li, Hai-Bin; Su, Zhong-Min

2012-02-01

325

Syntheses and characterization of trigonal-bipyramidal rhodium(I) complexes of tris(2-(diphenylphosphino)ethyl) phosphine and determination of a spectroscopic trans-influence series by sup 31 P ( sup 1 H) NMR spectroscopy  

Microsoft Academic Search

A series of low-spin, five-coordinate rhodium(I) complexes of the tripod ligand tris(2-(diphenylphosphino)ethyl) phosphine, PPâ, were synthesized and characterized by elemental analyses, infrared spectra, and ³¹P(¹H) NMR spectra. The complexes have trigonal-bipyramidal geometries in which the PPâ ligand occupies four of the five sites of C{sub 3ν} symmetry and the variable fifth ligand is monodentate. The ³¹P NMR spectral patterns are

J. J. Gambaro; W. H. Hohman; D. W. Meek

1989-01-01

326

Phosphoryl group as a strong ?-donor anionic phosphine-type ligand: a combined experimental and theoretical study on long-lived room temperature luminescence of the [Ru(tpy)(bpy)(Ph2PO)]+ complex.  

PubMed

A phosphoryl Ru(II) polypyridyl complex was prepared in a one-pot process. Theoretical analysis suggests that the phosphoryl ligand may be viewed as a strong ?-donor anionic phosphine L-type ligand. State-of-the-art free-energy profile calculations on the excited states demonstrate that both favorable thermodynamic and kinetic factors are responsible for the remarkable room temperature luminescence properties of the phosphoryl complex. PMID:24471922

Lebon, Emilie; Sylvain, Rémy; Piau, Rémi E; Lanthony, Cloé; Pilmé, Julien; Sutra, Pierre; Boggio-Pasqua, Martial; Heully, Jean-Louis; Alary, Fabienne; Juris, Alberto; Igau, Alain

2014-02-17

327

Determination of total tiopronin in human plasma by LC–ESI–MS using tris (2-carboxy-ethyl) phosphine as reducing reagent and methyl acrylate as derivatization reagent for the thiol group  

Microsoft Academic Search

A quantitative method for the determination of total tiopronin (TP) in human plasma was developed by liquid chromatography with electrospray ionisation (ESI) mass spectrometric detection. After reduction with tris (2-carboxy-ethyl) phosphine (TCEP) and derivatization with methyl acrylate (MA) for the thiol group of TP, plasma samples were processed successively by deproteinization and solid phase extraction. N-acetyl-l-cysteine (NAC) was selected as

Jianfang Liu; Honghai Wu; Yanning Hou

2006-01-01

328

Comparison of the electrochemical and luminescence properties of two carbazole-based phosphine oxide Eu(III) complexes: effect of different bipolar ligand structures.  

PubMed

The photoluminescence (PL), electrochemical, and electroluminescence (EL) properties of Eu(III) complexes, [Eu(cppo)(2)(tta)(3)] (1) and [Eu(cpo)(2)(tta)(3)] (2; TTA = 2-thenoyltrifluoroacetonate) with two carbazole-based phosphine oxide ligands, 9-[4-(diphenylphosphinoyl)phenyl]-9H-carbazole (CPPO) and 9-(diphenylphosphoryl)-9H-carbazole (CPO), which have different bipolar structures, donor-pi-spacer-acceptor (D-pi-A) or donor-acceptor (D-A) systems respectively, are investigated. The CPPO with D-pi-A architecture has improved PL properties, such as higher PL efficiency and more efficient intramolecular energy transfer, than CPO with the D-A architecture. Gaussian simulation proved the bipolar structures and the double-carrier injection ability of the ligands. The carrier injection abilities of triphenylphosphine oxide, CPO, and CPPO are gradually improved. Notably, the Gaussian and electrochemical investigations indicate that before and after coordination, the carrier injection ability of the ligands show remarkable changes because of the particularity of the D-pi-A and D-A systems. The electrochemical studies demonstrate that coordination induces the electron cloud to migrate from electron-rich carbazole to electron-poor diphenylphosphine oxide, and consequently increases the electron-cloud density on diphenylphosphine oxide, which weakens its ability for electron affinity and induces the elevation of LUMO energy levels of the complexes. Significantly, the pi-spacer in the D-pi-A system exhibits a distinct buffer effect on the variation of the electron-cloud density distribution of the ligand, which is absent in the D-A system. It is demonstrated that the adaptability of the D-pi-A systems, especially for coordination, is stronger than that of D-A systems, which facilitates the modification of the complexes by designing multifunctional ligands purposefully. 1 seems favorable as the most efficient electroluminescent Eu(III) complex with greater brightness, higher efficiencies, and more stable EL spectra than 2. These investigations demonstrate that the phosphine oxide ligands with D-pi-A architecture are more appropriate than those with D-A architecture to achieve multifunctional electroluminescent Eu(III) complexes. PMID:18563765

Xu, Hui; Yin, Kun; Huang, Wei

2008-08-25

329

Rhodium(I) and iridium(I) complexes containing bidentate phosphine-imidazolyl donor ligands as catalysts for the hydroamination and hydrothiolation of alkynes.  

PubMed

A series of novel cationic and neutral rhodium and iridium complexes containing bidentate phosphine-imidazolyl donor ligands of the general formulae [M(ImP)(COD)]BPh(4) (M = Rh, ImP = ImP2, 3; ImP1a, 4a; ImP1b, 4b and M = Ir, ImP = ImP2, 5; ImP1a, 6a and ImP1b, 6b), [Ir(ImP)(CO)(2)]BPh(4) (ImP = ImP2, 7; ImP1a, 8a and ImP1b, 8b), [Rh(ImP1b)(CO)(2)]BPh(4) (10b) and [M(ImP)(CO)Cl] (M = Rh, ImP = ImP2, 11; ImP1b,12 and M = Ir, ImP = ImP2, 13; ImP1b, 14 ) where COD = 1,5-cyclooctadiene, ImP2 = 1-methyl-2-[(2-(diphenylphosphino)ethyl]imidazole, 1; ImP1a = 1-methyl-2-[(diphenylphosphino)methyl]imidazole, 2a and ImP1b = 2-[(diisopropylphosphino)methyl]-1-methylimidazole, 2b were successfully synthesised. The solid state structures of 3, 6a, 11 and 12 were determined by single crystal X-ray diffraction analysis. A number of these complexes are effective as catalysts for the intramolecular hydroamination of 4-pentyn-1-amine to 2-methyl-1-pyrroline. The cationic complexes are significantly more effective than analogous neutral complexes. The cationic iridium complex 8b , containing the phosphine-imidazolyl ligand with the bulky isopropyl groups on the phosphorus donor, is more efficient than analogous complexes with the phenyl substituents on the phosphorus donor atom, 7 and 8a. The complexes 7-8b are also moderately effective in catalysing the addition of thiophenol to a range of terminal alkynes. In contrast to the hydroamination reaction, placement of the isopropyl group on the phosphorus donor leads to a decrease in the reactivity of the resulting metal complexes as catalysts for the hydrothiolation reaction. PMID:19381423

Field, Leslie D; Messerle, Barbara A; Vuong, Khuong Q; Turner, Peter

2009-05-14

330

Exponential Sum Absorption Coefficients of Phosphine from 2750 to 3550/cm for Application to Radiative Transfer Analyses on Jupiter and Saturn  

NASA Technical Reports Server (NTRS)

PH3 exponential sum k coefficients were computed between 2750 and 3550/cm (2.82-3.64 (microns), in view of future application to radiative transfer analyses of Jupiter and Saturn in a phosphine absorption band near 3 microns. The temperature and pressure of this data set cover the ranges from 80 to 350 K and from 10 (exp -3)to 10(exp 1) bars, respectively. Transmission uncertainty incurred by the use of the k coefficients is smaller than a few percent as long as the radiation is confined above an altitude of a few bars in the giant planets. In spectral regions of weak absorption at high pressures close to 10 bars, contributions from far wings of strong absorption lines must be carefully taken into account. Our data set helps map the three-dimensional distribution of PH3 on the giant planets, revealing their global atmospheric dynamics extending down to the deep interior. The complete k coefficient data set of this work is available at the Web site of the NASA Planetary Data System Atmospheres Node.

Temma, T.; Baines, K. H.; Butler, R. A. H.; Brown, L. R.; Sagui, L.; Kleiner, I.

2006-01-01

331

Direct measurement of active thiol metabolite levels of clopidogrel in human plasma using tris(2-carboxyethyl)phosphine as a reducing agent by LC-MS/MS.  

PubMed

A simple, robust, and rapid LC-MS/MS method has been developed and validated for the simultaneous quantitation of clopidogrel and its active metabolite (AM) in human plasma. Tris(2-carboxyethyl)phosphine (TCEP) was used as a reducing agent to detect the AM as a disulfide-bonded complex with plasma proteins. Mixtures of TCEP and human plasma were deproteinized with acetonitrile containing 10 ng/mL of clopidogrel-d4 as an internal standard (IS). The mixtures were separated on a C18 RP column with an isocratic mobile phase consisting of 0.1% formic acid in acetonitrile and water (90:10, v/v) at a flow rate of 0.3 mL/min. Detection and quantification were performed using ESI-MS. The detector was operated in selected reaction-monitoring mode at m/z 322.0?211.9 for clopidogrel, m/z 356.1?155.2 for the AM, and m/z 326.0?216.0 for the IS. The linear dynamic range for clopidogrel and its AM were 0.05-20 and 0.5-200 ng/mL, respectively, with correlation coefficients (r) greater than 0.9976. Precision, both intra- and interday, was less than 8.26% with an accuracy of 87.6-106%. The validated method was successfully applied to simultaneously analyze clinical samples for clopidogrel and its AM. PMID:23686964

Park, Jung Bae; Bae, Soo Hyeon; Jang, Su-Min; Noh, Won Jun; Hong, Jang-Hee; Yoon, Kee Dong; Kang, Han Chang; Bae, Soo Kyung

2013-07-01

332

Blue to true-blue phosphorescent Ir(III) complexes bearing a nonconjugated ancillary phosphine chelate: strategic synthesis, photophysics, and device integration.  

PubMed

We report the design and synthesis of Ir(III) complexes functionalized with substituted pyridyl cyclometalate or azolate chromophores, plus one newly designed nonconjugated phosphine chelate, which not only greatly restricts its participation in the lowest-lying electronic transition but also enhances the coordination strength. These two key factors lead to fine-tuning of the phosphorescence chromaticity toward authentic blue and simultaneously suppress, in part, the nonradiative deactivation. This conceptual design presents a novel strategy in achieving heretofore uncommon, high-efficiency blue and true-blue phosphorescence. The fabrication of the organic light-emitting devices (OLEDs) employing phosphorescent dopants [Ir(dfpbpy)(2)(P(wedge)N)] (1b) and [Ir(fppz)(2)(P(wedge)N)] (3) was successfully made, for which the abbreviations (dfpbpy)H, (fppz)H, and (P(wedge)N)H represent 2-(4,6-difluorophenyl)-4-tert-butylpyridine, 3-(trifluoromethyl)-5-(2-pyridyl)pyrazole, and 5-(diphenylphosphinomethyl)-3-(trifluoromethyl)pyrazole, respectively. Of particular interest is the 3-doped OLEDs, which exhibit remarkable maximum efficiencies of 6.9%, 8.1 cd A(-1), and 4.9 lm W(-1), together with a true-blue chromaticity CIE(x,y) = 0.163, with 0.145 recorded at 100 cd m(-2). PMID:20353234

Chiu, Yuan-Chieh; Chi, Yun; Hung, Jui-Yi; Cheng, Yi-Ming; Yu, Ya-Chien; Chung, Ming-Wen; Lee, Gene-Hsiang; Chou, Pi-Tai; Chen, Chung-Chia; Wu, Chung-Chih; Hsieh, Hsi-Ying

2009-02-01

333

Determination of ascorbic acid and dehydroascorbic acid in biological samples by high-performance liquid chromatography using subtraction methods: reliable reduction with tris[2-carboxyethyl]phosphine hydrochloride.  

PubMed

Determination of dehydroascorbic acid in biological samples most commonly involves indirect measurement. The concentration is calculated by subtraction of the measured ascorbic acid concentration from that of total ascorbic acid analyzed after reduction of the dehydroascorbic acid present; a methodology also referred to as subtraction methods. Consequently, successful determination of dehydroascorbic acid is dependent on proper sample handling, quantitative reduction of the compound, and accurate quantification of both ascorbic acid and total ascorbic acid. In this paper, the recently introduced reductant tris[2-carboxyethyl]phosphine (TCEP) is evaluated as a reliable alternative to the commonly used reducing agent dithiothreitol (DTT). The results show that TCEP offers a more efficient reduction of dehydroascorbic acid at low pH compared to that of DTT. Moreover, while DTT maintains a reducing sample environment for less than 24 h, TCEP show complete protection from oxidation of ascorbic acid for at least 96 h following sample preparation. Removal of TCEP prior to analysis is unnecessary. A revised HPLC-EC method incorporating TCEP as reductant as well as the coanalysis of isoascorbic acid and uric acid is presented. The within- and between-day coefficients of variation for the complete assay are less than 1.5 and 3.5% for all analytes. As a whole, the method presented here is simpler and more reliable than existing methods. PMID:10860503

Lykkesfeldt, J

2000-06-15

334

In vitro and in vivo anticancer activity of copper(I) complexes with homoscorpionate tridentate tris(pyrazolyl)borate and auxiliary monodentate phosphine ligands.  

PubMed

Tetrahedral copper(I) TpCuP complexes 1-15, where Tp is a N,N,N-tris(azolyl)borate and P is a tertiary phosphine, have been synthesized and characterized by means of NMR, ESI-MS, and XAS-EXAFS, and X-ray diffraction analyses on the representative complexes 1 and 10, respectively. All copper(I) complexes were evaluated for their antiproliferative activity against a panel of human cancer cell lines (including cisplatin and multidrug-resistant sublines). The two most effective complexes [HB(pz)3]Cu(PCN), 1, and [HB(pz)3]Cu(PTA), 2, showed selectivity toward tumor vs normal cells, inhibition of 26S proteasome activity associated with endoplasmic reticulum (ER) stress, and unfolded protein response (UPR) activation. No biochemical hallmarks of apoptosis were detected, and morphology studies revealed an extensive cytoplasmic vacuolization coherently with a paraptosis-like cell death mechanism. Finally, the antitumor efficacy of complex 1 was validated in the murine Lewis Lung Carcinoma (LLC) model. PMID:24793739

Gandin, Valentina; Tisato, Francesco; Dolmella, Alessandro; Pellei, Maura; Santini, Carlo; Giorgetti, Marco; Marzano, Cristina; Porchia, Marina

2014-06-12

335

Synthesis and spectroscopic studies of silver and rhodium mono- and polynuclear complexes with multidentate phosphines (Ph2P)2CHR (R = H, Me, PPh2)  

Microsoft Academic Search

Trinuclear [{(Ph{2}P){3}CH}Ag{3}(O{2}CR'){3}], dinuclear [{(Ph{2}P){2}CHR}Ag{2}(O{2}CR'){2}], [{(Ph{2}P){2}CHR}{2}Ag{2}](BF{4}){2} and (Rh{2}(Cl)(CO){2}{(Ph{2}P){2}CHMe}{2}][RhCl{2}(CO){2}], and mononuclear (Rh{(Ph{2}P){2}CHR}{2}](BF{4}), (Rh{(Ph{2}P){2}CHR}{2}HCl](BF{4}), d [Rh{(Ph{2}P){2}CHR}{2}Cl(HgCl)](BF{4}) and (Rh{(Ph{2}P){2}CHR}{2}O{2}](BF{4}) (R = H,Me) were synthesized from the phosphines tris(diphenylphosphino)methane ((Ph{2}P){3}CH), bis(diphenylphosphino)methane ((Ph{2}P){2}CH{2}) and 1,1-bis(diphenylphosphino)ethane ((Ph{2}P){2}CHMe). The }1{H, }1{}3{C and }3{}1{P NMR spectra were investigated and for the mononuclear rhodium compounds compared with their 1,2-bis(diphenylphosphino)ethane and 1,3-bis(diphenylphosphino)propane analogues. The }3{}1{P NMR spectra of the silver complexes

G. van Koten; A. F. M. J. van der Ploeg

1981-01-01

336

Broad HOMO-LUMO gap tuning through the coordination of a single phosphine, aminophosphine or phosphite onto a Ru(tpy)(bpy)2+ core.  

PubMed

The synthesis of new ruthenium(II) terpyridine bipyridine complexes bearing a phosphorus(III) ligand is presented. The steric and electronic properties of the phosphorus ligand were varied using aminophosphines, alkyl and aryl phosphites and the bulky tri(isopropyl)phosphine. All complexes were characterized by multi-nuclear NMR spectroscopy, mass spectrometry and X-ray diffraction analysis. The electronic properties of the complexes were probed by cyclic voltammetry, absorption and luminescence spectroscopy. The complexes do not show luminescence at room temperature, whereas at 77 K in an alcoholic matrix, emission is observed in the range 600-650 nm with lifetimes of 3.5-5.5 micros, originating from 3MLCT states. The MLCT transition spans over 65 nm, which corresponds to a variation of 0.4 eV in the HOMO-LUMO gap. The oxidation potential of the ruthenium varies over a broad range of 290 mV, from +1.32 V vs. SCE with L = PiPr3 to +1.61 V vs. SCE with L = P(OPh)3. This range is unprecedented upon the variation of a single monodentate ligand coordinated by the same heteroatom in the same oxidation and charge states. This work underlines the specific capacity of phosphorus in bringing up a large variety of electronic properties by changing its substituents. PMID:18854901

Dixon, Isabelle M; Lebon, Emilie; Loustau, Gilles; Sutra, Pierre; Vendier, Laure; Igau, Alain; Juris, Alberto

2008-11-01

337

Extraction of phenol from aqueous solutions by means of supported liquid membrane (MLS) containing tri-n-octyl phosphine oxide (TOPO).  

PubMed

This paper deals with the liquid-liquid extraction and the facilitated transport through a supported liquid membrane (SLM) system of aqueous phenol using tri-n-octyl phosphine oxide (TOPO) dissolved in an appropriate organic solvent. Phenol has been quantitatively extracted from aqueous acidic solutions using TOPO dissolved in kerosene as organic phase. The effect of TOPO concentration dissolved in kerosene on the extraction efficiency reveals that TOPO combined with phenol in the ratio of 1:1. Using a flat-sheet SLM (FSSLM) system, more than 65% of the initial phenol content in the feed phase was extracted and stripped in a NaOH aqueous receiving phase. The important operational variables affecting the facilitated transport of phenol through the FSSLM system studied are concentration of TOPO, membrane viscosity, feed phase pH, initial phenol concentration, polymeric support type and membrane stability. Regardless of its comparatively low extraction efficiency of phenol, the SLM based on TOPO exhibits higher long-term stability as compared to tributyl phosphate (TBP). Elaborated SLM system retained its stability and initial performance during the 5 days long experiment contrary to the TBP-SLM system where a time dependent negative tendency (transport efficiency decline) was observed. PMID:21871728

Zidi, Chiraz; Tayeb, Rafik; Dhahbi, Mahmoud

2011-10-30

338

Degradation, cleanup, and reusability of octylphenyl-N,N{prime}-diisobutylcarbamoylmethyl phosphine oxide (CMPO) during partitioning of minor actinides from high level waste (HLW) solutions  

SciTech Connect

The radiolytic degradation of the extractant mixture 0.2 M octylphenyl-N,N{prime}-diisobutylcarbamoylmethyl phosphine oxide (CMPO) + 1.2 M tributyl phosphate in n-dodecane [to be utilized for the partitioning of minor actinides from high level waste (HLW) solutions of PUREX origin] has been investigated in contact with 3 M HNO{sub 3} or synthetic pressurized heavy water reactors (PHWR)-HLW solution under dynamic conditions. The distribution ratios of Am, Zr, Fe and Ru with the irradiated extractant mixture at varying doses have been determined under various aqueous phase conditions and correlated with the formation of degradation products. Various cycles of loading the extractant mixture with Am from PHWR-HLW, irradiating at a fixed gamma dose, and then primary and secondary clean-up of the solvent has been carried out to illustrate its reusability during partitioning of minor actinides from actual HLW solutions. The degradation products of CMPO have been identified by employing GC and GC-MS techniques.

Mathur, J.N.; Murali, M.S.; Ruikar, P.B.; Nagar, M.S.; Sipahimalani, A.T.; Bauri, A.K.; Banerji, A. [Bhabha Atomic Research Centre, Bombay (India)

1998-10-01

339

Water-soluble ruthenium complexes containing tris( m-sulfonatophenyl) phosphine (TPPTS). Preparation of a series of [Ru(H)( ? 6-arene)(TPPTS) 2]Cl complexes, [Ru(H) 2(CO)(TPPTS) 3] and revisited procedures for previously described ruthenium-TPPTS compounds  

Microsoft Academic Search

The TPPTS ligand is the trihydrated form of the sodium salt of tris(m-sulfonatophenyl)phosphine. Complexes [Ru(Cl)(?-Cl)(TPPTS)2]21 and [Ru(H)(X)(TPPTS)3], where X = Cl 2, OAc 3, have been prepared by a phosphine exchange from [Ru(Cl)2(PPh3)3] and [Ru(H)(X)(PPh3)3] as previously described by Basset. Complex 1 presents in solution a solvolysis phenomenon which has been studied by 31P NMR. Complex 1 is a useful

Marc Hernandez; Philippe Kalck

1997-01-01

340

Pd(OAc)2/DABCO as an efficient and phosphine-free catalytic system for the synthesis of single and double Weinreb amides by the aminocarbonylation of aryl iodides.  

PubMed

This work reports a mild, stable and efficient Pd(OAc)2/DABCO catalysed protocol for the synthesis of single and double Weinreb amides. Double Weinreb amides, having 1,4-phenylene- and biphenylene-linkers - important backbones for the synthesis of biologically active symmetrical resorcylate oligomer units - were synthesized by the double carbonylation of aryl diiodides. Notably, the reaction does not require any expensive or air/moisture sensitive phosphine ligands. DABCO was found to be an inexpensive and stable ligand for the Pd(OAc)2 catalysed carbonylation of aryl iodides under an atmospheric pressure of carbon monoxide, and offered excellent yields of the single and double Weinreb amides. PMID:24967832

Gadge, Sandip T; Bhanage, Bhalchandra M

2014-08-14

341

Synthesis, structure, and fluxional behavior of octahedral ruthenium(II) complexes with mixed oxygen-phosphine ligands. [sup 31]P DNMR spectroscopic studies, line shape analysis, and determination of rearrangement barriers  

Microsoft Academic Search

The synthesis and spectroscopic properties of ether-phosphine ruthenium(II) complexes of the type Cl[sub 2]Ru([cflx P O])[sub 2] (5a, 7a-10a) and trans-Cl[sub 2]Ru(CO)(P[approximately]O)([cflx P O]) (5b, 7b-10b) are reported. Temperature-dependent [sup 31]P NMR spectra of the fluxional complexes 1b-11b and cis-Cl[sub 2]Ru(CO)(P[approximately]O)([cflx P O]) (1c-3c) were measured and by using a modified version of DNMR5, computer-generated spectra were obtained and fitted

Ekkehard Lindner; Andrea Moeckel; Hermann August Mayer; Hartwig Kuehbauch; Riad Fawzi; Manfred Steimann

1993-01-01

342

Synthesis, characterization, in vitro cytotoxicity and anti-inflammatory activity of palladium(II) complexes with tertiary phosphines and heterocyclic thiolates: Crystal structure of [PdC 28H 19N 8PS 2  

Microsoft Academic Search

The new four-coordinated mononuclear palladium(II) complexes 1–9 with chelating heterocyclic thiolates and tertiary phosphines with general formula [Pd(L)nCl(R?R2P)] (L=Pym2SH (pyrimidine-2-thiolate), Pur6SH (purine-6-thiolate), Py2SH (pyridine-2-thiolate), R3P=PPh3, P(o-tolyl)3, PPh2Cl), n=1, 2) have been synthesized by the direct reaction of [PdCl2(R?R2P)2] with polyfunctional heterocyclic thiolates which display a wide variety of coordinations. These compounds were characterized by elemental analysis, FT-IR and multinuclear (1H,

Farkhanda Shaheen; Amin Badshah; Marcel Gielen; Christine Gieck; Mariyam Jamil; Dick de Vos

2008-01-01

343

A photochemical study of the kinetics of the reactions of NH2 with phosphine, ethylene, and acetylene using flash photolysis-laser induced fluorescence. Ph.D. Thesis Catholic Univ. of America; [ammonia in the atmosphere of Jupiter  

NASA Technical Reports Server (NTRS)

The photochemistry of the reactions of NH2 was investigated in an attempt to explain the existence of an abundance of ammonia in the Jovian atmosphere. The production of ammonia reservoirs from the coupling of ammonia with other atmospheric constituents was considered. The rate constants for the reactions of NH2 radicals with phosphine, acetylene, and ethylene were measured. Flash photolysis was used for the production of NH2 radicals and laser induced fluorescence was employed for radical detection. It was determined that the rates of the reactions were too slow to be significant as a source of ammonia reservoirs in the Jovian atmosphere.

Bosco, S. R.

1982-01-01

344

Computational study of the reaction of C6F6 with [IrMe(PEt3)3]: identification of a phosphine-assisted C-F activation pathway via a metallophosphorane intermediate.  

PubMed

Density functional theory calculations have been used to model the reaction of C6F6 with [IrMe(PEt3)3], which proceeds with both C-F and P-C bond activation to yield trans-[Ir(C6F5)(PEt3)2(PEt2F)], C2H4, and CH4 (Blum, O.; Frolow, F.; Milstein, D. J. Chem. Soc., Chem. Commun. 1991, 258). Using a model species, trans-[IrMe(PH3)2(PH2Et)], a low-energy mechanism involving nucleophilic attack of the electron-rich Ir metal center at C6F6 with displacement of fluoride has been identified. A novel feature of this process is the capture of fluoride by a phosphine ligand to generate a metallophosphorane intermediate [Ir(C6F5)(Me)(PH3)2(PH2EtF)]. These events occur in a single step via a 4-centered transition state, in a process that we have termed "phosphine-assisted C-F activation". Alternative mechanisms based on C-F activation via concerted oxidative addition or electron-transfer processes proved less favorable. From the metallophosphorane intermediate the formation of the final products can be accounted for by facile ethyl group transfer from phosphorus to iridium followed by beta-H elimination of ethene and reductive elimination of methane. The interpretation of phosphine-assisted C-F activation in terms of nucleophilic attack is supported by the reduced activation barriers computed with the more electron-rich model reactant trans-[IrMe(PMe3)2(PMe2Et)] and the higher barriers found with lesser fluorinated arenes. Reactivity patterns for a range of fluoroarenes indicate the dominance of the presence of ortho-F substituents in promoting phosphine-assisted C-F activation, and an analysis of the charge distribution and transition state geometries indicates that this process is controlled by the strength of the Ir-aryl bond that is being formed. PMID:18950169

Erhardt, Stefan; Macgregor, Stuart A

2008-11-19

345

Phosphine-free synthesis from 1D Pb(OH)Cl nanowires to 0D and 1D PbSe nanocrystals.  

PubMed

In this paper, we report a new phosphine-free, low-cost, low-temperature colloidal method of controlled synthesis of PbSe nanocrystals in both zero-dimension (0D) and one-dimension (1D). Different from the widely used "hot injection" method and "nonprecursor injection" method, the novelty of this new method is that it does not require a nucleation process. Instead, high-quality presynthesized 1D Pb(OH)Cl nanowires (?80 to ?160 nm in diameter) can be directly used as a Pb precursor and reacted with a Se precursor to form monodisperse dot-shaped 0D cubic PbSe and 1D orthorhombic PbSe nanowires. 0D cubic PbSe nanocrystals begin to form at elevated temperatures after the Se precursor is added to react with Pb(OH)Cl nanowires. By prolonging the reaction time for 3 h, good self-assembled 0D cubic PbSe nanocrystals can be synthesized with an average diameter of about 15 nm. Furthermore, such method has been demonstrated to synthsize high-quality 1D PbSe nanowires successfully with temperature as low as 110 °C. 1D PbSe nanowires possess a mean diameter of 15-24 nm with the shortest and longest length from 600 nm to 5 ?m. The only sharp and strong peak, which is consistent with characteristic peaks of orthorhombic PbSe, indicates that the nanowires' elongation axis is in the [111] direction, and 0D cubic PbSe nanocrystals change to 1D orthorhombic PbSe nanowires completely. PMID:24066872

Shen, Huaibin; Li, Jinjie; Shang, Hangying; Niu, Jinzhong; Xu, Weiwei; Wang, Hongzhe; Guo, Fang; Li, Lin Song

2013-10-23

346

Potent Suppression of Kv1.3 Potassium Channel and IL-2 Secretion by Diphenyl Phosphine Oxide-1 in Human T Cells  

PubMed Central

Diphenyl phosphine oxide-1 (DPO-1) is a potent Kv1.5 channel inhibitor that has therapeutic potential for the treatment of atrial fibrillation. Many other Kv1.5 channel blockers also potently inhibit the Kv1.3 channel, but whether DPO-1 blocks Kv1.3 channels has not been investigated. The Kv1.3 channel is highly expressed in activated T cells, which is considered a favorable target for immunomodulation. Accordingly, we hypothesized that DPO-1 may exert immunosuppressive and anti-inflammatory effects by inhibiting Kv1.3 channel activity. In this study, DPO-1 blocked Kv1.3 current in a voltage-dependent and concentration-dependent manner, with IC50 values of 2.58 µM in Jurkat cells and 3.11 µM in human peripheral blood T cells. DPO-1 also accelerated the inactivation rate and negatively shifted steady-state inactivation. Moreover, DPO-1 at 3 µM had no apparent effect on the Ca2+ activated potassium channel (KCa) current in both Jurkat cells and human peripheral blood T cells. In Jurkat cells, pre-treatment with DPO-1 for 24 h decreased Kv1.3 current density, and protein expression by 48±6% and 60±9%, at 3 and 10 µM, respectively (both p<0.05). In addition, Ca2+ influx to Ca2+-depleted cells was blunted and IL-2 production was also reduced in activated Jurkat cells. IL-2 secretion was also inhibited by the Kv1.3 inhibitors margatoxin and charybdotoxin. Our results demonstrate for the first time that that DPO-1, at clinically relevant concentrations, blocks Kv1.3 channels, decreases Kv1.3 channel expression and suppresses IL-2 secretion. Therefore, DPO-1 may be a useful treatment strategy for immunologic disorders.

Zhao, Ning; Dong, Qian; Du, Li-Li; Fu, Xiao-Xing; Du, Yi-Mei; Liao, Yu-Hua

2013-01-01

347

Modulating the optoelectronic properties of large, conjugated, high-energy gap, quaternary phosphine oxide hosts: impact of the triplet-excited-state location.  

PubMed

The purposeful modulation of the optoelectronic properties was realised on the basis of a series of the large, conjugated, phosphine oxide hosts 9,9-bis-{4'-[2-(diphenylphosphinoyl)phenoxy]biphenyl-4-yl}-9H-fluorene (DDPESPOF), 9,9-bis-{3'-(diphenylphosphinoyl)-4'-[2-(diphenylphosphinoyl)phenoxy]biphenyl-4-yl}-9H-fluorene (DDPEPOF), 9-[4'-(9-{4'-[2-(diphenylphosphoryl)phenoxy]biphenyl-4-yl}-9H-fluoren-9-yl)biphenyl-4-yl]-9H-carbazole (DPESPOFPhCz) and 9-[4'-(9-{3'-(diphenylphosphoryl)-4'-[2-(diphenylphosphoryl)phenoxy]biphenyl-4-yl}-9H-fluoren-9-yl)biphenyl-4-yl]-9H-carbazole (DPEPOFPhCz). The last two are quaternary with fluorenyls as linking bridges, diphenylphosphine oxide (DPPO) moieties as electron acceptors and diphenylethers and carbazolyls as two different kinds of electron donors. Owing to the fine-organised molecular structures and the mixed indirect and multi-insulating linkages, all of these hosts achieve the same first triplet energy levels (T1) of 2.86 eV for exothermic energy transfer to phosphorescent dopants. The first singlet energy levels (S1) and the carrier injection/transportation ability of the hosts were accurately modulated, so that DPESPOFPhCz and DPEPOFPhCz revealed extremely similar optoelectronic properties. However, the T1 state of the former is localised on fluorenyl, whereas the carbazolyl mainly contributes to the T1 state of the latter. A lower driving voltages and much higher efficiencies of the devices based on DPESPOFPhCz indicated that the chromophore-localised T1 state can suppress the quenching effects through realising independent contributions from the different functional groups to the optoelectronic properties and the embedding and protecting effect on the T1 states by peripheral carrier transporting groups. PMID:23766090

Zhang, Zhen; Zhang, Zhensong; Chen, Runfeng; Jia, Jilin; Han, Chunmiao; Zheng, Chao; Xu, Hui; Yu, Donghui; Zhao, Yi; Yan, Pengfei; Liu, Shiyong; Huang, Wei

2013-07-15

348

Identification and Characterization of Mechanism of Action of P61-E7, a Novel Phosphine Catalysis-Based Inhibitor of Geranylgeranyltransferase-I  

PubMed Central

Small molecule inhibitors of protein geranylgeranyltransferase-I (GGTase-I) provide a promising type of anticancer drugs. Here, we first report the identification of a novel tetrahydropyridine scaffold compound, P61-E7, and define effects of this compound on pancreatic cancer cells. P61-E7 was identified from a library of allenoate-derived compounds made through phosphine-catalyzed annulation reactions. P61-E7 inhibits protein geranylgeranylation and blocks membrane association of geranylgeranylated proteins. P61-E7 is effective at inhibiting both cell proliferation and cell cycle progression, and it induces high p21CIP1/WAF1 level in human cancer cells. P61-E7 also increases p27Kip1 protein level and inhibits phosphorylation of p27Kip1 on Thr187. We also report that P61-E7 treatment of Panc-1 cells causes cell rounding, disrupts actin cytoskeleton organization, abolishes focal adhesion assembly and inhibits anchorage independent growth. Because the cellular effects observed pointed to the involvement of RhoA, a geranylgeranylated small GTPase protein shown to influence a number of cellular processes including actin stress fiber organization, cell adhesion and cell proliferation, we have evaluated the significance of the inhibition of RhoA geranylgeranylation on the cellular effects of inhibitors of GGTase-I (GGTIs). Stable expression of farnesylated RhoA mutant (RhoA-F) results in partial resistance to the anti-proliferative effect of P61-E7 and prevents induction of p21CIP1/WAF1 and p27Kip1 by P61-E7 in Panc-1 cells. Moreover, stable expression of RhoA-F rescues Panc-1 cells from cell rounding and inhibition of focal adhesion formation caused by P61-E7. Taken together, these findings suggest that P61-E7 is a promising GGTI compound and that RhoA is an important target of P61-E7 in Panc-1 pancreatic cancer cells.

Chan, Lai N.; Fiji, Hannah D. G.; Watanabe, Masaru; Kwon, Ohyun; Tamanoi, Fuyuhiko

2011-01-01

349

Single-Crystal (31)P NMR and X-ray Diffraction Study of a Molybdenum Phosphine Complex: (5-Methyldibenzophosphole)pentacarbonylmolybdenum(0).  

PubMed

The molecular structure of (5-methyldibenzophosphole)pentacarbonylmolybdenum(0), 1, has been determined by X-ray crystallography. The crystal is monoclinic C2/c, Z = 8, with unit cell dimensions of: a = 31.113(2) Å, b =7.7917(5) Å, c = 17.9522(12) Å, and beta = 122.135(4) degrees. Least-squares refinement converged to R(F) = 0.0245 for 2407 independent reflections. The molecular structure is typical of phosphine-substituted metal carbonyls. It contains an approximate mirror plane which bisects the dibenzophosphole framework. Phosphorus-31 NMR spectra of powder and single-crystal samples of 1 have been obtained with cross-polarization and (1)H high-power decoupling. The (31)P CP/MAS NMR spectra exhibit exceptionally well-resolved satellites due to spin-spin coupling interactions with (95,97)Mo (I = (5)/(2)). Using first-order perturbation theory, the multiplets have been analyzed to yield (1)J((95,97)Mo,(31)P) = 123(2) Hz and estimates of the molybdenum nuclear quadrupolar coupling constants, chi((95)Mo) = -0.87 MHz and chi((97)Mo) = 10.1 MHz. Phosphorus-31 NMR spectra of a large single crystal of 1 have been investigated as a function of orientation about three orthogonal axes in the applied magnetic field. Analysis of the data yields the three principal components of the phosphorus chemical shift tensor, delta(11) = 112 ppm, delta(22) = -23 ppm, and delta(33) = -40 ppm; delta(22) lies close to the Mo-P bond (8 degrees ), while delta(11) lies in the approximate mirror plane. The phosphorus chemical shift tensor determined for 1 is compared with the limited anisotropic phosphorus shift data available in the literature. PMID:11670035

Eichele, Klaus; Wasylishen, Roderick E.; Maitra, Kalyani; Nelson, John H.; Britten, James F.

1997-07-30

350

Mitochondria are primary targets in apoptosis induced by the mixed phosphine gold species chlorotriphenylphosphine-1,3-bis(diphenylphosphino)propanegold(I) in melanoma cell lines.  

PubMed

Based on previous evidence indicating a selective cytotoxic activity of the mixed phosphine gold complex chlorotriphenylphosphine-1,3-bis(diphenylphosphino)propanegold(I) for melanoma cells, we investigated the cellular bases of its antiproliferative effect in a panel of human melanoma cell lines (JR8, SK-Mel-5, Mel-501, 2/60, 2/21 and GRIG). The drug consistently induced a dose-dependent inhibition of cell growth, with IC50 values ranging from 0.8 to 2.3 microM and, when tested under the same experimental conditions, its cytotoxic activity was higher than (from 2- to 5-fold) or comparable to that of cisplatin as a function of cell lines. The ability of the gold complex to activate programmed cell death was assessed in JR8 and 2/60 cells, and a dose-dependent increase in cells with an apoptotic nuclear morphology was observed in both cell lines (up to 40 and 66% of the overall cell population, for JR8 and 2/60 cell lines, respectively). Such an apoptotic response was mediated by a dose-dependent loss of mitochondrial membrane potential, cytochrome c and Smac/DIABLO release from mitochondria into cytosol and enhanced caspase-9 and caspase-3 catalytic activity. A reduced or completely abrogated expression of the anti-apoptotic proteins c-IAP1, XIAP and survivin in drug-treated cells was also observed. Overall, results from the study indicate that chlorotriphenylphosphine-1,3-bis(diphenylphosphino)propanegold(I) markedly inhibits melanoma cell growth by inducing mitochondria-mediated apoptosis and suggest it as a good candidate for additional evaluation as an anticancer agent against melanoma. PMID:17188248

Caruso, Francesco; Villa, Raffaella; Rossi, Miriam; Pettinari, Claudio; Paduano, Francesco; Pennati, Marzia; Daidone, Maria Grazia; Zaffaroni, Nadia

2007-03-15

351

Synthesis, structure, and fluxional behavior of octahedral ruthenium(II) complexes with mixed oxygen-phosphine ligands. [sup 31]P DNMR spectroscopic studies, line shape analysis, and determination of rearrangement barriers  

SciTech Connect

The synthesis and spectroscopic properties of ether-phosphine ruthenium(II) complexes of the type Cl[sub 2]Ru([cflx P O])[sub 2] (5a, 7a-10a) and trans-Cl[sub 2]Ru(CO)(P[approximately]O)([cflx P O]) (5b, 7b-10b) are reported. Temperature-dependent [sup 31]P NMR spectra of the fluxional complexes 1b-11b and cis-Cl[sub 2]Ru(CO)(P[approximately]O)([cflx P O]) (1c-3c) were measured and by using a modified version of DNMR5, computer-generated spectra were obtained and fitted to the experimental spectra. Graphic application of the Eyring equation to the kinetic data afforded the thermodynamic parameters [Delta]H[double dagger], [Delta]S[double dagger], and [Delta]G[double dagger]. Complex 11b with the strong basic four-membered ether-phosphine 11 crystallizes in the monoclinic space group P2[sub 1]/n, with a = 11.974(2) [Angstrom], b = 10.877(2) [Angstrom], c = 29.567(6) [Angstrom], [beta] = 96.34(3)[degrees], Z = 4, and V = 3827.2(12) [Angstrom][sup 3] (R = 0.075 and R[sub w] = 0.076). 33 refs., 4 figs., 4 tabs.

Lindner, E.; Moeckel, A.; Mayer, H.A.; Kuehbauch, H.; Fawzi, R.; Steimann, M. (Inst. fuer Anorganische Chemie der Universitaet, Tuebingen (Germany))

1993-03-31

352

Determination des parametres optimaux intervenant dans la mise au point d'une nouvelle methode de purification de l'oxide de tri-n-octyl phosphine (TOPO). (Study of some physical parameters for a novel TOPO purification tec hnic using zinc).  

National Technical Information Service (NTIS)

The present work deals with the optimization study of certain parameters necessary to the development of a novel method of purification which can be applied for tri-n-octyl phosphine oxyde in synthetic mixtures. The procedure is based on the study of proc...

A. Hamidi M. Achache L. Meddour B. Zaoui

1995-01-01

353

Structural Properties, Cytotoxicity, and Anti-Inflammatory Activity of Silver(I) Complexes with tris(p-tolyl)Phosphine and 5-Chloro-2-Mercaptobenzothiazole  

PubMed Central

The synthesis and characterization of the silver(I) chloride complex of formula {[AgCI(CMBZT)(TPTP)2] · (MeOH)} (1) (CMBZT = 5-chloro-2-mercaptobenzothiazole, TPTP = tris(p-tolyl)phosphine) is described. Also the structure of the hydrate derivative {[AgCI(TPTP)3] · (0.5 · H2O)} (2) of the corresponding known anhydrous silver complex (Zartilas et al., 2009), and the polymorph 3 of the known [AgI(TPTP)3] complex (Zartilas et al., 2009) were determined and compared with the known ones. In addition, the structure of the known one silver(I) cluster {[AgI(TPTP)]4} (4) (Meijboom et al., 2009) was re-determined at 120(2) K and possible Ag-Ag interactions were analyzed. The compounds 1–4 were characterized by X-ray crystallography at r.t (1) and 120 K (2–4). All these complexes and {[(Et3NH)+]2 · [Ag6(?3-Hmna)4(?3-mna)2]2? · (DMSO)2 · (H2O)} (5) (Hmna = 2-mercaptonicotinic acid) were evaluated for cytotoxic and anti-inflammatory activity. The in vitro testing of cytotoxic activity of 1–5 against leiomyosarcoma cancer cells (LMS), were evaluated with Trypan Blue and Thiazolyl Blue Tetrazolium Bromide or 3-(4.5-dimethylthiazol-2-yl)-2.5-diphenyltetrazolium bromide (MTT) assays. The flow cytometry assay for complex 1 and showed that at 15??M of 1, 62.38% of LMS cells undergo apoptosis, while 7% of LMS cells undergo cell necrosis. The antitumor activity of 3 is comparable with that of its reported polymorph (Zartilas et al., 2009). The anti-inflammatory, activity of complexes 1–3 and 5 was also studied. The activity towards cell viability was 2 > 3 > 5 > 1 > 4, while the order of the inhibitory activity in cell growth proliferation follows the order, 2 > 3 > 1 > 4 > 5. The anti-inflammatory activity on the other hand is 1 > 2 > 5 > ? >3.

Kyros, L.; Kourkoumelis, N.; Kubicki, M.; Male, L.; Hursthouse, M. B.; Verginadis, I. I.; Gouma, E.; Karkabounas, S.; Charalabopoulos, K.; Hadjikakou, S. K.

2010-01-01

354

Comparative study of phosphine and N-heterocyclic carbene stabilized Group?13 adducts [L(EH3)] and [L2(E2H(n))].  

PubMed

Quantum chemical calculations using density functional theory at the BP86/TZ2P level have been carried out to determine the geometries and stabilities of Group?13 adducts [(PMe3)(EH3)] and [(PMe3)2(E2H(n))] (E = B-In; n = 4, 2, 0). The optimized geometries exhibit, in most cases, similar features to those of related adducts [(NHC(Me))(EH3)] and [(NHC(Me))2(E2H(n))] with a few exceptions that can be explained by the different donor strengths of the ligands. The calculations show that the carbene ligand L = NHC(Me) (:C(NMeCH)2) is a significantly stronger donor than L = PMe3. The equilibrium geometries of [L(EH3)] possess, in all cases, a pyramidal structure, whereas the complexes [L2(E2H4)] always have an antiperiplanar arrangement of the ligands L. The phosphine ligands in [(PMe3)2(B2H2)], which has Cs symmetry, are in the same plane as the B2H2 moiety, whereas the heavier homologues [(PMe3)2(E2H2)] (E = Al, Ga, In) have Ci symmetry in which the ligands bind side-on to the E2H2 acceptor. This is in contrast to the [(NHC(Me))2(E2H2)] adducts for which the NHC(Me) donor always binds in the same plane as E2H2 except for the indium complex [(NHC(Me))2(In2H2)], which exhibits side-on bonding. The boron complexes [L2(B2)] (L = PMe3 and NHC(Me)) possess a linear arrangement of the LBBL moiety, which has a B?B triple bond. The heavier homologues [L2(E2)] have antiperiplanar arrangements of the LEEL moieties, except for [(PMe3)2(In2)], which has a twisted structure in which the PInInP torsion angle is 123.0°. The structural features of the complexes [L(EH3)] and [L2(E2H(n))] can be explained in terms of donor-acceptor interactions between the donors L and the acceptors EH3 and E2H(n), which have been analyzed quantitatively by using the energy decomposition analysis (EDA) method. The calculations predict that the hydrogenation reaction of the dimeric magnesium(I) compound L'MgMgL' with the complexes [L(EH3)] is energetically more favorable for L = PMe3 than for NHC(Me). PMID:23512819

Holzmann, Nicole; Stasch, Andreas; Jones, Cameron; Frenking, Gernot

2013-05-10

355

Extending the coordination capabilities of tertiary phosphines and arsines: preparation, molecular structure, and reactivity of dinuclear rhodium complexes with PR3 and AsR3 in a doubly bridging coordination mode.  

PubMed

The reactions of [Rh2(kappa2-acac)2(mu-CPh2)2(mu-PR3)] (PR3= PMe34, PMe2Ph 7, PEt38) with an equimolar amount of Me3SiX (X = Cl, Br, I) afforded the unsymmetrical complexes [Rh2X(kappa2-acac)(mu-CPh2)2(mu-PR3)]5, 9-12, which contain the phosphine in a semi-bridging coordination mode. From 4 and excess Me3SiCl, the tetranuclear complex [[Rh2Cl(mu-Cl)(mu-CPh2)2(mu-PMe3)]2]6 was obtained. In contrast, the reaction of 4 with an excess of Me3SiX (X = Br, I) yielded the dinuclear complexes [Rh2X2(mu-CPh2)2(mu-PMe3)]13, 14 in which, as shown by the X-ray crystal structure analysis of 14, the bridging phosphine is coordinated in a truly symmetrical bonding mode. While related compounds with PEt3 and PMe2Ph as bridging ligands were prepared on a similar route, the complex [Rh2Cl2(mu-CPh2)2(mu-PiPr3)]19 was obtained from the mixed-valence species [(PiPr3)Rh(mu-CPh2)2Rh(kappa2-acac)2]17 and HCl. The reaction of [Rh2(kappa2-acac)2(mu-CPh2)2(mu-SbiPr3)]3 with AsMe3 gave the related Rh(mu-AsMe3)Rh compound 21. With Me3SiCl, the acac ligands of 21 can be replaced stepwise by chloride to give [Rh2Cl(kappa2-acac)(mu-CPh2)2(mu-AsMe3)]23 and [[Rh2Cl(mu-Cl)(mu-CPh2)2(mu-AsMe3)]2]24, the latter being isomorphous to the phosphine-bridged dimer 6. PMID:15252485

Pechmann, Thomas; Brandt, Carsten D; Werner, Helmut

2004-03-21

356

Determination of total tiopronin in human plasma by LC-ESI-MS using tris (2-carboxy-ethyl) phosphine as reducing reagent and methyl acrylate as derivatization reagent for the thiol group.  

PubMed

A quantitative method for the determination of total tiopronin (TP) in human plasma was developed by liquid chromatography with electrospray ionisation (ESI) mass spectrometric detection. After reduction with tris (2-carboxy-ethyl) phosphine (TCEP) and derivatization with methyl acrylate (MA) for the thiol group of TP, plasma samples were processed successively by deproteinization and solid phase extraction. N-acetyl-l-cysteine (NAC) was selected as internal standard undergoing the same treatment as TP. The method was validated that it could meet the need of biological analysis. The lower limit of quantitation (LLOQ) of TP in plasma was 0.02microg/mL. Finally, the method was successfully applied to a pharmacokinetic study in 20 healthy Chinese male volunteers after an oral dose of 200mg TP tablets. PMID:16904957

Liu, Jianfang; Wu, Honghai; Hou, Yanning

2006-11-21

357

Reactivity of {(Ph 3P)Pt[?-? 2-H?SiH(Ar)]} 2 (Ar=2-isopropyl-6-methylphenyl) with phosphines. X-ray crystal structure of trans-{(dppe)Pt[?-SiH(Ar)]} 2  

Microsoft Academic Search

The dinuclear Pt?Si complex {(Ph3P)Pt{?-?2-H?SiH(IMP)]}2 (trans-1a–cis-1b=3:1; IMP=2-isopropyl-6-methylphenyl) reacted with basic phosphines such as 1,2-bis(diphenylphosphino)ethane (dppe) and dimethylphenylphosphine (PMe2Ph) to afford different dinuclear Pt?Si complexes with loss of H2, {(P)2Pt[?-SiH(IMP)]}2 [P=dppe, trans-2a (major), cis-2b (trace); PMe2Ph, 3 (trans only)]. Complexes 2 and 3 were characterized by multinuclear NMR spectroscopy and X-ray crystallography (2a). In contrast, the reaction of 1a,b with the

Janet Braddock-Wilking; Yanina Levchinsky; Nigam P. Rath

2002-01-01

358

Behavioral effects of gamma-hydroxybutyrate, its precursor gamma-butyrolactone, and GABA(B) receptor agonists: time course and differential antagonism by the GABA(B) receptor antagonist 3-aminopropyl(diethoxymethyl)phosphinic acid (CGP35348).  

PubMed

Gamma-hydroxybutyrate (GHB) is used therapeutically and recreationally. The mechanism by which GHB produces its therapeutic and recreational effects is not entirely clear, although GABA(B) receptors seem to play an important role. This role could be complex, because there are indications that different GABA(B) receptor mechanisms mediate the effects of GHB and the prototypical GABA(B) receptor agonist baclofen. To further explore possible differences in underlying GABA(B) receptor mechanisms, the present study examined the effects of GHB and baclofen on operant responding and their antagonism by the GABA(B) receptor antagonist 3-aminopropyl(diethoxymethyl)phosphinic acid (CGP35348). Pigeons were trained to peck a key for access to food during response periods that started at different times after the beginning of the session. In these pigeons, GHB, its precursor gamma-butyrolactone (GBL), and the GABA(B) receptor agonists baclofen and 3-aminopropyl(methyl)phosphinic acid hydrochloride (SKF97541) decreased the rate of responding in a dose- and time-dependent manner. CGP35348 shifted the dose-response curve of each agonist to the right, but the magnitude of the shift differed among the agonists. Schild analysis yielded a pA(2) value of CGP35348 to antagonize GHB and GBL [i.e., 3.9 (3.7-4.2)] that was different (P = 0.0011) from the pA(2) value to antagonize baclofen and SKF97541 [i.e., 4.5 (4.4-4.7)]. This finding is further evidence that the GABA(B) receptor mechanisms mediating the effects of GHB and prototypical GABA(B) receptor agonists are not identical. A better understanding of the similarities and differences between these mechanisms, and their involvement in the therapeutic effects of GHB and baclofen, could lead to more effective medications with fewer adverse effects. PMID:19564487

Koek, Wouter; Mercer, Susan L; Coop, Andrew; France, Charles P

2009-09-01

359

Behavioral Effects of ?-Hydroxybutyrate, Its Precursor ?-Butyrolactone, and GABAB Receptor Agonists: Time Course and Differential Antagonism by the GABAB Receptor Antagonist 3-Aminopropyl(diethoxymethyl)phosphinic Acid (CGP35348)  

PubMed Central

?-Hydroxybutyrate (GHB) is used therapeutically and recreationally. The mechanism by which GHB produces its therapeutic and recreational effects is not entirely clear, although GABAB receptors seem to play an important role. This role could be complex, because there are indications that different GABAB receptor mechanisms mediate the effects of GHB and the prototypical GABAB receptor agonist baclofen. To further explore possible differences in underlying GABAB receptor mechanisms, the present study examined the effects of GHB and baclofen on operant responding and their antagonism by the GABAB receptor antagonist 3-aminopropyl(diethoxymethyl)phosphinic acid (CGP35348). Pigeons were trained to peck a key for access to food during response periods that started at different times after the beginning of the session. In these pigeons, GHB, its precursor ?-butyrolactone (GBL), and the GABAB receptor agonists baclofen and 3-aminopropyl(methyl)phosphinic acid hydrochloride (SKF97541) decreased the rate of responding in a dose- and time-dependent manner. CGP35348 shifted the dose-response curve of each agonist to the right, but the magnitude of the shift differed among the agonists. Schild analysis yielded a pA2 value of CGP35348 to antagonize GHB and GBL [i.e., 3.9 (3.7–4.2)] that was different (P = 0.0011) from the pA2 value to antagonize baclofen and SKF97541 [i.e., 4.5 (4.4–4.7)]. This finding is further evidence that the GABAB receptor mechanisms mediating the effects of GHB and prototypical GABAB receptor agonists are not identical. A better understanding of the similarities and differences between these mechanisms, and their involvement in the therapeutic effects of GHB and baclofen, could lead to more effective medications with fewer adverse effects.

Koek, Wouter; Mercer, Susan L.; Coop, Andrew; France, Charles P.

2009-01-01

360

Cationic rhodium mono-phosphine fragments partnered with carborane monoanions [closo-CB11H6X6]- (X = H, Br). Synthesis, structures and reactivity with alkenes.  

PubMed

Addition of the new phosphonium carborane salts [HPR(3)][closo-CB(11)H(6)X(6)] (R = (i)Pr, Cy, Cyp; X = H 1a-c, X = Br 2a-c; Cy = C(6)H(11), Cyp = C(5)H(9)) to [Rh(nbd)(mu-OMe)](2) under a H(2) atmosphere gives the complexes Rh(PR(3))H(2)(closo-CB(11)H(12)) 3 (R = (i)Pr 3a, Cy 3b, Cyp 3c) and Rh(PR(3))H(2)(closo-CB(11)H(6)Br(6)) 4 (R = (i)Pr 4a, Cy 4b, Cyp 4c). These complexes have been characterised spectroscopically, and for 4b by single crystal X-ray crystallography. These data show that the {Rh(PR(3))H(2)}(+) fragment is interacting with the lower hemisphere of the [closo-CB(11)H(6)X(6)](-) anion on the NMR timescale, through three Rh-H-B or Rh-Br interactions for complexes 3 and 4 respectively. The metal fragment is fluxional over the lower surface of the cage anion, and mechanisms for this process are discussed. Complexes 3a-c are only stable under an atmosphere of H(2). Removing this, or placing under a vacuum, results in H(2) loss and the formation of the dimer species Rh(2)(PR(3))(2)(closo-CB(11)H(12))(2) 5a (R = (i)Pr), 5b (R = Cy), 5c (R = Cyp). These dimers have been characterised spectroscopically and for 5b by X-ray diffraction. The solid state structure shows a dimer with two closely associated carborane monoanions surrounding a [Rh(2)(PCy(3))(2)](2+) core. One carborane interacts with the metal core through three Rh-H-B bonds, while the other interacts through two Rh-H-B bonds and a direct Rh-B link. The electronic structure of this molecule is best described as having a dative Rh(I) --> Rh(III), d(8)--> d(6), interaction and a formal electron count of 16 and 18 electrons for the two rhodium centres respectively. Addition of H(2) to complexes 5a-c regenerate 3a-c. Addition of alkene (ethene or 1-hexene) to 5a-c or 3a-c results in dehydrogenative borylation, with 1, 2, and 3-B-vinyl substituted cages observed by ESI-MS: [closo-(RHC[double bond, length as m-dash]CH)(x)CB(11)H(12-x)](-)x = 1-3, R = H, C(4)H(9). Addition of H(2) to this mixture converts the B-vinyl groups to B-ethyl; while sequential addition of 4 cycles of ethene (excess) and H(2) to CH(2)Cl(2) solutions of 5a-c results in multiple substitution of the cage (as measured by ESI-MS), with an approximately Gaussian distribution between 3 and 9 substitutions. Compositionally pure material was not obtained. Complexes 4a-c do not lose H(2). Addition of tert-butylethene (tbe) to 4a gives the new complex Rh(P(i)Pr(3))(eta(2)-H(2)C=CH(t)Bu)(closo-CB(11)H(6)Br(6)) 6, characterised spectroscopically and by X-ray diffraction, which show coordination of the alkene ligand and bidentate coordination of the [closo-CB(11)H(6)Br(6)](-) anion. By contrast, addition of tbe to 4b or 4c results in transfer dehydrogenation to give the rhodium complexes Rh{PCy(2)(eta(2)-C(6)H(9))}(closo-CB(11)H(6)Br(6)) 7 and Rh{PCyp(2)(eta(2)-C(5)H(7))}(closo-CB(11)H(6)Br(6)) 9, which contain phosphine-alkene ligands. Complex has been characterised crystallographically. PMID:17955135

Molinos, Eduardo; Brayshaw, Simon K; Kociok-Köhn, Gabrielle; Weller, Andrew S

2007-11-14

361

Unraveling the formation of HCPH(X2A') molecules in extraterrestrial environments: crossed molecular beam study of the reaction of carbon atoms, C(3Pj), with phosphine, PH3(X1A1).  

PubMed

The reaction between ground state carbon atoms, C(3P(j)), and phosphine, PH3(X(1)A1), was investigated at two collision energies of 21.1 and 42.5 kJ mol(-1) using the crossed molecular beam technique. The chemical dynamics extracted from the time-of-flight spectra and laboratory angular distributions combined with ab initio calculations propose that the reaction proceeds on the triplet surface via an addition of atomic carbon to the phosphorus atom. This leads to a triplet CPH3 complex. A successive hydrogen shift forms an HCPH2 intermediate. The latter was found to decompose through atomic hydrogen emission leading to the cis/trans-HCPH(X(2)A') reaction products. The identification of cis/trans-HCPH(X(2)A') molecules under single collision conditions presents a potential pathway to form the very first carbon-phosphorus bond in extraterrestrial environments like molecular clouds and circumstellar envelopes, and even in the postplume chemistry of the collision of comet Shoemaker-Levy 9 with Jupiter. PMID:17428038

Guo, Y; Gu, X; Zhang, F; Sun, B J; Tsai, M F; Chang, A H H; Kaiser, R I

2007-05-01

362

Convergent modulation of singlet and triplet excited states of phosphine-oxide hosts through the management of molecular structure and functional-group linkages for low-voltage-driven electrophosphorescence.  

PubMed

The controllable tuning of the excited states in a series of phosphine-oxide hosts (DPExPOCzn) was realized through introducing carbazolyl and diphenylphosphine-oxide (DPPO) moieties to adjust the frontier molecular orbitals, molecular rigidity, and the location of the triplet excited states by suppressing the intramolecular interplay of the combined multi-insulating and meso?linkage. On increasing the number of substituents, simultaneous lowering of the first singlet energy levels (S(1)) and raising of the first triplet energy levels (T(1), about 3.0?eV) were achieved. The former change was mainly due to the contribution of the carbazolyl group to the HOMOs and the extended conjugation. The latter change was due to an enhanced molecular rigidity and the shift of the T(1) states from the diphenylether group to the carbazolyl moieties. This kind of convergent modulation of excited states not only facilitates the exothermic energy transfer to the dopants in phosphorescent organic light-emitting diodes (PHOLEDs), but also realizes the fine-tuning of electrical properties to achieve the balanced carrier injection and transportation in the emitting layers. As the result, the favorable performance of blue-light-emitting PHOLEDs was demonstrated, including much-lower driving voltages of 2.6?V for onset and 3.0?V at 100?cd?m(-2), as well as a remarkably improved E.Q.E. of 12.6%. PMID:23180464

Han, Chunmiao; Zhang, Zhensong; Xu, Hui; Xie, Guohua; Li, Jing; Zhao, Yi; Deng, Zhaopeng; Liu, Shiyong; Yan, Pengfei

2013-01-01

363

Application of 4,4,4-Trifluoro-1-(Biphenyl-4-yl)Butane-1,3-Dione as a Chelating Extractant in the Solvent Extraction and Separation of Light Lanthanoids in Combination with Phosphine Oxides.  

PubMed

The 4,4,4-trifluoro-1-(biphenyl-4-yl)butane-1,3-dione(HL) has been synthesized and its complexation properties in solution was examined. Mixed ligand chelate extraction of light trivalent lanthanoids (La÷Gd) from chloride medium at constant ionic strength µ = 0.1 into C6H6 with HL in combination with one of the three phosphine oxide compounds trioctylphosphine oxide(TOPO), tributylphosphine oxide(TBPO) or triphenyphosphine oxide(TPPO) was studied. The composition of the extracted species was established as LnL3 with HL alone and as LnL3 2S in the presence of TOPO and TBPO or LnL3 S with the mixture of HL-TPPO. The 28 values of the overall equilibrium constants were calculated. A synergic effect up to 103-104 was observed for the extraction of the above-mentioned lanthanoid ions with binary mixtures of extractants. The change of the synergistic agent causes a significant increase of the KL,S values in the order TBPO < TPPO < TOPO. The parameters of the extraction process were determined and the separation factors between two adjacent Ln(III) were calculated. PMID:24061883

Atanassova, Maria; Kaloyanova, Stefka; Deligeorgiev, Todor

2010-12-01

364

Bioinspired Hydrogenase Models: The Mixed-Valence Triiron Complex [Fe3(CO)7(?-edt)2] and Phosphine Derivatives [Fe3(CO)7–x(PPh3)x(?-edt)2] (x = 1, 2) and [Fe3(CO)5(?2-diphosphine)(?-edt)2] as Proton Reduction Catalysts  

PubMed Central

The mixed-valence triiron complexes [Fe3(CO)7–x(PPh3)x(?-edt)2] (x = 0–2; edt = SCH2CH2S) and [Fe3(CO)5(?2-diphosphine)(?-edt)2] (diphosphine = dppv, dppe, dppb, dppn) have been prepared and structurally characterized. All adopt an anti arrangement of the dithiolate bridges, and PPh3 substitution occurs at the apical positions of the outer iron atoms, while the diphosphine complexes exist only in the dibasal form in both the solid state and solution. The carbonyl on the central iron atom is semibridging, and this leads to a rotated structure between the bridged diiron center. IR studies reveal that all complexes are inert to protonation by HBF4·Et2O, but addition of acid to the pentacarbonyl complexes results in one-electron oxidation to yield the moderately stable cations [Fe3(CO)5(PPh3)2(?-edt)2]+ and [Fe3(CO)5(?2-diphosphine)(?-edt)2]+, species which also result upon oxidation by [Cp2Fe][PF6]. The electrochemistry of the formally Fe(I)–Fe(II)–Fe(I) complexes has been investigated. Each undergoes a quasi-reversible oxidation, the potential of which is sensitive to phosphine substitution, generally occurring between 0.15 and 0.50 V, although [Fe3(CO)5(PPh3)2(?-edt)2] is oxidized at ?0.05 V. Reduction of all complexes is irreversible and is again sensitive to phosphine substitution, varying between ?1.47 V for [Fe3(CO)7(?-edt)2] and around ?1.7 V for phosphine-substituted complexes. In their one-electron-reduced states, all complexes are catalysts for the reduction of protons to hydrogen, the catalytic overpotential being increased upon successive phosphine substitution. In comparison to the diiron complex [Fe2(CO)6(?-edt)], [Fe3(CO)7(?-edt)2] catalyzes proton reduction at 0.36 V less negative potentials. Electronic structure calculations have been carried out in order to fully elucidate the nature of the oxidation and reduction processes. In all complexes, the HOMO comprises an iron–iron bonding orbital localized between the two iron atoms not ligated by the semibridging carbonyl, while the LUMO is highly delocalized in nature and is antibonding between both pairs of iron atoms but also contains an antibonding dithiolate interaction.

2014-01-01

365

Elevating the triplet energy levels of dibenzofuran-based ambipolar phosphine oxide hosts for ultralow-voltage-driven efficient blue electrophosphorescence: from D-A to D-?-A systems.  

PubMed

A series of donor (D)-?-acceptor (A)-type phosphine-oxide hosts (DBF(x) POPhCz(n)), which were composed of phenylcarbazole, dibenzofuran (DBF), and diphenylphosphine-oxide (DPPO) moieties, were designed and synthesized. Phenyl ?-spacer groups were inserted between the carbazolyl and DBF groups, which effectively weakened the charge transfer and triplet-excited-state extension. As the result, the first triplet energy levels (T(1)) of DBF(x)POPhCz(n) are elevated to about 3.0 eV, 0.1 eV higher than their D-A-type analogues. Nevertheless, the electrochemical analysis and DFT calculations demonstrated the ambipolar characteristics of DBF(x)POPhCz(n). The phenyl ? spacers hardly influenced the frontier molecular orbital (FMO) energy levels and the carrier-transporting ability of the materials. Therefore, these D-?-A systems are endowed with higher T(1) states, as well as comparable electrical properties to D-A systems. Phosphorescent blue-light-emitting diodes (PHOLEDs) that were based on DBF(x)POPhCz(n) not only inherited the ultralow driving voltages (2.4 V for onset, about 2.8 V at 200 cd m(-2), and <3.4 V at 1000 cd m(-2)) but also had much-improved efficiencies, including about 26 cd A(-1) for current efficiency, 30 Lm W(-1) for power efficiency, and 13% for external quantum efficiency, which were more than twice the values of devices that are based on conventional unipolar host materials. This performance makes DBFDPOPhCz(n) among the best hosts for ultralow-voltage-driven blue PHOLEDs reported so far. PMID:23233457

Han, Chunmiao; Zhang, Zhensong; Xu, Hui; Li, Jing; Zhao, Yi; Yan, Pengfei; Liu, Shiyong

2013-01-21

366

Synthesis, characterization, and in vitro antitumor properties of tris(hydroxymethyl)phosphine copper(I) complexes containing the new bis(1,2,4-triazol-1-yl)acetate ligand.  

PubMed

The new sodium bis(1,2,4-triazol-1-yl)acetate ligand, Na[HC(CO(2))(tz)(2)], has been prepared in methanol solution by using 1,2,4-triazole, dibromoacetic acid, and NaOH. Treatment of the [Cu(CH(3)CN)(4)][PF(6)] acceptor with Na[HC(CO(2))(tz)(2)] or Na[HC(CO(2))[(pz(Me2))(2)] in the presence of the tris(hydroxymethyl)phosphine coligand in methanol/acetonitrile solutions produced unprecedented mononuclear copper(I) complexes of the [L(n)]Cu[P(CH(2)OH)(3)](2) (L(1), 2; L(2), 3) [(CH(3)CN)(2)Cu(P(CH(2)OH)(3))(2)]PF(6), 4. These compounds have been characterized by elemental analyses, FTIR, ESI-MS, and multinuclear (1H and 31P) NMR spectral data. The new copper(I) complexes were tested for their cytotoxic properties against a panel of several human tumor cell lines. The results reported here indicate that all the complexes showed in vitro antitumor activity similar or better than that of cisplatin, the most used metal-based antitumor drug. In particular, [HC(CO(2))(pz(Me2))(2)]Cu[P(CH(2)OH)(3)](2), 3 showed IC(50) values markedly lower than the reference compound against all tumor cell lines. Chemosensitivity tests performed on cisplatin sensitive and resistant cell lines have demonstrated that all these Cu(I) complexes were able to overcome cisplatin resistance, supporting the hypothesis of a different mechanism of action compared to that exhibited by the reference drug. Flow cytometric analysis on 2008 human ovarian carcinoma cells revealed that complex 3, chosen as the best candidate, induced a marked enlargement of both cell size and granularity, and a significant increase in the fraction of G2/M cells that, differently from cisplatin, was not accompanied by the appearance of a relevant sub-G1 fraction. Besides, no evidence of caspase-3 activation was detected in cells treated with complex 3. We hypothesize that the cytotoxic activity of the new copper(I) complex may be correlated to its ability to trigger paraptosis, a nonapoptotic mechanism of cell death. PMID:17149861

Marzano, Cristina; Pellei, Maura; Colavito, Davide; Alidori, Simone; Lobbia, Giancarlo Gioia; Gandin, Valentina; Tisato, Francesco; Santini, Carlo

2006-12-14

367

Chelating or bridging Pd(II) and Pt(II) metalloligands from the functional phosphine ligand N-(diphenylphosphino)-1,3,4-thiadiazol-2-amine. New heterometallic Pd(II)/Pt(II) and Pt(II)/Au(I) complexes.  

PubMed

The reaction of two equivalents of the functional phosphine ligand N-(diphenylphosphino)-1,3,4-thiadiazol-2-amine Ph2PNHC=NNCHS (2) with [PdCl2(NCPh)2] in the presence of NEt3 gives the neutral, P,N-chelated complex cis-[Pd(Ph2PN=CNN=CHS)2] ([Pd(2-H)2], 3b), which is analogous to the Pt(II) analogue cis-[Pt (Ph2PN=CNN=CHS)2] ([Pt(2-H)2], 3a) reported previously. These complexes function as chelating metalloligands when further coordinated to a metal through each of the CH-N atoms. In the resulting complexes, each endo-cyclic N donor of the thiadiazole rings is bonded to a different metal centre. Thus, the heterodinuclear palladium/platinum complexes cis-[Pt(Ph2PN=CNN=CHS)2PdCl2]([Pt(2-H)2·PdCl2], 4a) and cis-[Pd(Ph2PN=CNN=CHS)2PtCl2]([Pd(2-H)2·PtCl2], 4b) were obtained by reaction with [PdCl2(NCPh)2] and [PtCl2(NCPh)2], respectively. In contrast, reaction of 3a with [AuCl(tht)] occurred instead at the P-bound N atom, and afforded the platinum/digold complex cis-[Pt{Ph2PN(AuCl)=CNN=CHS}2] ([Pt(2-H)2(AuCl)2], 5). For comparison, reaction of 4a with HBF4 yielded cis-[Pt(Ph2PNH=CNN=CHS)2PdCl2](BF4)2([H24a](BF4)2, 6), in which the chelated PdCl2 moiety is retained. Complexes 3b, 4a·CH2Cl2, 4b·0.5C7H8, 5·4CHCl3 and 6 have been structurally characterized by X-ray diffraction. PMID:21505707

Zhang, Shuanming; Pattacini, Roberto; Braunstein, Pierre

2011-06-01

368

Insertion, coupling and elimination processes in the reactions of the unsaturated alkyl-bridged complexes [Mo?(??-C?H?)?(?-CH?R)(?-PCy?)(CO)?] (R = H, Ph) with isocyanides and secondary phosphines.  

PubMed

The methyl-bridged complex [Mo2Cp2(?-Me)(?-PCy2)(CO)2] (Cp = ?(5)-C5H5) reacted with stoichiometric amounts of CN(t)Bu at 243 K to give the C,O:C,O-bridged acyl complex [Mo2Cp2{?-C,O:C,O-C(O)Me}(?-PCy2)(CN(t)Bu)(CO)], which at room temperature slowly rearranges into its iminoacyl-bridged isomer [Mo2Cp2(?-C,N:C,N-MeCN(t)Bu)(?-PCy2)(CO)2]. In contrast, the C:O-bridged acyl complex [Mo2Cp2{?-C:O-C(O)Me}(?-PCy2)(CN(t)Bu)(CO)] was the major product obtained when the above reaction was carried out at room temperature. Density Functional Theory (DFT) was used to find the most likely structures of all these isomers, of which the iminoacyl complex was the absolute minimum. In contrast to the above reactions, up to three molecules of the ligand added rapidly to the methyl complex when using the aryl isocyanides CNR (R = o-C6H4Me, p-C6H4OMe), triggering the coupling between the methyl ligand and one of the cyclopentadienyl groups to give the corresponding methylcyclopentadiene derivatives [Mo2Cp(?(4)-C5H5Me)(?-PCy2)(CNR)3(CO)]. Carbonylation of the latter complex (R = o-C6H4Me) induced the displacement of the ?(4)-bound ligand, but also gave small yields of the hydride derivative [Mo2Cp(?(5)-C5H4Me)(?-H)(?-PCy2){CN(o-C6H4Me)}(CO)3] (Mo-Mo = 3.2467(5) Å), the latter resulting from a C-H cleavage in the methylcyclopentadiene ligand. The reaction of the title complexes with phosphines HPR (R' = Et, Ph) gave two major products: the corresponding aldehyde complexes [Mo2Cp2(?-PCy2)(?-PR){?(2)-C(O)HR}(CO)] (Mo-Mo = 2.8288(5) Å when R = CH2Ph and R' = Et) and the dicarbonyl complexes [Mo2Cp2(?-PCy2)(?-PR)(CO)2], these following from alternative reductive elimination processes, from hydrogen and either acyl or alkyl ligands, respectively. PMID:24699932

Alvarez, M Angeles; García, M Esther; García-Vivó, Daniel; Martínez, M Eugenia; Ramos, Alberto; Ruiz, Miguel A

2014-06-01

369

Combined DFT and experimental studies of C-C and C-X elimination reactions promoted by a chelating phosphine-alkene ligand: the key role of penta-coordinate Pd(II.).  

PubMed

A combined computational and experimental study of the coordination chemistry of phosphine-alkene ligand L1 (N-diphenylphosphino-7-aza-benzobicyclo[2.2.1]hept-2-ene) with Pd(0) and Pd(II) is presented. Experimentally it is established that ligand L1 promotes direct alkyl-alkyl and indirect alkyl-halide reductive elimination from Pd(II) species, affording the palladium(0) complex [Pd(?(2)-P,C-L1)2] (2) in each case. The effectiveness of L1 in promoting these reactions is attributed to the initial formation of a penta-coordinate intermediate [PdMe(X)(?(1)-P-L1)(?(2)-P,C-L1)] (X = Me, Cl) coupled with the ease with which it transforms to 2. From computation, a lower activation barrier for C(sp(3))-C(sp(3)) coupling and subsequent elimination has been computed for a stepwise associative pathway involving the initial formation of [PdMe2(?(1)-P-L1)(?(2)-P,C-L1)], compared to that computed for direct elimination from its parent, cis-[PdMe2(?(2)-P,C-L1)]. Moreover, the C(sp(3))-C(sp(3)) coupling reaction has been found to be primarily under thermodynamic control. It has also been demonstrated computationally that the methyl group of penta-coordinate [PdCl(Me)(?(1)-P-L1)(?(2)-P,C-L1)] is susceptible to nucleophilic attack by the phosphorus lone pair of a further equivalent of ligand L1, which proceeds through an SN2-like transition state. This initiates an unusual, indirect intermolecular reductive elimination process, resulting in the formation of equimolar quantities of the methyl phosphonium chloride salt of L1 and complex 2, in agreement with experimental observations. In contrast to the C(sp(3))-C(sp(3)) coupling, computation shows that this indirect C(sp(3))-Cl reductive elimination process is essentially under kinetic control. PMID:24710270

Estévez, Laura; Tuxworth, Luke W; Sotiropoulos, Jean-Marc; Dyer, Philip W; Miqueu, Karinne

2014-08-01

370

Stereodynamics of sterically crowded metal-phosphine complexes: trans-[(t-Bu){sub 2}P(l-Pr)]{sub 2}MCl{sub 2} [M = Pt(II) and Pd(II)]. One-dimensional dynamic and two-dimensional chemical exchange NMR studies, X-ray crystallographic studies, molecular conformation trapping, and molecular mechanics calculations  

SciTech Connect

By using complementary techniques including dynamic NMR (DNMR) spectroscopy, X-ray crystallography, molecular conformation trapping and molecular mechanics calculations, incisive pictures of the stereodynamics of two sterically crowded Pd(II) and Pt(II) complexes have been elucidated. X-ray crystallography shows that the molecular geometry in the only crystalline modification (P2{sub 1}/a space group) of trans-[(t-Bu){sub 2}P(i-Pr)]{sub 2}PdCl{sub 2} (1) has C{sub i} symmetry. The isopropyl groups are mutually anti; the dihedral angle between the two P-CH bonds is 180{degrees}. For the isopropyl group on each phosphine ligand, one methyl group is anti and the other gauche ot the palladium atom. There are significant torsions about Pd-P,P-(i-Pr) and P-(t-Bu) bonds including a dihedral angle between proximate P-CH and Pd-Cl bonds of 21.6{degrees}. On the basis of the hypotheses that (a) when placed in solution, the conformation of each phosphine ligand of 1 will adopt an essentially exclusive preference for that in the crystal and (b) the two phosphines act essentially independently of each other, four stable diastereomeric equilibrium conformations are predicted. In two diastereomeric conformations, the isopropyl groups are mutually syn with dihedral angles between the P-CH bonds of 44{degrees} (C{sub 2} symmetry) and 0{degrees} (C{sub s} symmetry). In the other two diastereomeric forms, the isopropyl groups are mutually anti with dihedral angles between the P-CH bonds of 136{degrees} (C{sub 2} symmetry) and 180{degrees} (C{sub i} symmetry). Two-dimensional {sup 31}P({sup 1}H) NMR chemical exchange spectroscopy in conjunction with theoretical simulations of the one-dimensional {sup 31}P({sup 1}H) and {sup 13}C({sup 1}H)DNMR spectra do reveal the presence of four diastereomeric equilibrium conformations and allow elucidation of the preferred conformational interconversion pathways. 32 refs., 8 figs., 1 tab.

DiMeglio, C.M.; Ahmed, K.J.; Luck, L.A.; Weltin, E.E. [Univ. of Vermont, Burlington, VT (United States)] [and others

1992-10-29

371

Reactions of Co 2(CO) 8 and of Co 2(CO) 6L (L = 3-pentyn-1-ol, 1,4-butyn-diol or 2-methyl-3-butyn-2-ol) with 2(diphenylphosphino)ethyl-trietoxysilane and tris(hydroxymethyl)phosphine for applications to new sol–gel materials  

Microsoft Academic Search

The complex Co2(CO)6[?-?2-(H3CCCCH2CH2OH)] (1) with the ligand 3-pentyn-1-ol (pol) has been synthesized following established procedures. Its structure has been determined by X-ray analysis. The complex Co2(CO)6(mbo) (mbo=2-methyl-3-butyn-2-ol, HCCC(CH3)2OH), (3), along with the already known Co2(CO)6(bud) (bud=1,4-butyn-diol, HOCH2CCCH2OH) (2), and Co2(CO)8 were reacted with 2(diphenylphosphino)ethyl-triethoxysilane [Ph2PCH2CH2Si(OCH2CH3)3] (dpts) and tris(hydroxymethyl)phosphine [P(CH2OH)3] (thp). With dpts, mono- and di-substituted complexes were obtained: these were

Fabio Carniato; Giorgio Gatti; Giuliana Gervasio; Domenica Marabello; Enrico Sappa; Andrea Secco

2009-01-01

372

Synthesis and properties of novel flame-retardant and thermally stable poly(amideimide) s from N,N? -(bicyclo[2,2,2]oct-7-ene-tetracarboxylic)-bis-L-amino acids and phosphine oxide moiety by two different methods  

Microsoft Academic Search

N,N?-(bicyclo[2,2,2]oct-7-ene-tetracarboxylic)-bis-L-amino acids3a-g were synthesized by the condensation reaction of bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride1 with two equimolars of Lalanine2a, L-valine2b, L-leucine2c, L-isoleucine2d, L-phenyl alanine2e, L-2-aminobutyric acid2f and L-histidine2g in an acetic acid solution. Seven new poly(amide-imide)s PAIs5a-g were synthesized through the direct polycondensation reaction of seven chiralN,N?-(bicyclo[2,2,2]oct-7-ene-tetracarboxylic)-bis-L-amino acids3a-g with bis(3-amino phenyl) phenyl phosphine oxide4 by two different methods: direct polycondensation in a medium

Khalil Faghihi; Mohsen Hajibeygi; Meisam Shabanian

2009-01-01

373

X-ray structural investigation of the pentanuclear carbonyl-phosphine cluster of platinum Pt/sub 5/(CO)(. mu. -/sub 2/-CO)/sub 5/(PPh/sub 3/)/sub 4/ in the form of a solvate with three benzene molecules  

SciTech Connect

An x-ray structural investigation of the pentanuclear platinum cluster with a carbonyl-phosphine ligand environment Pt/sub 5/(CO)/sub 6/(PPh/sub 3/)/sub 4/ x 3C/sub 6/H/sub 6/ has been carried out (diffractometer, lambdaMo, -120/sup 0/, 9412 reflections, least-squares method in the anisotropic approximation to R = 0.029). The crystals are triclinic, a = 13,454, b = 13.719, c = 24.261 A, ..cap alpha.. = 76.71, ..beta.. = 85.94, ..gamma.. 73.36/sup 0/, the space group is P anti 1, and Z = 2. The Pt/sub 5/ cluster is a tetrahedron with the fifth Pt atom located over one of the edges; the structure of the cluster is similar to that previously investigated by Barbier et al, which is not isomorphous to the solvate of the same compound with three toluene molecules.

Slovokhotov, Yu.L.; Struchkov, Yu.T.

1987-02-01

374

The coordination chemistry of perfluorovinyl substituted phosphine ligands, a crystallographic and spectroscopic study. Co-crystallisation of both cis- and trans-isomers of [PtCl2{P(i)pr2(CF=CF2)}2] within the same unit cell.  

PubMed

The coordination chemistry of the perfluorovinyl phosphines PEt2(CF=CF2), P(i)Pr2(CF=CF2), PCy,(CF=CF2) and PPh(CF=CF2)2 to rhodium(I), palladium(II), and platinum(II) centres has been investigated. The electronic properties of the ligands are estimated based on v(CO) and 1J(Rh-P) values. X-Ray diffraction data for the square-planar Pd(II) and Pt(II) perfluorovinyl-phosphine containing complexes allow estimates of the steric demand for the series of ligands PPh2(CF=CF2), PEt2(CF=CF2), P(i)Pr2(CF=CF2), PCy2(CF=CF2) and PPh(CF=CF2)2 to be determined. The (CF=CF2) fragment is found to be more electron withdrawing than (C6F5) yet sterically less demanding. These ligands therefore provide a range of electron-neutral to phosphite-like electronic properties combined with a range of steric demands. This study also reveals that short intramolecular interactions from the metal centre to the beta-fluorine atom cis to phosphorus of the CF=CF2 groups are observed in all-trans square planar complexes of the ligands. Unusually, the complex [PtCl2{P(i)Pr2(CF=CF2)}2] crystallises with both cis- and trans-isomers present in the unit cell. It appears that co-crystallisation of both isomers occurs in order to maximise fluorous regions in the crystal packing, and the extended structure displays short fluorine-fluorine contacts. The generation of mixed geometries seems to be a phenomenon of crystallisation, as solution phase NMR studies reveal the presence of only the trans-isomer. PMID:18399236

Barnes, Nicholas A; Brisdon, Alan K; Brown, F R William; Cross, Wendy I; Herbert, Christopher J; Pritchard, Robin G; Sadiq, Ghazala

2008-01-01

375

(4-Ethenylphen-yl)diphenyl-phosphine selenide.  

PubMed

In the title mol-ecule, C(10)H(17)PSe, the P atom has a distorted tetra-hedral environment resulting in an effective cone angle of 165°. The benzene ring makes dihedral angles of 70.04?(8) and 77.28?(8)° with the phenyl rings, while the dihedral angle between the phenyl rings is 62.95?(8)°. In the crystal, mol-ecules are linked by C-H?? inter-actions. PMID:22969582

Phasha, Zanele H; Makhoba, Sizwe; Muller, Alfred

2012-09-01

376

Cyanidotetra-kis-(trimethyl-phosphine)cobalt(I)  

PubMed Central

The title compound, [Co(CN)(C3H9P)4], was obtained as a product of the reaction of [Co(PMe3)4] with a molar equivalent of 2,6-difluoro­benzonitrile in diethyl ether. This compound is stable in the air for several hours, but rapidly decomposes at room temperature in solution. The cobalt(I) atom has s trigonal–bipyramidal coordination enviroment in which the cyano group and one of the PMe3 groups are in the axial positions.

Xu, Xiaofeng; Feng, Lei; Li, Xiaoyan

2011-01-01

377

40 CFR 721.6020 - Phosphine, dialkylyphenyl.  

Code of Federal Regulations, 2013 CFR

...and availability of MSDSs does not apply when an MSDS is not required under § 721.72(c). The provision...requiring placement of specific information in an MSDS does not apply when an MSDS is not required under § 721.72(c)....

2013-07-01

378

Selective Azide Oxidation of 1,2-Bis(diphenylphosphino)benzene and Related Ethylenebis(phosphines) to Asymmetric Multifunctional Phosphorus Ligands and Formation of Rhodium(I) Complexes of These Ligands. Structural Characterization of the Prototypical Ligand 1-(((Trimethylsilyl)imino)diphenylphosphorano)-2-(diphenylphosphino)benzene and Its Rhodium(I) Complex: 1-Ph(2)P=N(SiMe(3))C(6)H(4)-2-(Ph(2)P)Rh(CO)Cl.  

PubMed

Selective azide mono-oxidation of o-bis(phosphines) such as o-bis(diphenylphosphino)benzene and other bis(phosphines) with cis-substituents on a rigid backbone such as an ethylene structure occurs as the result of the steric control exerted during the azide oxidation (Staudinger) reaction process. The azides used were the trimethylsilyl, 4-cyanotetrafluorophenyl, benzyl, and diphenoxyphosphonyl azides. The prototypical ligand 1-Ph(2)P=N(SiMe(3))-2-(Ph(2)P)C(6)H(4), 2, has been structurally characterized. Crystal data for 2: crystal dimensions, 0.38 x 0.38 x 0.57 mm; space group, monoclinic, P2(1)/c, (No. 14); a = 11.093(5) Å, b = 14.898(5) Å, c = 18.811(2) Å, beta = 102.76(2) degrees, V = 3031 Å(3), Z = 4. Final R, R(w) and GOF values were 0.068, 0.074, and 1.92 respectively. The P=N-SiMe(3) angle was wide, 152.7(3) degrees, and the P=N bond length short (1.529(5) Å) relative to arylated iminophosphoranes but in keeping with the trends for silylated analogs. The iminophosphorane center can be selectively transformed with other agents in a Wittig type reaction converting the azides to the monooxide, monosulfide, etc. The iminophosphoranophosphines are also good complexing agents and the Rh(I) complex derived from 2, 1-Ph(2)P=N(SiMe(3))-C(6)H(4)-2-(Ph(2)P)Rh(CO)Cl, 15 was structurally characterized. Crystal data for 15: crystal dimensions, 0.32 x 0.44 x 0.66 mm; space group, monoclinic, P2(1)/c (No. 14); a = 13.793(3) Å, b = 12.622(11) Å, c = 20.436(6) Å, beta = 105.93(2) degrees, V = 3421.2 Å(3), Z = 4. Final R, R(w), and GOF values were 0.064, 0.061, and 1.45 respectively. The complex shows typical square planar geometry about Rh, a cis phosphine-CO relationship, and no exceptional steric crowding of the coordination site. PMID:11666644

Reed, Robert W.; Santarsiero, Bernard; Cavell, Ronald G.

1996-07-17

379

Complexes of Multifunctional Phosphorus Ligands. Rhenium(V) Complexes of the Multidentate Phenoxyphosphine Ligands Bis(o-trimethylsilyloxyphenyl)phenylphosphine and Tris(o-trimethylsilyloxyphenyl)phosphine. Stepwise Elimination of Me(3)SiX (X = Cl, OEt) from the Metal-Ligand System.  

PubMed

The silylated aryloxo ligands bis(o-silyloxyphenyl)phenylphosphine (abbreviated PhP{OT}(2)) and tris(o-trimethylsilyloxyphenyl)phosphine (abbreviated P{OT}(3), where T = Me(3)Si) were prepared. Complexation reactions with O=ReCl(2)(OEt)(PPh(3))(2) and O=ReCl(3)(PPh(3))(2) proceed by displacement of one PPh(3) and the subsequent stepwise replacement of the OEt and/or Cl substituents. The new complex Re(O)Cl(2)[kappa(2)-(P,O)-(PhP{O}{OT})](PPh(3)), formed by elimination of Me(3)SiOEt, exists in diastereomeric cis and trans forms. Elimination of a second equivalent of Me(3)SiCl gives Re(O)Cl[kappa(3)-(P,O,O)-(PhP{O}(2))](PPh(3)). Similarly P{OT}(3) converts Re(O)Cl(2)(OEt)(PPh(3))(2) to ReOCl(2)[kappa(2)-(P,O)-(P{O}{OT}(2))](PPh(3)) (5) (structurally characterized as 5.0.875CH(2)Cl(2)): crystal data; triclinic P&onemacr;, a = 14.302(4) Å, b = 18.734(2) Å, c = 17.639(4) Å, alpha = 80.950(12) degrees, beta = 80.12(2) degrees, gamma = 81.76(2) degrees, Z = 4. Final R(1) and wR(2) values are 0.0852 and 0.1525, respectively on F(o)(2) > 2sigma(F(o)(2)) data (or 0.1948 and 0.2019 on all data). The phenoxy phosphine ligand in 5 is bound via P and one O to Re. The P atoms are mutually cis to each other and to the terminal oxygen on Re. Two ortho-trimethylsiloxy substituted phenyl rings dangle from the coordinated phosphorus atom. Complex 5 can be converted to Re(O)Cl[kappa(3)-(P,O,O)-(P{O}(2){OT})](PPh(3)) (6) by treatment with PPN(+) Cl(-) and 6 was also obtained by direct reaction of Re(O)Cl(3)(PPh(3))(2) with P{OT}(3) at higher temperatures. The complex 6 has been structurally characterized: crystal data triclinic, P&onemacr;, a = 10.1509(6) Å, b = 12.1123(8) Å, c = 16.2142(14) Å, alpha = 97.851(7) degrees, beta = 94.852(7) degrees, gamma = 96.889(6) degrees, Z = 2. Final R(1) and wR(2) values were 0.0303 and 0.0721 on F(o)(2) > 2sigma(F(o)(2)) data (or 0.0348 and 0.0742 on all data). The phenoxyphosphine ligand in 6 is bound facially to Re through P and two of the phenoxy oxygens. The Ph(3)P group and terminal oxygen atoms are cis to the oxygen atoms of the phenoxy ligands and the Cl lies trans to P. One trimethylsiloxyphenol group dangles. Careful hydrolysis of 6 gave Re(O)Cl[kappa(3)-(P,O,O)-(P{O}(2){OH})](PPh(3)) which was also formed during complexation reactions in moist solvent. Solution (31)P{(1)H} NMR demonstrated cis- or trans-(P,P) geometry for the complexes, which was confirmed in the two aforementioned cases by structure determinations. PMID:11670861

Cavell, Ronald G.; Hilts, Robert W.; Luo, Hongyan; McDonald, Robert

1999-03-01

380

Development of an extractive spectrophotometric method for estimation of uranium in ore leach solutions using 2-ethylhexyl phosphonic acid-mono-2-ethylhexyl ester (PC88A) and tri-n-octyl phosphine oxide (TOPO) mixture as extractant and 2-(5-bromo-2-pyridylozo)-5-diethyl aminophenol (Br-PADAP) as chromophore  

NASA Astrophysics Data System (ADS)

An extractive spectrophotometric analytical method has been developed for the determination of uranium in ore leach solution. This technique is based on the selective extraction of uranium from multielement system using a synergistic mixture of 2-ethylhexyl phosphonic acid-mono-2-ethylhexyl ester (PC88A) and tri-n-octyl phosphine oxide (TOPO) in cyclohexane and color development from the organic phase aliquot using 2-(5-Bromo-2-pyridylazo)-5-diethyl aminophenol (Br-PADAP) as chromogenic reagent. The absorption maximum (?max) for UO22+-Br-PADAP complex in organic phase samples, in 64% (v/v) ethanol containing buffer solution (pH 7.8) and 1,2-cyclohexylenedinitrilotetraacetic acid (CyDTA) complexing agent, has been found to be at 576 nm (molar extinction coefficient, ?: 36,750 ± 240 L mol-1 cm-1). Effects of various parameters like stability of complex, ethanol volume, ore matrix, interfering ions etc. on the determination of uranium have also been evaluated. Absorbance measurements as a function of time showed that colored complex is stable up to >24 h. Presence of increased amount of ethanol in colored solution suppresses the absorption of a standard UO22+-Br-PADAP solution. Analyses of synthetic standard as well as ore leach a solution show that for 10 determination relative standard deviation (RSD) is <2%. The accuracy of the developed method has been checked by determining uranium using standard addition method and was found to be accurate with a 98-105% recovery rate. The developed method has been applied for the analysis of a number of uranium samples generated from uranium ore leach solutions and results were compared with standard methods like inductively coupled plasma emission spectrometry (ICPAES). The determined values of uranium concentrations by these methods are within ±2%. This method can be used to determine 2.5-250 ?g mL-1 uranium in ore leach solutions with high accuracy and precision.

Biswas, Sujoy; Pathak, P. N.; Roy, S. B.

2012-06-01

381

Development of an extractive spectrophotometric method for estimation of uranium in ore leach solutions using 2-ethylhexyl phosphonic acid-mono-2-ethylhexyl ester (PC88A) and tri-n-octyl phosphine oxide (TOPO) mixture as extractant and 2-(5-bromo-2-pyridylozo)-5-diethyl aminophenol (Br-PADAP) as chromophore.  

PubMed

An extractive spectrophotometric analytical method has been developed for the determination of uranium in ore leach solution. This technique is based on the selective extraction of uranium from multielement system using a synergistic mixture of 2-ethylhexyl phosphonic acid-mono-2-ethylhexyl ester (PC88A) and tri-n-octyl phosphine oxide (TOPO) in cyclohexane and color development from the organic phase aliquot using 2-(5-Bromo-2-pyridylazo)-5-diethyl aminophenol (Br-PADAP) as chromogenic reagent. The absorption maximum (?(max)) for UO(2)(2+)-Br-PADAP complex in organic phase samples, in 64% (v/v) ethanol containing buffer solution (pH 7.8) and 1,2-cyclohexylenedinitrilotetraacetic acid (CyDTA) complexing agent, has been found to be at 576 nm (molar extinction coefficient, ?: 36,750 ± 240 L mol(-1)cm(-1)). Effects of various parameters like stability of complex, ethanol volume, ore matrix, interfering ions etc. on the determination of uranium have also been evaluated. Absorbance measurements as a function of time showed that colored complex is stable up to > 24h. Presence of increased amount of ethanol in colored solution suppresses the absorption of a standard UO(2)(2+)-Br-PADAP solution. Analyses of synthetic standard as well as ore leach a solution show that for 10 determination relative standard deviation (RSD) is < 2%. The accuracy of the developed method has been checked by determining uranium using standard addition method and was found to be accurate with a 98-105% recovery rate. The developed method has been applied for the analysis of a number of uranium samples generated from uranium ore leach solutions and results were compared with standard methods like inductively coupled plasma emission spectrometry (ICPAES). The determined values of uranium concentrations by these methods are within ± 2%. This method can be used to determine 2.5-250 ?g mL(-1) uranium in ore leach solutions with high accuracy and precision. PMID:22381794

Biswas, Sujoy; Pathak, P N; Roy, S B

2012-06-01

382

Phosphine-free synthesis of high-quality reverse type-I ZnSe/CdSe core with CdS/CdxZn1 - xS/ZnS multishell nanocrystals and their application for detection of human hepatitis B surface antigen  

NASA Astrophysics Data System (ADS)

Highly photoluminescent (PL) reverse type-I ZnSe/CdSe nanocrystals (NCs) and ZnSe/CdSe/CdS/CdxZn1 - xS/ZnS core/multishell NCs were successfully synthesized by a phosphine-free method. By this low-cost, 'green' synthesis route, more than 10 g of high-quality ZnSe/CdSe/CdS/CdxZn1 - xS/ZnS NCs were synthesized in a large scale synthesis. After the overgrowth of a CdS/CdxZn1 - xS/ZnS multishell on ZnSe/CdSe cores, the PL quantum yields (QYs) increased from 28% to 75% along with the stability improvement. An amphiphilic oligomer was used as a surface coating agent to conduct a phase transfer experiment, core/multishell NCs were dissolved in water by such surface modification and the QYs were still kept above 70%. The as-prepared water dispersible ZnSe/CdSe/CdS/CdxZn1 - xS/ZnS core/multishell NCs not only have high fluorescence QYs but also are extremely stable in various physiological conditions. Furthermore, a biosensor system (lateral flow immunoassay system, LFIA) for the detection of human hepatitis B surface antigen (HBsAg) was developed by using this water-soluble core/multishell NCs as a fluorescent label and a nitrocellulose filter membrane for lateral flow. The result showed that such ZnSe/CdSe/CdS/CdxZn1 - xS/ZnS core/multishell NCs were excellent fluorescent labels to detect HBsAg. The sensitivity of HBsAg detection could reach as high as 0.05 ng ml - 1.

Shen, Huaibin; Yuan, Hang; Niu, Jin Zhong; Xu, Shasha; Zhou, Changhua; Ma, Lan; Li, Lin Song

2011-09-01

383

Phosphine-free synthesis of high-quality reverse type-I ZnSe/CdSe core with CdS/Cd(x)Zn(1 - x)S/ZnS multishell nanocrystals and their application for detection of human hepatitis B surface antigen.  

PubMed

Highly photoluminescent (PL) reverse type-I ZnSe/CdSe nanocrystals (NCs) and ZnSe/CdSe/CdS/Cd(x)Zn(1 - x)S/ZnS core/multishell NCs were successfully synthesized by a phosphine-free method. By this low-cost, 'green' synthesis route, more than 10 g of high-quality ZnSe/CdSe/CdS/Cd(x)Zn(1 - x)S/ZnS NCs were synthesized in a large scale synthesis. After the overgrowth of a CdS/Cd(x)Zn(1 - x)S/ZnS multishell on ZnSe/CdSe cores, the PL quantum yields (QYs) increased from 28% to 75% along with the stability improvement. An amphiphilic oligomer was used as a surface coating agent to conduct a phase transfer experiment, core/multishell NCs were dissolved in water by such surface modification and the QYs were still kept above 70%. The as-prepared water dispersible ZnSe/CdSe/CdS/Cd(x)Zn(1 - x)S/ZnS core/multishell NCs not only have high fluorescence QYs but also are extremely stable in various physiological conditions. Furthermore, a biosensor system (lateral flow immunoassay system, LFIA) for the detection of human hepatitis B surface antigen (HBsAg) was developed by using this water-soluble core/multishell NCs as a fluorescent label and a nitrocellulose filter membrane for lateral flow. The result showed that such ZnSe/CdSe/CdS/Cd(x)Zn(1 - x)S/ZnS core/multishell NCs were excellent fluorescent labels to detect HBsAg. The sensitivity of HBsAg detection could reach as high as 0.05 ng ml( - 1). PMID:21852741

Shen, Huaibin; Yuan, Hang; Niu, Jin Zhong; Xu, Shasha; Zhou, Changhua; Ma, Lan; Li, Lin Song

2011-09-16

384

Synthesis, structure, and thermochemistry of the formation of the metal-metal bonded dimers [Mo(mu-TeAr)(CO)3(PiP3)]2 (Ar = phenyl, naphthyl) by phosphine elimination from *Mo(TePh)(CO)3(PiPr3)2.  

PubMed

The complexes (*TeAr)Mo(CO)3(PiPr3)2 (Ar = phenyl, naphthyl; iPr = isopropyl) slowly eliminate PiPr3 at room temperature in a toluene solution to quantitatively form the dinuclear complexes [Mo(mu-TeAr)(CO)3(PiPr3)]2. The crystal structure of [Mo(mu-Te-naphthyl)(CO)3(PiPr3)]2 is reported and has a Mo-Mo distance of 3.2130 A. The enthalpy of dimerization has been measured and is used to estimate a Mo-Mo bond strength on the order of 30 kcal mol-1. Kinetic studies show the rate of formation of the dimeric chalcogen bridged complex is best fit by a rate law first order in (*TeAr)Mo(CO)3(PiPr3)2 and inhibited by added PiPr3. The reaction is proposed to occur by initial dissociation of a phosphine ligand and not by radical recombination of 2 mol of (*TeAr)Mo(CO)3(PiPr3)2. Reaction of (*TePh)Mo(CO)3(PiPr3)2, with L = pyridine (py) or CO, is rapid and quantitative at room temperature to form PhTeTePh and Mo(L)(CO)3(PiPr3)2, in keeping with thermochemical predictions. The rate of reaction of (*TeAr)W(CO)3(PiPr3)2 and CO is first-order in the metal complex and is proposed to proceed by the associative formation of the 19 e- radical complex (*TePh)W(CO)4(PiPr3)2 which extrudes a *TePh radical. PMID:17257007

Weir, John J; McDonough, James E; Fortman, George; Isrow, Derek; Hoff, Carl D; Scott, Brian; Kubas, Gregory J

2007-02-01

385

Synthesis and X-ray Structural Study on the Complexes of Silver(I) Halide with Tricyclohexylephosphine, Diphenyl-(2,4,6-trimethoxy)phenylphosphine, Phenyl-2,4,6-trimethoxyphenyl phosphine, and Tris(2,4,6-trimethoxy)phenylphosphine  

SciTech Connect

A diverse array of structures for the complexes of silver(I) halide with triphenylphosphine (PPh{sub 3}) has been studied. The complexes may be described as being of the type [AgX(PPh{sub 3}){sub n}] (X = Cl, Br or I). The value of n varies in the range of 1-3. This also indicates that the stoichiometry of the complexes is in the range of 1-3. The complex with stoichiometry 1:1 is a tetramer. There are two structural types of tetramer reported, termed cubane and step or chair. The cubane structure has been reported for [AgX(PPh{sub 3})]{sub 4} (X = Cl, Br or I), while the step structure has only been reported for [AgI(PPh{sub 3})]{sub 4}. The complex with stoichiometry 1:2 may be a monomer or a dimer. The monomer has a quasi trigonal planar structural type and has only been reported for [AgBr(PPh{sub 3}){sub 2}]. The dimer has been reported for [(PPh{sub 3}){sub 2}Ag({mu}-X){sub 2}Ag(PPh{sub 3}){sub 2}] (X = Cl or Br) with silver atom in the distorted tetrahedral environment. The complex with stoichiometry 1:3 has a distorted tetrahedral structural type and has been reported for [AgX(PPh{sub 3}){sub 3}] (X = Cl, Br or I). Changing PPh{sub 3} with more hindered ligand such as tricyclohexylephosphine (Pcy{sub 3}) or derivative of PPh{sub 3} such as diphenyl-2,4,6-trimethoxy(phenyl)phosphine (dpmp), phenyl-bis{l_brace}2,4,6-trimethoxy(phenyl){r_brace} phosphine (pdmp), or tris{l_brace}2,4,6-trimethoxy(phenyl){r_brace}phosphine (tmpp) may give complexes with various structural types but with lower range of stoichiometry. Synthesis and X-ray structural study of these complexes has been done with the results summarized below. Silver(I) halide and Pcy{sub 3} give complexes with stoichiometry 1:1 and 1:2. The complex with stoichiometry 1:1 is a dimer or cubane. The dimer is observed for [(Pcy{sub 3})Ag({mu}-X){sub 2}Ag(Pcy{sub 3})] (X = Cl or Br). The unusual dimer is observed for [(Pcy{sub 3})Ag({mu}-I){sub 2}({mu}-py)Ag(Pcy{sub 3})] where the pyridine ligand is bonded to two silver atoms. The cubane is observed for [AgI(Pcy{sub 3})]{sub 4}. The complex with stoichiometry 1:2 has a quasi trigonal planar structural type and has been observed for [AgX(Pcy{sub 3}){sub 2}] (X = Cl, Br, I). Silver(I) halide and dpmp give complexes with stoichiometry 1:1 and 1:2. The complex with stoichiometry 1:1 is a dimer and has been observed for [(dpmp)Ag({mu}-X){sub 2}Ag(dpmp)] (X = Cl, Br or I). The complex with stoichiometry 1:2 has a quasi trigonal planar structural type and has been observed for [AgX(dpmp){sub 2}] (X = Cl, Br, I). Silver(I) halide and pdmp also give complexes with stoichiometry 1:1 and 1:2. The complex with stoichiometry 1:1 is a dimer and has been observed for [(pdmp)Ag({mu}-X){sub 2}Ag(pdmp)] (X Cl, Br or I). The complex with stoichiometry 1:2 has a quasi trigonal planar structural type and has been observed for [AgX(pdmp){sub 2}] (X = Cl, Br, I). Silver(I) halide and tmmp only give complexes with stoichiometry 1:1. This complex is a monomer and has been observed for [AgX(tmpp)] (X = Cl or Br). In this complex the silver atom is in a quasi linear environment. Based on the bond lengths between silver and phosphorous atoms in the complexes obtained, it can be concluded that bulky ligands tend to give complexes with lower range of stoichiometry. In addition, the bulkier the ligand the longer the bond length between the silver and phosphorous atoms.

Effendy [Jurusan Kimia, FMIPA Universitas Negeri Malang, Jl. Surabaya 6 Malang 65145 (Indonesia); White, A. H. [Chemistry, School of Biomedical, Biomolecular, and Chemical Sciences, The University of Western Australia, 35 Stirling Highway, Crawley WA 6009 (Australia)

2008-03-17

386

Synthesis and X-ray Structural Study on the Complexes of Silver(I) Halide with Tricyclohexylephosphine, Diphenyl-(2,4,6-trimethoxy)phenylphosphine, Phenyl-2,4,6-trimethoxyphenyl phosphine, and Tris(2,4,6-trimethoxy)phenylphosphine  

NASA Astrophysics Data System (ADS)

A diverse array of structures for the complexes of silver(I) halide with triphenylphosphine (PPh3) has been studied. The complexes may be described as being of the type [AgX(PPh3)n] (X = Cl, Br or I). The value of n varies in the range of 1-3. This also indicates that the stoichiometry of the complexes is in the range of 1-3. The complex with stoichiometry 1:1 is a tetramer. There are two structural types of tetramer reported, termed cubane and step or chair. The cubane structure has been reported for [AgX(PPh3)]4 (X = Cl, Br or I), while the step structure has only been reported for [AgI(PPh3)]4. The complex with stoichiometry 1:2 may be a monomer or a dimer. The monomer has a quasi trigonal planar structural type and has only been reported for [AgBr(PPh3)2]. The dimer has been reported for [(PPh3)2Ag(?-X)2Ag(PPh3)2] (X = Cl or Br) with silver atom in the distorted tetrahedral environment. The complex with stoichiometry 1:3 has a distorted tetrahedral structural type and has been reported for [AgX(PPh3)3] (X = Cl, Br or I). Changing PPh3 with more hindered ligand such as tricyclohexylephosphine (Pcy3) or derivative of PPh3 such as diphenyl-2,4,6-trimethoxy(phenyl)phosphine (dpmp), phenyl-bis{2,4,6-trimethoxy(phenyl)} phosphine (pdmp), or tris{2,4,6-trimethoxy(phenyl)}phosphine (tmpp) may give complexes with various structural types but with lower range of stoichiometry. Synthesis and X-ray structural study of these complexes has been done with the results summarized below. Silver(I) halide and Pcy3 give complexes with stoichiometry 1:1 and 1:2. The complex with stoichiometry 1:1 is a dimer or cubane. The dimer is observed for [(Pcy3)Ag(?-X)2Ag(Pcy3)] (X = Cl or Br). The unusual dimer is observed for [(Pcy3)Ag(?-I)2(?-py)Ag(Pcy3)] where the pyridine ligand is bonded to two silver atoms. The cubane is observed for [AgI(Pcy3)]4. The complex with stoichiometry 1:2 has a quasi trigonal planar structural type and has been observed for [AgX(Pcy3)2] (X = Cl, Br, I). Silver(I) halide and dpmp give complexes with stoichiometry 1:1 and 1:2. The complex with stoichiometry 1:1 is a dimer and has been observed for [(dpmp)Ag(?-X)2Ag(dpmp)] (X = Cl, Br or I). The complex with stoichiometry 1:2 has a quasi trigonal planar structural type and has been observed for [AgX(dpmp)2] (X = Cl, Br, I). Silver(I) halide and pdmp also give complexes with stoichiometry 1:1 and 1:2. The complex with stoichiometry 1:1 is a dimer and has been observed for [(pdmp)Ag(?-X)2Ag(pdmp)] (X = Cl, Br or I). The complex with stoichiometry 1:2 has a quasi trigonal planar structural type and has been observed for [AgX(pdmp)2] (X = Cl, Br, I). Silver(I) halide and tmmp only give complexes with stoichiometry 1:1. This complex is a monomer and has been observed for [AgX(tmpp)] (X = Cl or Br). In this complex the silver atom is in a quasi linear environment. Based on the bond lengths between silver and phosphorous atoms in the complexes obtained, it can be concluded that bulky ligands tend to give complexes with lower range of stoichiometry. In addition, the bulkier the ligand the longer the bond length between the silver and phosphorous atoms.

Effendy; White, A. H.

2008-03-01

387

3[(dx2-y2,dxy)(pz)] excited state of binuclear copper(I) phosphine complexes: effect of copper-ligand and copper-copper interactions on excited state properties and photocatalytic reductions of the 4,4'-dimethyl-2,2'-bipyridinium ion in alcohols.  

PubMed

A comprehensive study of the structural and spectroscopic properties of two-, three-, and four-coordinate copper(I) complexes with aliphatic phosphine ligands is presented. All complexes described in this work are characterized by X-ray crystallography. The intramolecular Cu...Cu separations in [Cu2(dcpm)2]X2, [Cu2(dcpm)2-(CH3CN)2]X2, and [Cu2(dmpm)3]-(ClO4)2 (dcpm=bis(dicyclohexylphosphino)methane; dmpm=bis(dimethylphosphino)methane; X=ClO4- and PF6-) are in the range 2.639(2)-3.021(2) A. The anion...CuI interaction is weak, as evidenced by the nearest O...Cu separation of 2.558(6) A in [Cu2(dcpm)2](ClO4)2 and the closest Cu...F separation of 2.79(1) A in [Cu2(dcpm)2](PF6)2. The absorption bands of [Cu2(dcpm)2]X2 and [Cu2(dcpm)2(CH3CN)2]X2 (X=ClO4- and PF6-) at lambda max 307-311 nm in CH2Cl2 are assigned as 1[3d sigma* --> 4p sigma] transitions; this has been confirmed by resonance Raman spectroscopy. The triplet emissions in the visible region from these complexes exhibit long lifetimes and are sensitive to the environment. The lowest emissive excited state is tentatively ascribed as 3[(dx2-y2, dxy)(pz)] in nature. For [Cu2(dcpm)2]2+ salts in CH3CN, the emissive species is postulated to be [Cu2(dcpm)2(CH3CN)n]2+ (n > or = 3). Efficient photocatalytic reduction of MV2+ (4,4'-dimethyl-2,2'-bipyridinium) to MV+ in alcoholic solutions by using [Cu2(dcpm)2](PF6)2 or [Cu2(dppm)2(CH3CN)4](ClO4)2 (dppm=bis(diphenylphosphino)methane) as a catalyst has been observed. The addition of CH3CN or use of [Cu2(dmpm)3]-(ClO4)2 as a catalyst did not allow photocatalytic reduction processes to occur. PMID:12868420

Mao, Zhong Mao; Chao, Hsiu-Yi; Che, Chi-Ming; Fu, Wen-Fu; Cheung, Kung-Kai; Zhu, Nianyong

2003-06-16

388

Synthesis and reactivity studies of palladium(II) complexes containing the N-phosphorylated iminophosphorane-phosphine ligands Ph2PCH2P{=NP(=O)(OR)2}Ph2 (R=Et, Ph): application to the catalytic synthesis of 2,3-dimethylfuran.  

PubMed

Reactions of [PdCl2(COD)] with 1 equiv. of the iminophosphorane-phosphine ligands Ph2PCH2P{=NP(=O)(OR)2}Ph2 (R=Et, Ph) lead to the novel Pd(II) derivatives cis-[PdCl2(kappa2-(P,N)-Ph2PCH2P{=NP(=O)(OR)2}Ph2)] (R=Et, Ph). Pd-N bond cleavage readily takes place upon treatment of these species with a variety of two-electron donor ligands. By this way, complexes cis-[PdCl2(kappa1-(P)-Ph2PCH2P{=NP(=O)(OR)2}Ph2)(L)] (R=Et, L=CNtBu, CN-2,6-C6H3Me2, py, P(OMe)3, P(OEt)3; R=Ph, L=CNtBu, CN-2,6-C6H3Me2, py, P(OMe)3, P(OEt)3) have been synthesized in high yields. The addition of two equivalents of ligands to dichloromethane solutions of [PdCl2(COD)] results in the formation of complexes trans-[PdCl2(kappa1-(P)-Ph2PCH2P{=NP(=O)(OR)2}Ph2)2] (R=Et, Ph), which can be converted into the dicationic species [Pd(Ph2PCH2P{=NP(=O)(OR)2}Ph2)2][SbF6]2 (R=Et, Ph) by treatment with AgSbF6. Complex also reacts with CNtBu to afford trans-[Pd(kappa1(P)-Ph2PCH2P{=NP(=O)(OPh)2}Ph2)2(CNtBu)2][SbF6]2. The structures of and have been determined by single-crystal X-ray diffraction methods. In addition, the ability of these Pd(II) complexes to promote the catalytic cycloisomerization of (Z)-3-methylpent-2-en-4-yn-1-ol into 2,3-dimethylfuran has also been studied. PMID:17225896

Cadierno, Victorio; Díez, Josefina; García-Alvarez, Joaquín; Gimeno, José; Nebra, Noel; Rubio-García, Javier

2006-12-21

389

Ruthenium (II) phosphine/picolinate complexes as antimycobacterial agents.  

PubMed

The synthesis, characterization and the anti-Mycobacterium tuberculosis (MTB) activities of three ruthenium complexes containing the 2-pyridinecarboxylic acid anion (picolinate), with formulae cis- [Ru(pic)(dppm)(2)]PF(6) (1), cis- [Ru(pic)(dppe)(2)]PF(6) (2) and [Ru(pic)(2)(PPh(3))(2)] (3) [pic=2-pyridinecarboxylate; dppm=bis(diphenylphosphino)methane; dppe=1,2-bis(diphenylphosphino)ethane; PPh(3)=triphenylphosphine] are reported in this article. The complexes were characterized by elemental analysis, spectroscopic and electrochemical techniques. Their in vitro antimycobacterial activity was determinated as the Minimum Inhibitory Concentration (MIC) for MTB cell growth, measured by the REMA method. The best MICs were found for complexes (1) and (2), with values of 0.78 and 0.26 microg/mL, respectively. The results are comparable to or better than "first line" or "second line" drugs commonly used in the treatment of TB. PMID:19931948

Pavan, Fernando R; Poelhsitz, Gustavo Von; do Nascimento, Fábio B; Leite, Sergio R A; Batista, Alzir A; Deflon, Victor M; Sato, Daisy N; Franzblau, Scott G; Leite, Clarice Q F

2010-02-01

390

Retrievals of Jovian Tropospheric Phosphine from Cassini/CIRS.  

National Technical Information Service (NTIS)

On December 30th 2000, the Cassini-Huygens spacecraft reached the perijove milestone on its continuing journey to the Saturnian system. During an extended six-month encounter, the Composite Infrared Spectrometer (CIRS) returned spectra of the Jovian atmos...

P. G. Irwin P. Parrish T. Foucher S. B. Calcutt F. W. Taylor

2004-01-01

391

Recent Developments in the Chemistry of N Heterocyclic Phosphines  

Microsoft Academic Search

\\u000a This chapter gives a survey on five- and six-membered phosphorus–nitrogen heterocyclic compounds whose rings combine a phosphazene\\u000a (>N–P = N–) or phosphazane (>N–P(X)–N2 or C3 building block. Representatives contain structurally diverse species like aromatic 1,3,2-diazaphosphinines and (benzo)-1,3,2-diazaphospholes,\\u000a cationic counterparts of subvalent main-group carbene analogues like 1,3,2-diazaphospholenium ions and phosphenium-diketiminates,\\u000a and neutral heterocycles like 1,3,2-diazaphospholenes featuring unusual structures and reactivities. The

Dietrich Gudat

2010-01-01

392

Proteomic evaluation of adults of Rhyzopertha dominica resistant to phosphine  

Microsoft Academic Search

A proteomic study using a PH3-susceptible (RD2) and -resistant strain (CRD343) of Rhyzopertha dominica was undertaken to validate the relation between change of proteins and PH3 resistance. Protein expression levels were compared using PD-Quest program after two-dimensional polyacrylamide gel-electrophoresis. Comparing the intensity of proteins, 15 proteins decreased and 6 proteins were newly expressed in CRD343. After MALDI-TOF and LC–MS\\/MS analyses,

Byeoung-Soo Park; Byung-Ho Lee; Tae-Wan Kim; YongLin Ren; Sung-Eun Lee

2008-01-01

393

Phosphorus-31 NMR Spectra of Some Tertiary Phosphine Rhodium Compounds.  

National Technical Information Service (NTIS)

Phosphorus-31 nmr data are reported for trans-chlorocarbonylbis (tris-phenylphosphine) rhodium (I) and for three compounds of the type tri-chlorotris(Triorganophosphine) rhodium (III). The spectra unambiguously confirm the trans configurations for the rho...

S. O. Grim R. A. Ference

1966-01-01

394

Chiral allene-containing phosphines in asymmetric catalysis  

PubMed Central

Traditionally, ligands used in asymmetric catalysis have contained either stereogenic atoms or hindered single bonds (atropisomerism), or both. Here we demonstrate that allenes, chiral 1,2-dienes, appended with basic functionality can serve as ligands for transition metals. We describe an allene-containing bisphosphine that, when coordinated to Rh(I), promotes the asymmetric addition of aryl boronic acids to ?-keto esters with high enantioselectivity. Solution and solid-state structural analysis reveals that one olefin of the allene can coordinate to transition metals generating bi- and tri-dentate ligands.

Cai, Feng; Pu, Xiaotao; Qi, Xiangbing; Lynch, Vincent; Radha, Akella; Ready, Joseph M.

2011-01-01

395

Electrochemical Properties of Palladium and Platinum Phosphine Complexes.  

National Technical Information Service (NTIS)

The electrochemistry of 11 palladium (II) and platinum (II) complexes of the type ML2X2(L = P, N, or C-donor; X = Cl or I) was examined by cyclic voltammetry in nonaqueous solution. Electrochemical reduction was irreversible and was coupled with loss of X...

J. M. Calvert B. H. Berrie R. J. Nowak J. C. Cooper

1985-01-01

396

High-Temperature-Resistant Polymer Research.  

National Technical Information Service (NTIS)

During the quarter, 4-biphenyl(phenyl)phosphinic, phosphafluorinic, bis(trifluoromethyl)phosphinic, and bis(n-heptafluoropropyl)phosphinic acids and beryllium 4-bipheny(phenyl)phosphinate were prepared; and the reactions of bis(trifluoromethyl)phosphinic ...

1967-01-01

397

Activation of P C Bonds in Phosphines and Aromatic C H Bonds in Toluene by Phosphine Complexes of Dichloro- and Dimethylplatinum(II) in Hydrocarbon Media  

Microsoft Academic Search

According to GLC and 1H and 31P NMR data, lipophilic complexes of cis-dichloro- and cis-di- methylplatinum(II), PtX2(L)2 (X = Cl, L = PPh3 (I); X = Me, L = PPh3 (II); X = Cl, L = P(m-CH3C6H4)3 (III); X = Me, L = P(m-CH3C6H4)3 (IV)), II and III slowly react with toluene at 120 C to give products of activation

A. N. Vedernikov; A. G. Zazybin; A. B. Solomonov; B. N. Solomonov

398

The Reduction of a Nitrile (CN) Group by Sodium Borohydride. The Preparation of Phosphine--Amine and Phosphine--Iimidate Complesex of Tungsten Carbonyl.  

ERIC Educational Resources Information Center

Describes an experiment for advanced-level undergraduate students for extending student experiences involving recording and interpreting infrared (IR) and nuclear magnetic resonance (NMR) spectra from reactions of organometallic compounds. Experimental procedures, analyses and structural assignments, and suggestions for extension and modification…

Faust, Kristen E.; Storhoff, Bruce N.

1989-01-01

399

Paramagnetic Rh(III) complexes from reactions of phosphines with hydride-bridged and nonbridged rhodium phthalocyanine dimers: Metal-to-ligand charge transfer induced by phosphines  

SciTech Connect

The paramagnetic rhodium phthalocyanine complex (RPc)(PMe{sub 3}){sub 2}Rh (4) (RPc = dianion of 1,4,8,11,15,18,22,25-octa-n-pentylphthalocyanine) has been prepared by the reaction of trimethylphosphine (PMe{sub 3}) with hydride-bridged and nonbridged rhodium phthalocyanine dimers. The reaction of the {mu}-hydrido complex (RPcH)Rh({mu}-H)Rh(RPc) (5) (RPcH = RPc with one of its meso nitrogens protonated) with PMe{sub 3} at {minus}10 C produces (RPc)(PMe{sub 3})RhH (6), which further reacts with PMe{sub 3} to produce 4 and H{sub 2} at higher temperatures. If the solution of 6 is allowed to warm in the absence of free PMe{sub 3}, H{sub 2} is also liberated and 6 is converted to an equal number of moles of 4 and [(RPc)Rh]{sub 2}(PMe{sub 3}) (7). In contrast, the reaction of 5 with pyridine (py) produces (RPc)(py)-RhH (11), which does not react with additional pyridine. Alternatively, 4 is generated by the reaction of the Rh-Rh bonded dimer [(RPc)Rh]{sub 2} (1) with PMe{sub 3}. In this reaction, the formation of 7 as an intermediate may be shown by the titration of 1 with PMe{sub 3}. Complex 1 reacts with 4 to produce (RPc)Rh{sup {minus}} (10) and (RPc)(PMe{sub 3}){sub 2}-Rh{sup +} (9). A redox exchange between 4 and 9 ensues. The cobalt analogue of 4, i.e., (RPc)(PMe{sub 3}){sub 2}Co (12), was generated reversibly by the reaction of (RPc)Co (13) with PMe{sub 3} at low temperatures. The {sup 1}H NMR and the ESR spectra of 4, 12, and 13 indicate that while 13 is a metal-centered radical, 4 and 12 are best described as ligand-centered radicals.

Chen, M.J.; Utschig, L.M.; Rathke, J.W. [Argonne National Lab., IL (United States)] [Argonne National Lab., IL (United States)

1998-11-02

400

Chiral phosphine ligands derived from sugars6. syntheses and spectroscopic studies on rhodium complexes with a new type of chiral phosphines  

Microsoft Academic Search

Methyl 4,6-O-benzylidene-3-deoxy-3-(diphenylphosphino)-?-D-altropyranoside (1) and methyl 4,6-O-benzylidene-2-deoxy-2-(diphenylphosphino)-?-D-altropyranoside (bd2) were prepared from methyl 2,3-anhydro-4,6-O-benzylidene-?-D-mannopyranoside and methyl 2,3-anhydro-4,6-O-benzylidene-?-D-allopyranoside, respectively, via regioselective and stereospecific ring-opening reactions in high yields. Ligands 1 and 2 reacted with [{Rh(CO)2Cl}2] to give trans-[(P?)2Rh(CO)Cl] (3, P? = 1 ; 4, P? = 2). Compounds 1–4 have been characterized by elemental analyses, multinuclear NMR, IR and Raman, mass spectroscopic investigations.

Jicheng Shi; Daxu Wu; Tingbin Wen; Getan Lu; Qiutian Liu; Beisheng Rang

1996-01-01

401

Molecular dihydrogen and hydrido derivatives of ruthenium(II) complexes containing chelating ferrocenyl-based tertiary phosphine amine ligands and/or monodentate tertiary phosphine ligands  

SciTech Connect

Reactions of complexes of the type RuCl[sub 2](PPh[sub 3])(P-N) with H[sub 2] are reported, where P-N represents the chelating ferrocene-based ligands ([eta]-C[sub 5]H[sub 5])Fe([eta]-C[sub 5]H[sub 3](CHMeNMe[sub 2])PR[sub 2]-1,2) with R = i-Pr (the isoPFA ligand) or Ph (the PPFA ligand). Depending on the solvent(s) used, and absence or presence of added base, RuCl[sub 2](PPh[sub 3])(isoPFA) (2b) generates the dinuclear [eta][sup 2]-H[sub 2] complexes L[sub 2]([eta][sup 2]-H[sub 2])Ru([mu]-Cl)[sub 2]([mu]-H)Ru(H)(PPh[sub 3])[sub 2] where L[sub 2] = isoPFA (complex 3) or L[sub 2] = (PPh[sub 3])[sub 2] (complex 4). n-Butanol solutions of RuCl[sub 2](PPh[sub 3])(PPFA) (2a) under H[sub 2] also yield 4, as well as Ru(H)Cl[sub 2](PPh[sub 3])(PPFA[center dot]H)(BuOH), a zwitterionic species containing a protonated amine moiety stabilized by coordinated n-BuOH, which is likely intermediate in heterolytic cleavage of the H[sub 2]: the complex RuH(Cl)(PPh[sub 3])(isoPFA) (5), together with a hybrido carbonyl species, is isolated from methanol solutions of 2b. Complexes 2b, 3, 4, and 5 are characterized by X-ray crystallography; the mononuclear complexes 2b and 5 are orthorhombic with space groups F2dd and P2[sub 1]2[sub 1]2[sub 1], respectively. Variable-temperature [sup 1]H- and [sup 31]P-NMR data for 3 reveal fast exchange between the [eta][sup 2]-H[sub 2] and the [mu]-H at 20[degrees]C and a slower exchange of this system with the terminal hydride; corresponding data for 4 and its P(p-tolyl)[sub 3] analogue 7 show a faster exchange involving all the hydrogens. Activation parameters are determined for the exchange processes. 48 refs., 13 figs., 7 tabs.

Hampton, C.R.S.M.; Butler, I.R.; Cullen, W.R.; James, B.R. (Univ. of British Columbia, Vancouver (Canada)); Charland, J.P. (National Research Council, Ottawa, Ontario (Canada)); Simpson, J. (Univ. of Otago, Dunedin (New Zealand))

1992-12-23

402

Tris[3,5-bis-(trifluoro-meth-yl)phen-yl]phosphine oxide  

PubMed Central

In the title compound, C24H9F18OP, an intra­molecular C—H?O short contact generates a five-membered ring, producing an S(5) ring motif. The dihedral angles between the benzene rings are 57.68?(10), 77.80?(11) and 79.48?(10)°. Each of the six trifluoro­methyl substituents shows rotational disorder over two positions with refined site-occupany ratios of 0.64?(3)/0.36?(3), 0.649?(14)/0.351?(14), 0.52?(2)/0.48?(2), 0.545?(16)/0.455?(16), 0.774?(9)/0.226?(9) and 0.63?(5)/0.37?(5). The crystal structure is stabilized by inter­molecular C—H?O and C—H?F inter­actions.

Shawkataly, Omar bin; Pankhi, Mohd. Aslam A.; Mohamed-Ibrahim, Mohamed Ismail; Hamdan, M. Razak; Fun, Hoong-Kun

2009-01-01

403

Fungicidal Activity of Phosphinic Analogues of Amino Acids Involved in Methionine Metabolism  

Microsoft Academic Search

In medicine and agriculture, the necessity of rationally planning attempts to find for new biologically active chemical compounds because of a tendency towards a reduction in the rate of the introduction of new products [1]. The conventional approach, based on accidental discovery of new preparations with their subsequent chemical optimization, has proven to be inefficient. With respect to pesticides, it

Yu. N. Zhukov; N. A. Vavilova; T. I. Osipova; T. M. Voinova; E. N. Khurs; V. G. Dzhavakhia; R. M. Khomutov

2004-01-01

404

Variable Ag—O bonding patterns in silver cyclic amide tri-aryl-phosphine complexes  

Microsoft Academic Search

The solid-state structures of five new tri-arylphosphine silver cyclic amide complexes having a systematic variation in the ring structures have been resolved. Normal Ag—N bonding and variable, weaker Ag—O bonding interactions, which can be attributed to the ring modifications, form the basis of the bonding patterns. Reported here are the solid-state structures of silver complexes of tri-arylphosphine derivatives of silver

D. R. Whitcomb; M. Rajeswaran

2006-01-01

405

Contact doping of silicon wafers and nanostructures with phosphine oxide monolayers.  

PubMed

Contact doping method for the controlled surface doping of silicon wafers and nanometer scale structures is presented. The method, monolayer contact doping (MLCD), utilizes the formation of a dopant-containing monolayer on a donor substrate that is brought to contact and annealed with the interface or structure intended for doping. A unique feature of the MLCD method is that the monolayer used for doping is formed on a separate substrate (termed donor substrate), which is distinct from the interface intended for doping (termed acceptor substrate). The doping process is controlled by anneal conditions, details of the interface, and molecular precursor used for the formation of the dopant-containing monolayer. The MLCD process does not involve formation and removal of SiO(2) capping layer, allowing utilization of surface chemistry details for tuning and simplifying the doping process. Surface contact doping of intrinsic Si wafers (i-Si) and intrinsic silicon nanowires (i-SiNWs) is demonstrated and characterized. Nanowire devices were formed using the i-SiNW channel and contact doped using the MLCD process, yielding highly doped SiNWs. Kelvin probe force microscopy (KPFM) was used to measure the longitudinal dopant distribution of the SiNWs and demonstrated highly uniform distribution in comparison with in situ doped wires. The MLCD process was studied for i-Si substrates with native oxide and H-terminated surface for three types of phosphorus-containing molecules. Sheet resistance measurements reveal the dependency of the doping process on the details of the surface chemistry used and relation to the different chemical environments of the P?O group. Characterization of the thermal decomposition of several monolayer types formed on SiO(2) nanoparticles (NPs) using TGA and XPS provides insight regarding the role of phosphorus surface chemistry at the SiO(2) interface in the overall MLCD process. The new MLCD process presented here for controlled surface doping provides a simple yet highly versatile means for achieving postgrowth doping of nanometer scale structures and interfaces. PMID:23083376

Hazut, Ori; Agarwala, Arunava; Amit, Iddo; Subramani, Thangavel; Zaidiner, Seva; Rosenwaks, Yossi; Yerushalmi, Roie

2012-11-27

406

Linear alkaline earth metal phosphinate coordination polymers: synthesis and structural characterization.  

PubMed

Reaction of alkaline earth metal salts with diphenylphosphinic acid in dimethylformamide solvent afforded four coordination polymers: [Mg3(O2PPh2)6(DMF)2]·2DMF (I), [Ca(O2PPh2)2(DMF)2] (II), [Sr(O2PPh2)2(DMF)2] (III) and [Ba(O2PPh2)2(DMF)2] (IV) (where DMF is N,N-dimethylformamide). Single-crystal X-ray diffraction revealed that all four compounds produce linear chain structures in the solid state, with the Ca, Sr and Ba forming isostructural crystals. The bulk materials were characterized by FT-IR and (1)H NMR spectroscopy and elemental analyses. PMID:24892607

Rood, Jeffrey A; Huttenstine, Ashley L; Schmidt, Zachery A; White, Michael R; Oliver, Allen G

2014-06-01

407

O-Phenyl (cyclo-hexyl-amido)(p-tolyl-amido)-phosphinate  

PubMed Central

In the title mol­ecule, C19H25N2O2P, the P atom is bonded in a distorted tetra­hedral environment. The dihedral angle between the two phenyl rings is 89.09?(8)°. The methyl H atoms are disordered over two sets of sites with equal occupancy. The O atom of the P=O group acts as a double hydrogen-bond acceptor of the type (N—H)2?(O=)P—, forming R 2 2(8) rings which are further linked into chains along [010].

Sabbaghi, Fahimeh; Pourayoubi, Mehrdad; Karimi Ahmadabad, Fatemeh; Parvez, Masood

2011-01-01

408

Ruthenium(II) phosphine/diimine/picolinate complexes: inorganic compounds as agents against tuberculosis.  

PubMed

This paper describes the synthesis and characterization of four new ruthenium complexes containing 1,4 bis(diphenylphosphino)butane (dppb), 2-pyridinecarboxylic acid anion (pic) and the diimines [(2,2'-bipyridine (bipy), 4,4'-dimethyl-2,2'-bipyridine (Me-bipy), 4,4'-dichloro-2,2'-bipyridine (Cl-bipy) and 1,10-phenanthroline (phen) as ligands, with formulae [Ru(pic)(dppb)(bipy)]PF(6) (SCAR01), [Ru(pic)(dppb)(Me-bipy)]PF(6) (SCAR02), [Ru(pic)(dppb)(Cl-bipy)]PF(6) (SCAR03) and [Ru(pic)(dppb)(phen)]PF(6) (SCAR04). Additionally, the in vitro anti-Mycobacterium tuberculosis (MTB) activity, cytotoxicity and activity against in vitro infection of these complexes and two more complexes, cis-[Ru(pic)(dppe)(2)]PF(6) (SCAR05) and cis-[RuCl(2)(dppb)(bipy)] (SCAR06), and their free ligands are described and discussed. All compounds showed excellent MIC against MTB, low cytotoxicity and a selectivity index higher than 10. Also, all compounds showed significant intracellular inhibition and the compound SCAR05 showed a better activity than rifampin and SQ109. This is the first report of activity against in vitro infection of ruthenium compounds. PMID:21875763

Pavan, Fernando R; Poelhsitz, Gustavo V; Barbosa, Marilia I F; Leite, Sergio R A; Batista, Alzir A; Ellena, Javier; Sato, Leticia S; Franzblau, Scott G; Moreno, Virtudes; Gambino, Dinorah; Leite, Clarice Q F

2011-10-01

409

Privileged phosphine-based metal-organic frameworks for broad-scope asymmetric catalysis.  

PubMed

A robust and porous Zr metal-organic framework (MOF) based on a BINAP-derived dicarboxylate linker, BINAP-MOF, was synthesized and post-synthetically metalated with Ru and Rh complexes to afford highly enantioselective catalysts for important organic transformations. The Rh-functionalized MOF is not only highly enantioselective (up to >99% ee) but also 3 times as active as the homogeneous control. XAFS studies revealed that the Ru-functionalized MOF contains Ru-BINAP precatalysts with the same coordination environment as the homogeneous Ru complex. The post-synthetically metalated BINAP-MOFs provide a versatile family of single-site solid catalysts for catalyzing a broad scope of asymmetric organic transformations, including addition of aryl and alkyl groups to ?,?-unsaturated ketones and hydrogenation of substituted alkene and carbonyl compounds. PMID:24684238

Falkowski, Joseph M; Sawano, Takahiro; Zhang, Teng; Tsun, Galen; Chen, Yuan; Lockard, Jenny V; Lin, Wenbin

2014-04-01

410

A mechanistic alternative for the intramolecular hydroboration of homoallylic amine and phosphine borane complexes.  

PubMed

Intramolecular hydroboration is demonstrated starting from homoallylic amine boranes upon activation by iodine. The process involves a B-iodoborane complex as the intermediate and may occur via internal displacement of iodide by the alkene to generate a cationic borane-alkene pi-complex on the way to hydroboration products. The reaction can be carried out using a catalytic amount of iodine. PMID:12940716

Scheideman, Matthew; Shapland, Peter; Vedejs, Edwin

2003-09-01

411

Phosphine- and hydrogen-free: highly regioselective ruthenium-catalyzed hydroaminomethylation of olefins.  

PubMed

A highly regioselective ruthenium-catalyzed hydroaminomethylation of olefins is reported. Using easily available trirutheniumdodecacarbonyl an efficient sequence consisting of a water-gas shift reaction, hydroformylation of olefins, with subsequent imine or enamine formation and final reduction is realized. This novel procedure is highly practical (ligand-free, one pot) and economic (low catalyst loading and inexpensive metal). Bulk industrial as well as functionalized olefins react with various amines to give the corresponding tertiary amines generally in high yields (up to 92?%), excellent regioselectivities (n/iso>99:1), and full chemoselectivity in favor of terminal olefins. PMID:24861955

Gülak, Samet; Wu, Lipeng; Liu, Qiang; Franke, Robert; Jackstell, Ralf; Beller, Matthias

2014-07-01

412

Complexes between hypohalous acids and phosphine derivatives. Pnicogen bond versus halogen bond versus hydrogen bond  

NASA Astrophysics Data System (ADS)

The complexes of HOBr:PH2Y (Y = H, F, Cl, Br, CH3, NH2, OH, and NO2), HOCl:PH2F, and HOI:PH2F have been investigated with ab initio calculations at the MP2/aug-cc-pVTZ level. Four types of structures (1, 2, 3a, and 3b) were observed for these complexes. 1 is stabilized by an O⋯P pnicogen bond, 2 by a P⋯X halogen bond, 3a by a H⋯P hydrogen bond and a P⋯X pnicogen bond, and 3b by H⋯P and H⋯Br hydrogen bonds. Their relative stability is related to the halogen X of HOX and the substituent Y of PH2Y. These structures can compete with interaction energy of -10.22 ? -29.40 kJ/mol. The Hsbnd O stretch vibration shows a small red shift in 1, a small irregular shift in 2, but a prominent red shift in 3a and 3b. The Xsbnd O stretch vibration exhibits a smaller red shift in 1, a larger red shift in 2, but an insignificant blue shift in 3a and 3b. The Psbnd Y stretch vibration displays a red shift in 1 but a blue shift in 2, 3a, and 3b. The formation mechanism, stability, and properties of these structures have been analyzed with molecular electrostatic potentials, orbital interactions, and non-covalent interaction index.

Li, Qingzhong; Zhu, Hongjie; Zhuo, Hongying; Yang, Xin; Li, Wenzuo; Cheng, Jianbo

2014-11-01

413

Electron and hole transport in a wide bandgap organic phosphine oxide for blue electrophosphorescence  

NASA Astrophysics Data System (ADS)

We report blue phosphorescent organic light-emitting devices (OLEDs) using an ambipolar host, N-(4-diphenylphosphoryl phenyl) carbazole (MPO12), doped with iridium (III) bis[(4,6-difluorophenyl)-pyridinato-N,C2']picolinate (FIrpic). The external quantum efficiency and operating voltage is 9.1(+/-0.1)% and 4.8 V, respectively, measured at a brightness of 800 cd/m2 with no outcoupling enhancement. By varying the layer structure of the OLEDs, we show that MPO12 is capable of transporting both electrons and holes, in contrast to previous demonstrations using diphosphine oxides, which only transported electrons. The improved hole transport results in improved device efficiency.

Cai, Xiuyu; Padmaperuma, Asanga B.; Sapochak, Linda S.; Vecchi, Paul A.; Burrows, Paul E.

2008-02-01

414

High efficiency simple white phosphorescent organic light-emitting diodes using a phosphine oxide host.  

PubMed

Highly efficient simple white organic light-emitting diodes (WOLEDs) were fabricated using a mixed host of 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC) and 2,7-bis(diphenylphosphoryl)-9,9'-spirobi[fluorene] (SPPO13) in the light-emitting layer. A two layer WOLED structure of TAPC hole transport layer and TAPC:SPPO13 emitting layer was developed. Red and blue phosphorescent emitters were doped in the TAPC:SPPO13 mixed host emitting layer and a high quantum efficiency of 16.0% was obtained. In addition, the maximum power efficiency of the WOLEDs was 37.5 Im/W and color coordinate was (0.43, 0.41). The color coordinate could be kept stable irrespective of the luminance of the device. PMID:22629924

Jang, Sang Eok; Lee, Jun Yeob

2012-02-01

415

Efficient asymmetric hydrogenation of ?-acetamidocinnamates through a simple, readily available monodentate chiral H-phosphinate.  

PubMed

An air-stable, simple (R(P))-mentylbenzylphosphinate, readily available in large quantities, can efficiently induce the rhodium-catalyzed asymmetric hydrogenation of ?-acetamidocinnamates with high enantioselectivity (up to 99.6% ee). Intramolecular hydrogen bonding plays an important role in this asymmetric induction. PMID:24615995

Wang, Xiang-Bo; Goto, Midori; Han, Li-Biao

2014-03-24

416

Preparation and characterization of mixed amido, carboxylato or thiazolato carbonyl(phosphine)technetium(I) complexes  

Microsoft Academic Search

Summary The complex [Tc(PPh3)2(CO)3Cl] reacts with the lithium salt of amido-carboxylato- and thiazolato-derivatives to give the new complexes (Ar= C6H4Me-p or C6H4OMe-p), [Tc(PPh3)2(CO)2(amt1,2)] [amt1=anion of 2-(methylamino)thiazole; amt2=anion of 2-4-methoxyphenylamino(thiazole)] and [Tc(PPh3)2(CO)2- (R = Ph2CH, PhCH2 or CCl3). The compounds have been characterized by elemental analysis, and i.r. and1H n.m.r. spectra.

Andrea Marchi; Roberto Rossi; Adriano Duatti; Gian Luigi Zucchini; Luciano Magon

1986-01-01

417

Molecular electrostatic potential approach to determining the steric effect of phosphine ligands in organometallic chemistry.  

PubMed

A two-layer ONIOM(B3LYP/6-31G(d,p):UFF) quantum mechanics (QM)-molecular mechanics (MM) optimization of PR3 ligands, where the QM layer is always constructed as PH3, followed by molecular electrostatic potential (MESP) analysis of the QM layer is suggested as a simple and effective method for evaluating the steric effect of PR3 ligands. The subtle variations in the electron distribution that arise as a result of the steric bulkiness as well as the conformational changes in the substituent groups is well reflected in the value of the MESP minimum (Vmin) located in the QM region. In general, a sterically bulky group has always shown a more negative Vmin than a sterically less bulky group. The difference between the Vmin value of free PH3 and the Vmin value at the QM region of PR3 is used as a measure of the steric effect of the PR3 ligand. This value, designated as MESPsteric, showed a good linear correlation with the cone angle values as well as the average of the intervalence HPH angles found in the QM layer. Further, the difference between the Vmin value at the QM region of PR3 (an indicator of the steric effect) and the Vmin value of the completely optimized PR3 ligand (an indicator of the combined effect of steric and electronic effects) showed a good linear correlation with the Hammett Sigmasigmap constants, which further confirmed the present approach to understanding the steric effect separately from the electronic effect. PMID:16780319

Suresh, Cherumuttathu H

2006-06-26

418

INVESTIGATING THE DEAROMATIVE REARRANGEMENT OF BIARYL PHOSPHINE-LIGATED PD(II) COMPLEXES  

PubMed Central

A series of monoligated L•PdII(Ar)X complexes (L = dialkyl biarylphosphine) have been prepared and studied in an effort to better understand an unusual dearomative rearrangement previously documented in these systems. Experimental and theoretical evidence suggest a concerted process involving the unprecedented PdII-mediated insertion of an aryl group into an unactivated arene.

Milner, Phillip J.; Maimone, Thomas J.; Su, Mingjuan; Chen, Jiahao; Muller, Peter; Buchwald, Stephen L.

2012-01-01

419

Complexes between hypohalous acids and phosphine derivatives. Pnicogen bond versus halogen bond versus hydrogen bond.  

PubMed

The complexes of HOBr:PH2Y (Y=H, F, Cl, Br, CH3, NH2, OH, and NO2), HOCl:PH2F, and HOI:PH2F have been investigated with ab initio calculations at the MP2/aug-cc-pVTZ level. Four types of structures (1, 2, 3a, and 3b) were observed for these complexes. 1 is stabilized by an O?P pnicogen bond, 2 by a P?X halogen bond, 3a by a H?P hydrogen bond and a P?X pnicogen bond, and 3b by H?P and H?Br hydrogen bonds. Their relative stability is related to the halogen X of HOX and the substituent Y of PH2Y. These structures can compete with interaction energy of -10.22?-29.40kJ/mol. The HO stretch vibration shows a small red shift in 1, a small irregular shift in 2, but a prominent red shift in 3a and 3b. The XO stretch vibration exhibits a smaller red shift in 1, a larger red shift in 2, but an insignificant blue shift in 3a and 3b. The PY stretch vibration displays a red shift in 1 but a blue shift in 2, 3a, and 3b. The formation mechanism, stability, and properties of these structures have been analyzed with molecular electrostatic potentials, orbital interactions, and non-covalent interaction index. PMID:24878434

Li, Qingzhong; Zhu, Hongjie; Zhuo, Hongying; Yang, Xin; Li, Wenzuo; Cheng, Jianbo

2014-11-11

420

Chain-end-functionalized polyphosphazenes via a one-pot phosphine-mediated living polymerization.  

PubMed

A simple polymerization of trichlorophosphoranimine (Cl3 P = N-SiMe3 ) mediated by functionalized triphenylphosphines is presented. In situ initiator formation and the subsequent polymerization progress are investigated by (31) P NMR spectroscopy, demonstrating a living cationic polymerization mechanism. The polymer chain lengths and molecular weights of the resulting substituted poly(organo)phosphazenes are further studied by (1) H NMR spectroscopy and size exclusion chromatography. This strategy facilitates the preparation of polyphosphazenes with controlled molecular weights and specific functional groups at the ?-chain end. Such well-defined, mono-end-functionalized polymers have great potential use in bioconjugation, surface modification, and as building blocks for complex macromolecular constructs. PMID:24700544

Wilfert, Sandra; Henke, Helena; Schoefberger, Wolfgang; Brüggemann, Oliver; Teasdale, Ian

2014-06-01

421

Dichlorido(?-toluene)[tris-(4-methoxy-phen-yl)phosphine]ruthenium(II).  

PubMed

In the title compound, [RuCl(2)(C(7)H(8))(C(21)H(21)O(3)P)], the Ru(II) atom possesses a pseudo-octa-hedral geometry and the metrical parameters around the metallic core compare well with those of similar three-legged-piano-stool complexes. PMID:21201372

Wang, Lei; Zhou, Xiang-Ge; Li, Rui-Xiang

2008-01-01

422

Highly enantioselective Rh-catalysed hydrogenation of 1-alkyl vinyl esters using phosphine-phosphoramidite ligands.  

PubMed

MatPhos, a good mate for hard tasks: The asymmetric hydrogenation of 1-alkyl vinyl esters, thwarted so far by mediocre ee values and low activities, can now be achieved with MatPhos/Rh catalysts with ee values of 96-99% for a variety of substrates at low catalyst loadings (0.1-1 mol %) and under mild conditions (5-20 bar H2, room temperature). After hydrolysis, the corresponding chiral secondary alkyl alcohols can be obtained in high enantiopurities providing a general and practical route to this important product class. PMID:24027035

Konrad, Tina Maria; Schmitz, Pascal; Leitner, Walter; Franciò, Giancarlo

2013-09-27

423

High-spin manganese(II) complexes of an amido/bis(phosphine) PNP ligand.  

PubMed

Syntheses of several Mn complexes supported by a monoanionic amido/bis(phosphino) PNP ligand (PNP = [2-P(CHMe(2))(2)-4-MeC(6)H(3)](2)N) from anhydrous MnCl(2) are reported. Treatment of (PNP)Li (2) with MnCl(2) in tetrahydrofuran (THF) led to isolation of either (PNP)Mn(mu-Cl)(2)Li(THF)(2) (5) or (PNP)MnCl (6), depending on the workup. Reaction of 6 with 2 equiv of MeLi resulted in isolation of (PNP)Mn(mu-Me)(2)Li(THF)(2) (7) that is structurally similar to 5. Reduction of 6 in the presence of pyridine produced material analytically consistent with (PNP)Mn(py)(3) (8), whereas reduction in the presence of 2,2'-bipyridine gave fully characterized (PNP)Mn(bipy) (9). Compounds 5 and 7 display magnetic moments indicative of high-spin Mn(II) (S = 5/2). The magnetic moment of 9 (S = 2) was interpreted as an antiferromagnetic combination of a high-spin Mn(II) center and a singly reduced bipyridine ligand. Addition of a single CO ligand to 9 generated diamagnetic, low-spin (PNP)Mn(bipy)(CO) (10). Solid-state structures of 5, 7, 9, and 10 were determined by X-ray diffraction methods and used in conjunction with density functional theory studies to analyze the electronic nature of the (PNP)Mn complexes under study. PMID:20441168

Bacciu, Deborha; Chen, Chun-Hsing; Surawatanawong, Panida; Foxman, Bruce M; Ozerov, Oleg V

2010-06-01

424

Synthesis of diaryl ketones via a phosphine-free Fukuyama reaction.  

PubMed

The synthesis of unsymmetrical diaryl ketones via the Fukuyama coupling of thioesters and organozinc reagents is described. Typically, the synthesis of diaryl ketones using this methodology provides low yields. The simple complex, Pd(dba)(2), was found to convert a variety of aryl thioesters to diaryl ketones in good yields. PMID:22037521

Kunchithapatham, Kamala; Eichman, Chad C; Stambuli, James P

2011-12-21

425

Carbonyl Difluoride: Reactions with Metal-Phosphine Complexes. (Reannouncement with New Availability Information).  

National Technical Information Service (NTIS)

Carbonyl difluoride (COF2) is a versatile and nondestructive fluorine-transfer reagent as demonstrated by the ready introduction of fluorine into a variety of P-H, N-H or C-H containing compounds. Furthermore, metal oxides may be converted into metal fluo...

O. D. Gupta R. L. Kirchmeier J. M. Shreeve

1991-01-01

426

Electron and Hole Transport in a Wide Bandgap Organic Phosphine Oxide for Blue Electrophosphorecsence  

SciTech Connect

We report blue phosphorescent organic light-emitting devices (OLEDs) using an ambipolar host, N-(4-diphenylphosphoryl phenyl) carbazole (MPO12), doped with iridium (III) bis[4,6-difluorophenyl)-pyridinato-N,C2´]picolinate (FIrpic). The external quantum efficiency and operating voltage is 9.1±0.1% and 4.8 V, respectively, measured at a brightness of 800 cd/m2 with no outcoupling enhancement. By varying the layer structure of the OLEDs, we show that MPO12 is capable of transporting both electrons and holes, in contrast to previous demonstrations using diphosphine oxides, which only transported electrons. The improved hole transport results in improved device efficiency.

Cai, Xiuyu; Padmaperuma, Asanga B.; Sapochak, Linda S.; Vecchi, Paul A.; Burrows, Paul E.

2008-02-28

427

Inhibition of human folylpolyglutamate synthetase by diastereomeric phosphinic acid mimics of the tetrahedral intermediate  

PubMed Central

Phosphorus-containing pseudopeptides, racemic at the C-terminal ?-carbon, are potent mechanism-based inhibitors of folylpolyglutamate synthetase (FPGS). They are mimics of the tetrahedral intermediate postulated to form during FPGS-catalyzed biosynthesis of poly(?-L-glutamates). In the present paper, the FPGS inhibitory activity of each diastereomer coupled to three heterocycles is reported. The high Rf pseudopeptide containing the 5,10-dideazatetrahydropteroyl (DDAH4Pte) heterocycle is most potent (Kis = 1.7 nM). While the heterocyclic portion affects absolute FPGS inhibitory potency, the high Rf species is more potent in each pair containing the same heterocycle. This species presumably has the same stereochemistry as the natural folate polyglutamate, i.e., (L-Glu-?-L-Glu). Unexpectedly, the low Rf (presumed L-Glu-?-D-Glu) species are only slightly less potent (<30-fold) less potent than their diastereomers. Further study of this phenomenon comparing L-Glu-?-L-Glu and L-Glu-?-D-Glu dipeptide-containing FPGS substrates shows that <1% contamination of commercial D-Glu precursors by L-Glu may give misleading information if L-Glu-?-L-Glu substrates have low Km values.

McGuire, John J.; Bartley, David M.; Tomsho, John W.; Haile, William H.; Coward, James K.

2009-01-01

428

Theoretical mechanistic study of the formic acid decomposition assisted by a Ru(II)-phosphine catalyst.  

PubMed

A density functional theory (DFT) study of formic acid decomposition, catalyzed by a model of the trans-[Ru(TPPTS)?(H?O)?]²? complex, has been performed. A mechanism comprising two competitive catalytic cycles, which have as a common intermediate a monohydride ruthenium complex, has been hypothesized in literature on the basis of high pressure NMR experiments. To explain the observed increase in H? production rate during the process, it has been suggested by the same authors that the reaction occurs entering the second proposed cycle (Cycle 2), although none of the complexes assumed to be formed have been experimentally observed. To gain more insights into the reaction mechanism, a detailed investigation of both the proposed catalytic cycles has been carried out. To describe the energy profiles, different accurate computational protocols have been employed. Our computations reveal that molecular hydrogen cannot be produced more rapidly following cycle 2, since it requires a larger amount of energy to occur. Moreover, the release of molecular hydrogen has been found to be the step that limits the reaction rate in both cycles, instead of the CO? dissociation as hypothesized by the authors. PMID:24810464

Mazzone, Gloria; Alberto, Marta E; Sicilia, Emilia

2014-05-01

429

rac-[2-(Dicyclohexylphosphanyl)phenyl](phenyl)phosphinic diisopropyl-amide-borane hemihydrate.  

PubMed

In the title compound, C(30)H(48)BNOP(2)·0.5H(2)O, the water molecule is disordered about an inversion centre. Both phospho-rus atoms shows distortions in their tetra-hedral environments with the cyclo-hexyl substituents disordered over two orientations in a 0.851?(3):0.149?(3) occupancy ratio. The crystal structure is assembled via O-H?O inter-actions between pairs of phosphininc amide mol-ecules and water molecules, creating hydrogen-bonded dimers with graph-set R(2) (4)(8) along [001]. Weak C-H?O inter-actions are also observed. PMID:23424555

Evans, Stephen J; Renison, C Alicia; Williams, D Bradley G; Muller, Alfred

2013-02-01

430

Plasma-Sprayed Poly (Metal Phosphinate) Coatings for High Temperature Applications.  

National Technical Information Service (NTIS)

Pigmented and unpigmented diphenylphosphinates of chromium, zirconium, and zinc have been investigated as material for plasma-sprayed coatings. The aluminum-pigmented zirconyl diphenylphosphinate hydroxide system provided coatings having good adhesion, ha...

J. P. King H. D. Gillman

1977-01-01

431

Chain-End-Functionalized Polyphosphazenes via a One-Pot Phosphine-Mediated Living Polymerization  

PubMed Central

A simple polymerization of trichlorophosphoranimine (Cl3P = N–SiMe3) mediated by functionalized triphenylphosphines is presented. In situ initiator formation and the subsequent polymerization progress are investigated by 31P NMR spectroscopy, demonstrating a living cationic polymerization mechanism. The polymer chain lengths and molecular weights of the resulting substituted poly(organo)phosphazenes are further studied by 1H NMR spectroscopy and size exclusion chromatography. This strategy facilitates the preparation of polyphosphazenes with controlled molecular weights and specific functional groups at the ?-chain end. Such well-defined, mono-end-functionalized polymers have great potential use in bioconjugation, surface modification, and as building blocks for complex macromolecular constructs.

Wilfert, Sandra; Henke, Helena; Schoefberger, Wolfgang; Bruggemann, Oliver; Teasdale, Ian

2014-01-01

432

Cyclic decapeptide gramicidin S derivatives containing phosphines: novel ligands for asymmetric catalysis.  

PubMed

The cyclic peptide gramicidin S was used as a rigid template to provide novel peptide-based bisphosphine ligands for transition metal catalysis. Two bisphosphine-coordinated Rh(I) complexes allowed asymmetric hydrogenation with 10-52% ee and the corresponding Pd(II) analogues catalysed asymmetric allylic alkylation with 13-15% ee. PMID:23235486

Guisado-Barrios, Gregorio; Muñoz, Bianca K; Kamer, Paul C J; Lastdrager, Bas; van der Marel, Gijs; Overhand, Mark; Vega-Vázquez, Marino; Martin-Pastor, Manuel

2013-02-14

433

Bond cleavage reactions in oxygen and nitrogen heterocycles by a rhodium phosphine complex  

SciTech Connect

The reactions of (C[sub 5]Me[sub 5])Rh(PMe[sub 3])PhH with furan, 2,5-dimethylfuran, 2,3-dihydrofuran, dibenzofuran, pyrrole, 1-methylpyrrole, 2,5-dimethylpyrrole, 1,2,5-trimethylpyrrole, carbazole, 9-methylcarbazole, pyrrolidine, pyridine, 3,5-lutidine, 2,4,6-collidine, pyrazole, 3-methylpyrazole, and piperidine have been investigated. While the oxygen heterocycles give only C-H activation, the nitrogen heterocycles yield C-H and N-H insertion products. The chloro derivative (C[sub 5]Me[sub 5])Rh(PMe[sub 3])[2-(1-methylpyrrole)]Cl was found to crystallize in the monoclinic space group C2/c with a = 13.753 (6) A, b = 9.665 (5) A, c = 30.14 (2) A, [beta] = 99.77 (5)-[degree], Z = 8, and V = 3949 (4.1) A[sup 3] while (C[sub 5]Me[sub