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Phosphane Ligand (phosphane + ligand)

Distribution by Scientific Domains
Chemistry100%
Distribution within Chemistry
Organic Chemistry38%
General & Introductory Chemistry19%

Selected Abstracts

Copper-Catalyzed Hydrosilylation with a Bowl-Shaped Phosphane Ligand: Preferential Reduction of a Bulky Ketone in the Presence of an Aldehyde,

ANGEWANDTE CHEMIE, Issue 8 2010
Tetsuaki Fujihara Prof.
Sperriges zuerst: Ein hoch aktiver Kupferkatalysator mit einem schalenförmigen Phosphanliganden (bsp) vermittelt eine bislang einzigartige Reaktion: die Hydrosilylierung von sperrigen Ketonen in Gegenwart eines ungeschützten Aldehyds. [source]

ChemInform Abstract: Copper-Catalyzed Hydrosilylation with a Bowl-Shaped Phosphane Ligand: Preferential Reduction of a Bulky Ketone in the Presence of an Aldehyde.

CHEMINFORM, Issue 26 2010
Tetsuaki Fujihara
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

Bis(acetylido) Complexes of Ruthenium(II) Bearing Monodentate Phosphane Ligands

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 27 2008
Leslie D. Field
Abstract Terminal acetylenes react with cis -RuMe2(PMe3)4 to form the bis(acetylido) complexes cis/trans -Ru(C,CR)2(PMe3)4 in good yield. The structures of trans - 2 (R = Ph), cis - 3 (R = p -C6H4 -OMe), trans - 4 (R = p -C6H4 -Me), cis - 6 (R = Me), trans - 7 (R = SiMe3) and cis - 8 (R = H) were determined by X-ray crystallography. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]

Theoretical Studies on Metal,Metal Interaction and Intrinsic 1,3[,*(d),(s/p)] Excited States of Dinuclear d10 Complexes with Bridging Phosphane Ligands

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 5 2006
Qing-Jiang Pan
Abstract To explore the metal,metal interaction and spectroscopic properties, the ground- and excited-state structures of [M2(dpm)2]2+ [M = Ag (2), Cu (3), dpm = bis(diphosphanyl)methane] and their solvated species [M2(dpm)2]2+·(MeCN)2 were optimized by the MP2 and CIS methods, respectively. In the ground states, the calculated M,M distances and their corresponding M,M stretching frequencies for 2 and 3 indicate the presence of metallophilic attraction; there is strong N,Cu/Ag coordination in acetonitrile, which is different from the case in previous studies of [Au2(dpm)2]2+ (1). CIS calculations show that 2 and 3 have 1,3[,*(d),(s/p)] as their lowest-energy excited state, as is also the case for 1, confirmed by unrestricted MP2 calculations. On the basis of the CIS-optimized structures, the TD-DFT (B3LYP) method was employed to calculate the emission spectra of such complexes. For 3, the phosphorescent emissions were calculated at 424 and 514 nm in the solid state and acetonitrile, which is comparable to the experimental data of 475 and 480 nm, respectively. The comparison between the gas-phase and solution emissions for 1,3 reveals that the N,M coordination results in a large red-shift of the emission wavelength. Taking previous studies into account , we found that the M,M distances are linearly correlated with the M,M stretching frequencies for the dinuclear d10 complexes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

Diastereomeric Halfsandwich Rhenium Complexes Containing Hemilabile Phosphane Ligands

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 24 2004
Stefan Dilsky
Abstract The syntheses and some typical reactions of diastereomeric rhenium complexes [CpRe(NO)(CO){P(Ph)(R)(R,)}]BF4 (R = Me, Ph; R, = 2-C6H4OMe, CH2C4H3S, CH2C4H7O) (3a,e) are described. Reduction of the carbonyl ligand with NaBH4 in THF gave the corresponding methyl complexes [CpRe(NO){P(Ph)(R)(R,)}(CH3)] (4a,e). Acid treatment of the methyl complexes leads to liberation of methane and coordination of the additional donor site of the potentially bidentate phosphane ligand. Of the chelate complexes 5a,e, those with R, = 2-C6H4OMe (5a, d) decomposed in solution at room temperature. In donor solvents, the chelate ring opens giving the stable solvated complexes [CpRe(NO){P(Ph)(R)(R,)}](solvent)]BF4 (solvent = CH3CN, THF) (6b,e, 7d). The new compounds are thus suitable starting materials for the syntheses of diastereomeric rhenium complexes [CpRe(NO){P(Ph)(R)(R,)}(L)]BF4. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]

Syntheses of New Chiral Phosphane Ligands by Diastereoselective Conjugate Addition of Phosphides to Enantiomerically Pure Acceptor-Substituted Olefins from the Chiral Pool

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 15 2005
Burkhard Wiese
Abstract A variety of new chiral phosphanes were prepared by highly diastereoselective additions of phosphanes to ,,,-unsaturated carbonyl compounds and related acceptor-substituted olefins derived from myrtenal as ex chiral pool source. Monophosphanes with astereogenic as well as stereogenic phosphorus are described. In addition diphosphanes were prepared by a highly diastereoselective double conjugate addition of a secondary diphosphane. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source]

ChemInform Abstract: Biphasic Hydroformylation in Ionic Liquids: Interaction Between Phosphane Ligands and Imidazolium Triflate, Toward an Asymmetric Process.

CHEMINFORM, Issue 20 2008
Loic Leclercq
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

The Influence of Phosphane Ligands on the Versatility of Ruthenium,Indenylidene Complexes in Metathesis

CHEMISTRY - A EUROPEAN JOURNAL, Issue 30 2010
Julie Broggi Dr.
Abstract The aim of the present study is to develop readily available and stable pre-catalysts that could be easily prepared on large scale from simple starting materials. Based on the hypothesis that substitution of classical PCy3 with phosphanes of varying electron-donating properties could be a straightforward manner to improve catalytic activity, a methodical study dealing with the effect of phosphane fine-tuning in ruthenium,indenylidene catalysts was performed. Challenged to establish how the electronic properties of para -substituted phosphane ligands translate into catalyst activity, the versatile behaviour of these new ruthenium,indenylidene complexes was investigated for a number of metathesis reactions. [source]

Synthesis of the First Chiral Bidendate Bis(trifluoromethyl)phosphane Ligand through Stabilization of the Bis(trifluoromethyl)phosphanide Anion in the Presence of Acetone

CHEMISTRY - A EUROPEAN JOURNAL, Issue 35 2006
Berthold Hoge Priv.-Doz.
Abstract Lewis acid/Lewis base adduct formation of the P(CF3)2, ion and acetone leads to a reduced negative hyperconjugation and, therefore, limits the CF bond activation. The resulting increased thermal stability of the P(CF3)2, ion in the presence of acetone allows selective substitutions and enables the synthesis of the first example of a chiral, bidentate bis(trifluoromethyl)phosphane ligand: a DIOP derivative, [(2,2-dimethyl-1,3-dioxolane-4,5-diyl)bis(methylene)]bis(diphenylphosphane), in which the phenyl groups at the phosphorus atoms are replaced by strong electron-withdrawing trifluoromethyl groups. The resulting high electron-acceptor strength of the synthesized bidentate (CF3)2P ligand is demonstrated by a structural and vibrational study of the corresponding tetracarbonyl,molybdenum complex. The stabilization of the P(CF3)2, ion in the presence of acetone is based on the formation of a dynamic Lewis acid/Lewis base couple, (CF3)2PC(CH3)2O,. Although there is no spectroscopic evidence for the formation of the formulated alcoholate ion, the intermediate formation of (CF3)2PC(CH3)2O, could be proved through the reaction with (CF3)2PP(CF3)2, which yields the novel phosphane,phosphinite ligand (CF3)2PC(CH3)2OP(CF3)2. This ligand readily forms square-planar Pt(II) complexes upon treatment with solid PtCl2. [source]

Palladium-Catalyzed Suzuki,Miyaura Cross-Coupling Using Phosphinous Acids and Dialkyl(chloro)phosphane Ligands

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 8 2006
Christian Wolf
Abstract The use of eleven palladium complexes having monomeric and ,-chloro-bridged dimeric structures and either bulky dialkyl- and diarylphosphinous acid ligands (POPd, POPd-Br, POPd1, POPd2, POPd6, POPd7, Ph1-Phoxide) or dialkyl(chloro)phosphane ligands (PXPd, PXPd2, PXPd6, PXPd7) for Suzuki,Miyaura coupling reactions has been evaluated. Screening and optimization of catalyst loading, solvent, temperature, and base showed that excellent results can be obtained with electron-deficient and electron-rich aryl iodides, bromides, and chlorides in the presence of 2.5 mol-% of palladium,phosphinous acid POPd, (tBu2POH)2PdCl2, in 1,4-dioxane using cesium carbonate as base. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

Synthesis and Evaluation of a Broad Range of New Chiral (Aminoalkyl)phosphane Ligands for Asymmetric Hydrogen-Transfer Reduction of Prochiral Ketones

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 19 2003
Matthieu Léautey
Abstract Twenty new chiral (aminoalkyl)phosphane ligands have been prepared from four enantiomerically pure advanced chiral compounds. We describe their use for asymmetric hydrogen-transfer reduction of three prochiral ketones. Enantioselectivities up to 90% were obtained. We investigated the influence on the enantioselectivity of each part of these new (aminoalkyl)phosphane ligands. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source]

Tris(dibenzo[a,d]cycloheptenyl)phosphane: A Bulky Monodentate or Tetrapodal Ligand

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 18 2007
Urs Fischbach
Abstract The tetradendate phosphane tris(5H -dibenzo[a,d]cyclohepten-5-yl)phosphane (trop3P, 1) was synthesized from tris(trimethylsilyl)phosphane and 5-chloro-5H -dibenzo[a,d]cycloheptene. Sulfurization of 1 with elemental sulfur led to trop3P=S. Complexes of 1 with AgI, AuI, RhI, IrI, and PdII were prepared. The structures of trop3P (1), trop3P=S (2), [AgCl(trop3P)] (3), [Au(trop3P)(MeCN)]PF6 (5), [RhCl(trop3P)] (6) and [Pd(trop3P)(H2O)](OTf)2 (9) were determined by X-ray diffraction studies. In the coinage metal complexes, 1 serves as monodentate extremely bulky ,1 -phosphane ligand (cone angle ca. 250°). In the RhI, IrI, and PdII complexes, 1 acts as tetradendate ligand. CP MAS NMR spectroscopy shows that the span of the chemical shift tensor increases in 7, 6, and 9 in this order (, = 310 ppm, 410 ppm, 465 ppm) and contains two strongly deshielded components, which are responsible for the unusual high frequency isotropic shift of the 31P resonances. This property correlates inversely with the metal to olefin backbonding (M,C=Ctrop) and ,(31P) decreases with increasing M,C=Ctrop in the order 9 (, = 260 ppm) > 7 (, = 196 ppm) > 6 (, = 135 ppm) > 3 (, = ,30.9 ppm). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

Reactions of GaCp* with a Hemilabile Derivative of Rh6(CO)16 , Synthesis and Structural Characterization of Two Novel Heterometallic Clusters: Rh6(CO)13(,,,3 -Ph2PC2H3)(,3 -GaCp*) and Rh6(CO)13(,1 -Ph2PC2H3)(,3 -GaCp*)2

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 1 2007
Elena V. Grachova
Abstract The reaction of Rh6(CO)14(Ph2PCH=CH2) with a twofold excess of GaCp* (Cp* = C5Me5) affords two novel heterometallic clusters Rh6(CO)13(,,,3 -Ph2PC2H3)(,3 -GaCp*) (1) and Rh6(CO)13(,1 -Ph2PC2H3)(,3 -GaCp*)2 (2) in a moderate yield. The hemilabile behavior of coordinated diphenylvinylphosphane in the starting cluster allows the easy insertion of GaCp* into the cluster coordination sphere, which eventually gives the cluster 1 with face-bridging coordination of the gallium fragment and the phosphane ligand recoordinated in an edge-bridging position. The further substitution of the vinyl function in 1 for the second GaCp* ligand affords cluster 2, where recoordination of the double bond is blocked by steric hindrance from adjacent GaCp* fragments. Both clusters were structurally characterized by X-ray crystallography in the solid state and by IR and NMR spectroscopy in solution. Hemilability of diphenylvinylphosphane in 1 was independently confirmed by the cluster reaction with CO, which gives the Rh6(CO)14(,1 -Ph2PC2H3)(GaCp*) adduct (3) with the phosphane ligand only coordinated through the phosphorus atom. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

Reactions of K2[Fe(CO)3(PPh3)]: Reductive Sb,Sb Coupling with Ph2SbCl To Form trans -[Fe(CO)3(PPh3)(Sb2Ph4)] and Salt Metathesis with Me3SbCl2 To Yield trans -[Fe(CO)3(PPh3)(SbMe3)]

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 1 2005
Ingo-Peter Lorenz
Abstract In contrast to the ferrate K2[Fe(CO)4], the phosphane-substituted ferrate K2[Fe(CO)3(PPh3)] (1) reacts with the stibane derivative Ph2SbCl by metal-assisted reductive Sb,Sb coupling to give the distibane complex trans -[Fe(CO)3(PPh3)(Sb2Ph4)] (3). The distibane ligand in 3 is terminally ,1 -coordinated trans to the phosphane ligand. However, the stiborane derivative Me3SbCl2 reacts with 1 in a metathetical substitution reaction to form the monostibane complex trans -[Fe(CO)3(PPh3)(SbMe3)] (5). Both compounds have been characterized by spectroscopic (IR, NMR, MS), analytical (C, H) and X-ray diffraction analyses. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source]

Diastereomeric Halfsandwich Rhenium Complexes Containing Hemilabile Phosphane Ligands

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 24 2004
Stefan Dilsky
Abstract The syntheses and some typical reactions of diastereomeric rhenium complexes [CpRe(NO)(CO){P(Ph)(R)(R,)}]BF4 (R = Me, Ph; R, = 2-C6H4OMe, CH2C4H3S, CH2C4H7O) (3a,e) are described. Reduction of the carbonyl ligand with NaBH4 in THF gave the corresponding methyl complexes [CpRe(NO){P(Ph)(R)(R,)}(CH3)] (4a,e). Acid treatment of the methyl complexes leads to liberation of methane and coordination of the additional donor site of the potentially bidentate phosphane ligand. Of the chelate complexes 5a,e, those with R, = 2-C6H4OMe (5a, d) decomposed in solution at room temperature. In donor solvents, the chelate ring opens giving the stable solvated complexes [CpRe(NO){P(Ph)(R)(R,)}](solvent)]BF4 (solvent = CH3CN, THF) (6b,e, 7d). The new compounds are thus suitable starting materials for the syntheses of diastereomeric rhenium complexes [CpRe(NO){P(Ph)(R)(R,)}(L)]BF4. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]

Synthesis of (Vinylidene)- and (Cyclopropenyl)ruthenium Complexes Containing a Tris(pyrazolyl)borato (Tp) Ligand

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 23 2004
Yih-Hsing Lo
Abstract A convenient high-yield route to [Ru(C,C,Ph)(Tp)(PPh3)2] [2; Tp = HB(pz)3, pz = pyrazolyl] has been found through the intermediacy of [RuCl2(Hpz)2(PPh3)2] (1). This complex is readily obtained on treatment of [RuCl2(PPh3)3] with 2 equiv. of pyrazole in boiling THF. The molecular structures of complexes 1 and 2 have been confirmed by single-crystal X-ray diffraction analysis. A number of new cationic vinylidene complexes [Ru{=C=C(Ph)CH2R}(Tp)(PPh3)2]+ [3a, R = CN; 3b, R = HC=CH2; 3c, R = CH=C(CH3)2; 3d, R = Ph; 3e, R = C(O)OMe] have been prepared by electrophilic addition of organic halides to complex 2. The deprotonation reaction of 3a yields the cyclopropenyl complex 4a. One phosphane ligand of 4a is remarkably labile, being replaced by donor ligands L to yield diastereomeric mixtures of the cyclopropenyl complexes 5a,5d mostly in an approximate 4:1 ratio. The cyclopropenyl rings in 4a and 5a are susceptible to ring opening by I2. In addition, treatment of 4a with nBuNC in the presence of MeOH results in substitution of a phosphane ligand by nBuNC followed by protonation of the three-membered ring by MeOH. This is then followed by addition of methoxide to give the vinyl ether complex [Ru{C(OMe)=C(Ph)CH2CN}(Tp)(PPh3)(nBuNC)] (8a). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]

Synthesis of Benzomorphan Analogues by Intramolecular Buchwald,Hartwig Cyclization

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 2 2007
Anton S. Khartulyari
Abstract A new strategy toward the important class of benzomorphans is described. The key bond formation is based on an intramolecular Buchwald,Hartwig enolate arylation reaction. Thus, alkylation of piperidones with ortho -bromobenzyl bromides provides the necessary substrates. In the presence of a palladium catalyst, a sterically hindered phosphane ligand, and a base, carbon,carbon bond formation to tricyclic benzomorphan derivatives takes place. After removal of the N -protecting group, derivatization reactions are possible. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

Palladium-Catalyzed Preparation of Propargylic or Allenylic Sulfides from Propargyl Halides or Mesylate and Thiols

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 3 2004
Ken Tsutsumi
Abstract In the presence of a catalytic amount of Pd0 -dppe complex [dppe: 1,2-bis(diphenylphosphanyl)ethane], generated in situ from [Pd2(dba)3·CHCl3] and dppe, propargylic bromide 1a reacted with an equimolar amount of propanethiol at 60 °C in DMF to afford propargylic sulfide 2 in an excellent yield. The reaction occurs readily when carried out in the presence of the weak base triethylamine. The choice of both the phosphane, which is employed as the palladium atom's ligand, and the solvent have a remarkable effect on this reaction. We found that the optimum conditions for the reaction are those using a bidentate phosphane ligand (dppe) in a polar solvent (DMF). Compound 1a reacted smoothly with both aromatic (PhSH) and secondary thiols (CySH) in high yields. The reactions with thiols bearing functional groups (OH or Cl) proceeded selectively in good to moderate yields. Primary chlorides 1b,e were readily converted into their corresponding propargylic sulfides 7,10 in high yields. The Pd0 -dppe catalyst was ineffective in the reaction of the bromide 1g bearing a tBu group at the propargylic position, but the reaction of the corresponding mesylate 1h using the Pd0 -DIOP catalyst [DIOP = O -isopropylidene-2,3-dihydroxy-1,4-bis(diphenylphosphanyl)butane] at 100 °C afforded the product 11 in good yield. Allenylic sulfides were obtained from 1g,i. We suggest that a cationic ,3 -type complex may be a more reactive intermediate in this catalytic reaction than neutral ,1 - or ,3 -allenyl/propargylpalladium complexes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]

Access to Stereodefined Trisubstituted Alkenes via Rhodium-Catalyzed 1,4-Addition of Potassium Trifluoro(organo)- borates to Baylis,Hillman Adducts

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 3 2006
Laure Navarre
Abstract In the presence of a rhodium catalyst, unactivated Baylis,Hillman adducts reacted regioselectively with potassium trifluoro(organo)borates to afford stereodefined trisubstituted alkenes with good yields. This highly efficient reaction (aerobic conditions, low temperature, absence of added phosphane ligand) is believed to proceed via a 1,4-addition/,-hydroxy elimination mechanism. [source]

Synthesis of the First Chiral Bidendate Bis(trifluoromethyl)phosphane Ligand through Stabilization of the Bis(trifluoromethyl)phosphanide Anion in the Presence of Acetone

CHEMISTRY - A EUROPEAN JOURNAL, Issue 35 2006
Berthold Hoge Priv.-Doz.
Abstract Lewis acid/Lewis base adduct formation of the P(CF3)2, ion and acetone leads to a reduced negative hyperconjugation and, therefore, limits the CF bond activation. The resulting increased thermal stability of the P(CF3)2, ion in the presence of acetone allows selective substitutions and enables the synthesis of the first example of a chiral, bidentate bis(trifluoromethyl)phosphane ligand: a DIOP derivative, [(2,2-dimethyl-1,3-dioxolane-4,5-diyl)bis(methylene)]bis(diphenylphosphane), in which the phenyl groups at the phosphorus atoms are replaced by strong electron-withdrawing trifluoromethyl groups. The resulting high electron-acceptor strength of the synthesized bidentate (CF3)2P ligand is demonstrated by a structural and vibrational study of the corresponding tetracarbonyl,molybdenum complex. The stabilization of the P(CF3)2, ion in the presence of acetone is based on the formation of a dynamic Lewis acid/Lewis base couple, (CF3)2PC(CH3)2O,. Although there is no spectroscopic evidence for the formation of the formulated alcoholate ion, the intermediate formation of (CF3)2PC(CH3)2O, could be proved through the reaction with (CF3)2PP(CF3)2, which yields the novel phosphane,phosphinite ligand (CF3)2PC(CH3)2OP(CF3)2. This ligand readily forms square-planar Pt(II) complexes upon treatment with solid PtCl2. [source]

[FeFe]-Hydrogenase Models: Overpotential Control for Electrocatalytic H2 Production by Tuning of the Ligand ,-Acceptor Ability

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 25 2010
Fengwei Huo
Abstract In the search for synthetic competitive catalysts that function with hydrogenase-like capability, a series of (Pyrrol-1-yl)phosphane-substituted diiron complexes [(,-pdt)Fe2(CO)5L] [pdt = propanedithiolate, L = Ph2PPyr (2), PPyr3 (4); Pyr = pyrrolyl] and [(,-pdt)Fe2(CO)4L2] [L = Ph2PPyr (3), PPyr3 (5)] were prepared as functional models for the active site of Fe-only hydrogenase. The structures of these complexes were fully characterized by spectroscopy and X-ray crystallography. In the IR spectra the CO bands for complexes 2,5 are shifted to higher energy relative to those of complexes with "traditional" phosphane ligands, such as PPh3, PMe3, and PTA (1,3,5-triaza-7-phosphaadamantane), indicating that (pyrrol-1-yl)phosphanes are poor ,-donors and better ,-acceptors. The electrochemical properties of complexes 2,5 were studied by cyclic voltammetry in CH3CN in the absence and presence of the the weak acid HOAc. The reduction potentials of these complexes show an anodic shift relative to other phosphane-substituted derivatives. All of the complexes can catalyze proton reduction from HOAc to H2 in CH3CN at their respective FeIFe0 level. Complex 4 is the most effective electrocatalyst, which catalytically generates H2 from HOAc at ,1.66 V vs. Fc+/Fc with only ca. 0.2 V overpotential in CH3CN. [source]

Stereoselective Synthesis of the First Chatt-Type Bis(dinitrogen)-Molybdenum(0) Complex with a Tetraphosphane Ligand

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 21 2008
René Römer
Abstract The first Chatt-type Mo0 dinitrogen complex with a tetraphosphane ligand has been prepared and characterized by NMR as well as infrared and Raman spectroscopy. Importantly, the employed reaction route allows the stereospecific synthesis of this complex as trans -[Mo(N2)2(meso -prP4)] (prP4 = a tetraphos ligand with a central propylene bridge). The stereoselectivity in the reaction course is induced by the oxido-iodido-molybdenum(IV) precursor [Mo(O)I(prP4)]+ which directs both phenyl groups of the bridging P atoms of prP4 into a meso configuration. The paper establishes a general strategy to synthesize mononuclear Mo0 dinitrogen and related molybdenum complexes with multidentate phosphane ligands which has not been possible to date. Moreover, the obtained molybdenum tetraphos N2 complex should exhibit a higher thermodynamic stability in the reactions of the Chatt cycle of synthetic nitrogen fixation than the conventional bis(diphos) complexes, due to the linkage of the two diphosphane units by an alkyl bridge. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]

Decomposition Cascades of Dicoordinate Copper(I) Chalcogenides

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 33 2007
Heiko Jacobsen
Abstract Cu,E, Si,E, and Cu,P bond energies of R3PCuESiR3 and CuESiR3 complexes (E = O, S, Se) have been investigated using PBE density-functional calculations, and including empirical corrections for dispersive interactions (DFT-D). The bond energies have been used to investigate likely pathways of molecular decomposition. The energy profile for thermal decomposition is to a large degree independent of the nature of the phosphane ligands and silyl groups. Oxides, sulfides, and selenides have qualitatively the same thermal decomposition profile. Thermal decomposition is not likely to produce copper chalcogenide units CuE, but elemental copper Cu instead. Consideration of intermolecular van der Waals attraction suggests that the linear geometry of system tBu3PCuOSiPh3 as found in the crystal is most likely due to crystal packing and intermolecular forces.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

Cyanometalate Cages with Exchangeable Terminal Ligands

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 18 2007
Julie L. Boyer
Abstract The coordination chemistry of the unusual metallo-ligand Cs,[CpCo(CN)3]4[Cp*Ru]3 (Cs,Co4Ru3) is described with attention to the behavior of the ligand itself, its binding to Lewis-acidic metal cations, and its ability to stabilize catalytically relevant Ru,PPh3 fragments. A series of tests demonstrate that the "rim" [CpCo(CN)3], groups in Cs,Co4Ru3 are exchangeable. Upon treatment with [(MeC5H4)Co(CN)3], (Co,) Cs,Co4Ru3 undergoes vertex exchange to give Cs,Co4,xCo,xRu3. Similarly the cage is degraded by CO. Most convincing, Cs,Co4Ru3 reacts with PhNH3OTf to precipitate the polymer PhNH3CpCo(CN)3 and form the molecular box [Cs,Co4Ru4]+. Treatment of Cs,Co4Ru3 with [M(NCMe)x]PF6 (M = Cu, Ag) gave the Lewis acidic cages {Cs,[CpCo(CN)3]4[Cp*Ru]3M(NCMe)}PF6, which reacted with tertiary phosphane ligands to give adducts [Cs,Co4Ru3M(PPh3)]PF6. Lewis acidic octahedral vertices were installed using Fe, Ni, and Ru reagents. The boxes [Cs,Co4Ru3M(NCMe)3]2+ (M = Ni, Fe) formed readily from the reaction Cs,Co4Ru3 with [Ni(NCMe)6](BF4)2 and [Fe(NCMe)6](PF6)2. Displacement of the MeCN ligands gives [Cs,Co4Ru3Ni(9-ane-S3)](BF4)2. A series of boxes were prepared by the reaction of Cs,Co4Ru3 and RuCl2(PPh3)3, RuHCl(PPh3)3, and [(C6H6)Ru(NCMe)3](PF6)2. The derivative of the hydride, [Cs,Co4Ru3Ru(NCMe)(PPh3)2](PF6)2, was characterized crystallographically.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

Palladium-Catalyzed Suzuki,Miyaura Cross-Coupling Using Phosphinous Acids and Dialkyl(chloro)phosphane Ligands

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 8 2006
Christian Wolf
Abstract The use of eleven palladium complexes having monomeric and ,-chloro-bridged dimeric structures and either bulky dialkyl- and diarylphosphinous acid ligands (POPd, POPd-Br, POPd1, POPd2, POPd6, POPd7, Ph1-Phoxide) or dialkyl(chloro)phosphane ligands (PXPd, PXPd2, PXPd6, PXPd7) for Suzuki,Miyaura coupling reactions has been evaluated. Screening and optimization of catalyst loading, solvent, temperature, and base showed that excellent results can be obtained with electron-deficient and electron-rich aryl iodides, bromides, and chlorides in the presence of 2.5 mol-% of palladium,phosphinous acid POPd, (tBu2POH)2PdCl2, in 1,4-dioxane using cesium carbonate as base. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

Synthesis and Evaluation of a Broad Range of New Chiral (Aminoalkyl)phosphane Ligands for Asymmetric Hydrogen-Transfer Reduction of Prochiral Ketones

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 19 2003
Matthieu Léautey
Abstract Twenty new chiral (aminoalkyl)phosphane ligands have been prepared from four enantiomerically pure advanced chiral compounds. We describe their use for asymmetric hydrogen-transfer reduction of three prochiral ketones. Enantioselectivities up to 90% were obtained. We investigated the influence on the enantioselectivity of each part of these new (aminoalkyl)phosphane ligands. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source]

A general method to prepare monodentate phosphane ligands with mixed substituents

HETEROATOM CHEMISTRY, Issue 7 2009
Jennifer E. Phelps
Treatment of (2,2,-biphenylylene)- phosphorchloridite ester [(C12H8O2)PCl] (1) with C2F5Li yields (C12H8O2)PC2F52; treatment of 1 with Grignard reagents yields compounds of the type (C12H8O2)PR (R = iPr, 5; Et 6). In both cases, the 1,3-dioxepine ring formed when 2,2,-biphenol reacts with PCl3 to form 1 serves as a protecting group at the phosphorus atom; the ring allows the stepwise introduction of one substituent and prevents undesirable product mixtures associated with multiple substitutions at the phosphorus. Additional treatment of compounds 2, 5, and 6 with Grignard, alkyl-, or aryllithium reagents results in the formation of unsymmetrically substituted phosphanes. The use of (2,2,-biphenylylene)phosphorchloridite ester as a starting material for the preparation of electroneutral phosphanes of the type (Rf)PR2 and electron-poor phosphanes of the type (Rf)2PR is described. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 20:393,397, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20563 [source]

Asymmetric Hydrogenations (Nobel Lecture 2001)

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 1-2 2003
William
Abstract The start of the development of catalysts for asymmetric hydrogenation was the concept of replacing the triphenylphosphane ligand of the Wilkinson catalyst with a chiral ligand. With the new catalysts, it should be possible to hydrogenate prochiral olefins. Knowles and his co-workers were convinced that the phosphorus atom played a central role in this selectivity, as only chiral phosphorus ligands such as (R,R)-DIPAMP, whose stereogenic center lies directly on the phosphorus atom, lead to high enantiomeric excesses when used as catalysts in asymmetric hydrogenation reactions. This hypothesis was disproven by the development of ligands with chiral carbon backbones. Although the exact mechanism of action of the phosphane ligands is not incontrovertibly determined to this day, they provide a simple entry to a large number of chiral compounds. [source]

The Influence of Phosphane Ligands on the Versatility of Ruthenium,Indenylidene Complexes in Metathesis

CHEMISTRY - A EUROPEAN JOURNAL, Issue 30 2010
Julie Broggi Dr.
Abstract The aim of the present study is to develop readily available and stable pre-catalysts that could be easily prepared on large scale from simple starting materials. Based on the hypothesis that substitution of classical PCy3 with phosphanes of varying electron-donating properties could be a straightforward manner to improve catalytic activity, a methodical study dealing with the effect of phosphane fine-tuning in ruthenium,indenylidene catalysts was performed. Challenged to establish how the electronic properties of para -substituted phosphane ligands translate into catalyst activity, the versatile behaviour of these new ruthenium,indenylidene complexes was investigated for a number of metathesis reactions. [source]

Rhodium-Catalyzed Formation of Stereocontrolled Trisubstituted Alkenes from Baylis,Hillman Adducts

CHEMISTRY - A EUROPEAN JOURNAL, Issue 18 2009
Thomas Gendrineau
Abstract Efficient and general conditions for the formation of stereodefined trisubstituted alkenes by using the rhodium-catalyzed reaction of unactivated Baylis,Hillman adducts with either organoboronic acids or potassium trifluoro(organo)borates are reported (see scheme). We report here efficient and general conditions for the formation of stereodefined trisubstituted alkenes using the rhodium-catalyzed reaction of unactivated Baylis,Hillman adducts with either organoboronic acids and potassium trifluoro(organo)borates. The use of the [{Rh(cod)OH}2] precursor gave very fast coupling reactions under low catalyst loading, very mild reaction conditions (from room temperature up to 50,°C) and without the need of additional phosphane ligands. Based on the new reaction conditions, the reaction, originally limited to Baylis,Hillman adducts derived from esters, could be extended to a large variety of Baylis,Hillman adducts, bearing either keto, cyano or amido functionalities. Moreover, the reaction of Baylis,Hillman adducts bearing esters functionality was improved and could be conducted at lower temperature using lower catalyst loading. [source]