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A General Decomposition Pathway for Phosphine-Stabilized Metathesis Catalysts: Lewis Donors Accelerate Methylidene Abstraction
Sterically accessible Lewis donors are shown to accelerate decomposition during catalysis, for a broad range of Grubbs-class metathesis catalysts. These include benzylidene derivatives RuCl2(NHC)(PCy3)(=CHPh) (Ru-2: NHC = H2IMes, a; IMes, b; H2IPr, c; IPr, d; H2ITol, e) and indenylidene complexes RuCl2(NHC)(PCy3)(=C15H10) (NHC = H2IMes, Ru-2f; IMes, Ru-2g). All of these precatalysts form methylidene complex RuCl2(NHC)(=CH2) Ru-3 as the active species in metathesis of terminal olefins, and generate RuCl2(NHC)(PCy3)(=CH2) Ru-4 as the catalyst resting state. On treatment with a 10-fold excess of pyridine, Ru-4a and Ru-4b decomposed within minutes in solution at RT, eliminating [MePCy3]Cl A by net loss of three ligands (PCy3, methylidene, and one chloride), and a mesityl proton. In comparison, loss of A from Ru-4a in the absence of a donor requires up to 3 days at 55 °C. The σ-alkyl intermediate RuCl2(13CH2PCy3)(NHC) (py)2 resulting from nucleophilic attack of free PCy3 on the methylidene ligand was undetectable for the H2IMes system, but was spectroscopically observable for the IMes system. The relevance of this pathway to decomposition of catalysts Ru-2a-g was demonstrated by assessing the impact of pyridine on the in situ-generated methylidene species. Slow initiation (as observed for the indenylidene catalysts) did not protect against methylidene abstraction. Importantly, studies with Ru-4a and Ru-4b indicated that weaker donors (THF, MeCN, DMSO, MeOH, and even H2O) likewise promote this pathway, at rates that increase with donor concentration, and severely degrade catalyst productivity in RCM, even for a readily cyclized substrate. In all cases, A was the sole or major 31P-containing decomposition product. For DMSO, a first-order dependence of decomposition rates on DMSO concentration was established. This behavior sends a warning about the use of phosphine-stabilized metathesis catalysts in donor solvents, or with substrates bearing readily accessible donor sites. Addition of pyridine to RuCl2(H2IMes)(PCy3)(=CHMe) did not result in ethylidene abstraction, indicating that this decomposition pathway can be inhibited by use of substrates in which the olefin bears a β-methyl group.
McClennan, William L.,Rufh, Stephanie A.,Lummiss, Justin A. M.,Fogg, Deryn E.
p. 14668 - 14677
(2016)
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Catalytic synthesis of an unsymmetrical PNP-pincer-type phosphaalkene ligand
An unsymmetrical PNP-pincer-type phosphaalkene ligand, 2-(phospholanylmethyl)-6-(2-phosphaethenyl)pyridine (PPEP), has been prepared from 2,6-bis(2-phosphaethenyl)pyridine (BPEP) by intramolecular C-H addition/cyclization of the 2-phosphaethenyl group with a 2,4,6-tri-tert-butylphenyl substituent (CH=PMes). The reaction proceeds in hexane in the presence of a catalytic amount of [Pt(PCy3)2] (20 mol %) at 80 C in a sealed tube, giving PPEP in 32% isolated yield, along with byproduction of 2,6-bis(phospholanylmethyl)pyridine (BPMP) and a Pt(II) phosphanido complex (5). The PPEP ligand reacts with [Rh(μ-Cl)(C2H4)2]2 and [RuCl2(PPh3)3] to afford [RhCl(PPEP)] (6) and [RuCl2(PPh3)(PPEP)] (8), respectively. Complex 6 easily undergoes C-H addition/cyclization at the other CH=PMes group to afford the 2,6-bis(phospholanylmethyl)pyridine complex [RhCl(BPMP)] (7), whereas 8 is stable against C-H addition/cyclization. Treatment of 8 with tBuOK forms [RuCl(PPh3)(PPEP)] (9), coordinated with an unsymmetrical PNP-pincer-type phosphaalkene ligand containing a dearomatized pyridine unit (PPEP). The X-ray structures of 5 and 9 are reported. The reaction processes from BPEP to PPEP and to 5 are discussed based on NMR observations.
Taguchi, Hiro-Omi,Chang, Yung-Hung,Takeuchi, Katsuhiko,Ozawa, Fumiyuki
p. 1589 - 1596
(2015)
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A Lewis Base Nucleofugality Parameter, NFB, and Its Application in an Analysis of MIDA-Boronate Hydrolysis Kinetics
The kinetics of quinuclidine displacement of BH3 from a wide range of Lewis base borane adducts have been measured. Parameterization of these rates has enabled the development of a nucleofugality scale (NFB), shown to quantify and predict the leaving group ability of a range of other Lewis bases. Additivity observed across a number of series R′3-nRnX (X = P, N; R′ = aryl, alkyl) has allowed the formulation of related substituent parameters (nfPB, nfAB), providing a means of calculating NFB values for a range of Lewis bases that extends far beyond those experimentally derived. The utility of the nucleofugality parameter is explored by the correlation of the substituent parameter nfPB with the hydrolyses rates of a series of alkyl and aryl MIDA boronates under neutral conditions. This has allowed the identification of MIDA boronates with heteroatoms proximal to the reacting center, showing unusual kinetic lability or stability to hydrolysis.
García-Domínguez, Andrés,Gonzalez, Jorge A.,Leach, Andrew G.,Lloyd-Jones, Guy C.,Nichol, Gary S.,Taylor, Nicholas P.
supporting information

(2022/01/04)

A Mild One-Pot Reduction of Phosphine(V) Oxides Affording Phosphines(III) and Their Metal Catalysts
The metal-free reduction of a range of phosphine(V) oxides employing oxalyl chloride as an activating agent and hexachlorodisilane as reducing reagent has been achieved under mild reaction conditions. The method was successfully applied to the reduction of industrial waste byproduct triphenylphosphine(V) oxide, closing the phosphorus cycle to cleanly regenerate triphenylphosphine(III). Mechanistic studies and quantum chemical calculations support the attack of the dissociated chloride anion of intermediated phosphonium salt at the silicon of the disilane as the rate-limiting step for deprotection. The exquisite purity of the resultant phosphine(III) ligands after the simple removal of volatiles under reduced pressure circumvents laborious purification prior to metalation and has permitted the facile formation of important transition metal catalysts.
Kapu?niak, ?ukasz,Plessow, Philipp N.,Trzybiński, Damian,Wo?niak, Krzysztof,Hofmann, Peter,Jolly, Phillip Iain
supporting information
p. 693 - 701
(2021/04/06)

The Trityl-Cation Mediated Phosphine Oxides Reduction
Reduction of phosphine oxides into the corresponding phosphines using PhSiH3 as a reducing agent and Ph3C+[B(C6F5)4]? as an initiator is described. The process is highly efficient, reducing a broad range of secondary and tertiary alkyl and arylphosphines, bearing various functional groups in generally good yields. The reaction is believed to proceed through the generation of a silyl cation, which reaction with the phosphine oxide provides a phosphonium salt, further reduced by the silane to afford the desired phosphine along with siloxanes. (Figure presented.).
Landais, Yannick,Laye, Claire,Lusseau, Jonathan,Robert, Frédéric
supporting information
p. 3035 - 3043
(2021/05/10)

A process for preparing tertiary phosphines
The present invention relates to a process for the conversion of a tertiary phosphine oxide to the corresponding tertiary phosphine. The process has desired characteristics such as inexpensiveness, ease of handling, high efficiency, high yield and high conversion, as well as low environmental impact.
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Page/Page column 12; 13

(2020/05/21)

Direct and Scalable Electroreduction of Triphenylphosphine Oxide to Triphenylphosphine
The direct and scalable electroreduction of triphenylphosphine oxide (TPPO)-the stoichiometric byproduct of some of the most common synthetic organic reactions-to triphenylphosphine (TPP) remains an unmet challenge that would dramatically reduce the cost and waste associated with performing desirable reactions that are mediated by TPP on a large scale. This report details an electrochemical methodology for the single-step reduction of TPPO to TPP using an aluminum anode in combination with a supporting electrolyte that continuously regenerates a Lewis acid from the products of anodic oxidation. The resulting Lewis acid activates TPPO for reduction at mild potentials and promotes P-O over P-C bond cleavage to selectively form TPP over other byproducts. Finally, this robust methodology is applied to (i) the reduction of synthetically useful classes of phosphine oxides, (ii) the one-pot recycling of TPPO generated from a Wittig reaction, and (iii) the gram-scale reduction of TPPO at high concentration (1 M) with continuous product extraction and in flow at high current density.
Manabe, Shuhei,Sevov, Christo S.,Wong, Curt M.
p. 3024 - 3031
(2020/03/10)

A strong organic electron donor incorporating highly π-donating triphenylphosphonium ylidyl substituents
The π-electron donor strength of a triphenylphosphonium ylidyl group (Ph3PCH-) was explored through its substitution onto a bispyridinylidene (BPY) scaffold. Electrochemical studies revealed that the new triphenylphosphonium ylidyl-substituted BPY is the most reducing di-substituted derivative reported to date (E1/2 = -1.55 V vs. SCE). By using a previously established correlation between the redox potential of the substituted BPYs and the corresponding substituent, a Hammett constant for the Ph3PCH- group was determined (σp+ = -2.33), establishing it as the most donating neutral substituent currently quantified. The BPY is readily oxidized by hexachloroethane to produce the corresponding dicationic bipyridinium salt as a mixture of isomers owing to hindered Cylidyl-Cpyridyl bond rotation. In preliminary tests of the BPY as a reductant, dichlorotricyclohexylphosphorane and chlorodiphenylphosphine were reduced to the corresponding phosphine and diphosphine, respectively.
Burgoyne, Morgan M.,Macdougall, Thomas M.,Haines, Zachary N.,Conrad, Jordan W.,Calhoun, Larry A.,Decken, Andreas,Dyker, C. Adam
p. 9726 - 9733
(2019/12/02)

A Universally Applicable Methodology for the Gram-Scale Synthesis of Primary, Secondary, and Tertiary Phosphines
Although organophosphine syntheses have been known for the better part of a century, the synthesis of phosphines still represents an arduous task for even veteran synthetic chemists. Phosphines as a class of compounds vary greatly in their air sensitivity, and the misconception that it is trivial or even easy for a novice chemist to attempt a seemingly straightforward synthesis can have disastrous results. To simplify the task, we have previously developed a methodology that uses benchtop intermediates to access a wide variety of phosphine oxides (an immediate precursor to phosphines). This synthetic approach saves the air-free handling until the last step (reduction to and isolation of the phosphine). Presented herein is a complete general procedure for the facile reduction of phosphonates, phosphinates, and phosphine oxides to primary, secondary, and tertiary phosphines using aluminum hydride reducing agents. The electrophilic reducing agents (iBu)2AlH and AlH3 were determined to be vastly superior to LiAlH4 for reduction selectivity and reactivity. Notably, it was determined that AlH3 is capable of reducing the exceptionally resistant tricyclohexylphosphine oxide, even though LiAlH4 and (iBu)2AlH were not. Using this new procedure, gram-scale reactions to synthesize a representative range of primary, secondary, and tertiary phosphines (including volatile phosphines) were achieved reproducibly with excellent yields and unmatched purity without the need for a purification step.
Rinehart, N. Ian,Kendall, Alexander J.,Tyler, David R.
supporting information
p. 182 - 190
(2018/02/06)

Kinetics and Mechanism of Isocyanide-Promoted Carbene Insertion into the Aryl Substituent of an N-Heterocyclic Carbene Ligand in Ruthenium-Based Metathesis Catalysts
In situ IR spectroscopy was used to study the kinetics of addition of L = alkyl and aryl isocyanides to the Grubbs second-generation carbene complex Ru(H2IMes)(CHPh)(PCy3)Cl2 (H2IMes = 1,3-dimesityl-4,5-dihydroi
Griffiths, Justin R.,Hofman, Elan J.,Keister, Jerome B.,Diver, Steven T.
supporting information
p. 3043 - 3052
(2017/09/05)

Chemoselective Reduction of Phosphine Oxides by 1,3-Diphenyl-Disiloxane
Reduction of phosphine oxides to the corresponding phosphines represents the most straightforward method to prepare these valuable reagents. However, existing methods to reduce phosphine oxides suffer from inadequate chemoselectivity due to the strength of the P=O bond and/or poor atom economy. Herein, we report the discovery of the most powerful chemoselective reductant for this transformation to date, 1,3-diphenyl-disiloxane (DPDS). Additive-free DPDS selectively reduces both secondary and tertiary phosphine oxides with retention of configuration even in the presence of aldehyde, nitro, ester, α,β-unsaturated carbonyls, azocarboxylates, and cyano functional groups. Arrhenius analysis indicates that the activation barrier for reduction by DPDS is significantly lower than any previously calculated silane reduction system. Inclusion of a catalytic Br?nsted acid further reduced the activation barrier and led to the first silane-mediated reduction of acyclic phosphine oxides at room temperature.
Buonomo, Joseph A.,Eiden, Carter G.,Aldrich, Courtney C.
supporting information
p. 14434 - 14438
(2017/10/23)

Metal-Free Reduction of Phosphine Oxides, Sulfoxides, and N-Oxides with Hydrosilanes using a Borinic Acid Precatalyst
The general reduction of phosphine oxides, sulfoxides, and amine N-oxides was achieved by combining bis(2-chlorophenyl)borinic acid with phenylsilane. The reaction was shown to tolerate a wide range of substrates and could be performed under mild conditions, with only 2.5 mol % of the easily synthesized catalyst. Mechanistic investigations pointed to a key borohydride as the real catalyst and at bis(2-chlorophenyl)borinic acid as a precatalyst.
Chardon, Aurélien,Maubert, Orianne,Rouden, Jacques,Blanchet, Jér?me
p. 4460 - 4464
(2017/11/22)

Highly efficient reduction of tertiary phosphine oxides and sulfides with amine-assisted aluminum hydrides under mild conditions
Reduction of tertiary phosphine oxides and sulfides into the corresponding phosphines with amine-assisted aluminum hydrides has been studied. The method is characterized by mild conditions, short reaction time, high efficiency, and expanded substrate scope. The new method is an alternative to the currently used methods of reducing phosphine oxides or recycling phosphines engaged in organic reactions.
Yang, Shuyan,Han, Xinxin,Luo, Minmin,Gao, Jing,Chu, Wenxiang,Ding, Yuqiang
p. 1156 - 1160
(2015/06/30)

Donor-induced decomposition of the Grubbs catalysts: An intercepted intermediate
The σ-alkyl species RuCl2(CH2PCy3)(py)3 (3a) is intercepted on adding pyridine to the first-generation Grubbs catalyst 1a during RCM or to the isolated resting-state species RuCl2(PCy3)2(=CH2) (2a). Complex 3a is formed by pyridine-induced displacement of PCy3 and nucleophilic attack of the liberated PCy3 on the methylidene carbon. The rapid, near-quantitative conversion of 2a into 3a indicates that nucleophilic attack by PCy3 is the primary deactivating event. Once formed, 3a decomposes more slowly via several competing pathways. One such pathway involves elimination of the σ-alkyl ligand as [CH3PCy3]Cl (A), following proton and chloride abstraction. Observation of nearly 80% 3a during RCM by 1a in the presence of pyridine confirms the relevance of this behavior to metathesis and implicates the resting-state methylidene 2a as the vulnerable species, rather than the metallacyclobutane intermediate. Any donor capable of displacing PCy3 and stabilizing a five-coordinate methylidene adduct is predicted to trigger the same deactivation sequence, steric factors permitting.
Lummiss, Justin A. M.,McClennan, William L.,McDonald, Robert,Fogg, Deryn E.
supporting information
p. 6738 - 6741
(2015/02/19)

Synthesis and structure of the first heterodinuclear bis(borylene) complexes
We report a facile synthesis of the first heterodinuclear bis(borylene) complex by reaction of an iron bis(borylene) complex with [Pt(PCy 3)2], and its fully-reversible CO uptake and liberation reaction. The Royal Society of Chemistry.
Braunschweig, Holger,Ye, Qing,Damme, Alexander,Radacki, Krzysztof
supporting information
p. 7593 - 7595
(2013/08/28)

Reduction of phosphine oxides to phosphines with the InBr3/TMDS system
An efficient method for the reduction of phosphine oxide derivatives into their corresponding phosphines is described. The system InBr3/TMDS allows the reduction of different secondary and tertiary phosphine oxides as well as aliphatic and aromatic phosphine oxides.
Pehlivan, Leyla,Métay, Estelle,Delbrayelle, Dominique,Mignani, Gérard,Lemaire, Marc
supporting information; experimental part
p. 3151 - 3155
(2012/05/31)

Highly chemoselective metal-free reduction of phosphine oxides to phosphines
Unprecedented chemoselective reductions of phosphine oxides to phosphines proceed smoothly in the presence of catalytic amounts of specific Br?nsted acids. By utilizing inexpensive silanes, e.g., PMHS or (EtO)2MeSiH, other reducible functional groups such as ketones, aldehydes, olefins, nitriles, and esters are well-tolerated under optimized conditions.
Li, Yuehui,Lu, Liang-Qiu,Das, Shoubhik,Pisiewicz, Sabine,Junge, Kathrin,Beller, Matthias
p. 18325 - 18329
(2013/01/15)

METHOD FOR SYNTHESIZING CYCLOHEXYL-SUBSTITUTED PHOSPHINES
The present invention relates to a process for preparing cyclohexyl-substituted phosphines. The invention further relates to a process for preparing cyclohexyl-substituted phosphine oxides which can be used as intermediates in the preparation of cyclohexyl-substituted phosphines.
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(2010/06/16)

Radical synthesis of trialkyl, triaryl, trisilyl and tristannyl phosphines from P4
A reaction scheme has been devised according to 3 RX + 3 Ti(iii) + 0.25 P4 → PR3 + 3 XTi(iv), wherein RX = PhBr, CyBr, Me3SiI or Ph3SnCl, with contrasting results in the case of more hindered RX. The scheme accomplishes the direct radical functionalization of white phosphorus without the intermediacy of PCl3.
Cossairt, Brandi M.,Cummins, Christopher C.
supporting information; experimental part
p. 1533 - 1536
(2010/10/03)

Use of phosphonium salts in coupling reactions and process for their manufacture
The object of the present invention is the use of phosphonium salts in coupling reactions, and a method for their presentation.
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Page/Page column 6; 9-10

(2009/02/10)

An acidity scale of tetrafluoroborate salts of phosphonium and iron hydride compounds in [D2]dichIoromethane
Equilibrium constants (K) for reactions between acids and the conjugate base forms of a number of phosphonium salts, [HPR3][BF4], and iron hydrides, [Fe(CO)3H(PR3)2][BF 4], in CD2Cl2 have been determined by means of 31P and 1H NMR spectroscopy at 20°C. The anchor compound chosen for pKCD2Cl2 determinations was [HPCy 3][BF4] with a pKCD2Cl2 value of 9.7, as assigned by literature convention (Cy: cyclohexyl). A continuous scale of pKCD2Cl2 values covering the range from 9.7 to -3 was created and correlated with the ΔH values reported by Angelici and co-workers and literature pKa values. The pKCD2Cl2 values for 15 other hydride or dihydrogen complexes of the iron group elements and of diethyl ether were also placed on this scale. The crystal structures of [Fe(CO) 3H(PCy2Ph)2][BF4] and [Fe(CO) 3(PCy2Ph)2] revealed that the frans-oriented, bulky, unsymmetrical phosphane ligands distort the equatorial plane of the complexes. The acidity of iron carbonyl hydrides is an important feature of the reactions of iron hydrogenase enzymes.
Li, Tianshu,Lough, Alan J.,Morris, Robert H.
p. 3796 - 3803
(2008/02/08)

Conotoxin analogues and methods for synthesis of intramolecular dicarba bridge-containing peptides
According to the present invention, there is provided a range of new conotoxin derivatives and methods for synthesizing these analogues and other intramolecular dicarba bridge-containing peptides, including dicarba-disulfide bridge-containing peptides.
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Page/Page column 64; 17

(2010/11/28)

PEG-SUBSTITUTED PYRIDINE LIGANDS AND RELATED WATER-SOLUBLE CATALYSTS
Amphiphilic Group VIII metathesis catalysts, as can be used in a range of polymerization reactions and other chemical methodologies.
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(2008/06/13)

Radical phosphination of organic halides and alkyl imidazole-1- carbothioates
Taking advantage of a radical-based methodology, mild and chemoselective phosphination reactions of organic halide and alkyl imidazole-1-carbothioates have been developed. The mild reaction conditions allow labile functional groups to survive during the reaction. Copyright
Sato, Akinori,Yorimitsu, Hideki,Oshima, Koichiro
p. 4240 - 4241
(2007/10/03)

A novel mild deprotection method for phosphine-boranes
Treatment of phosphine-boranes with molecular sieves 4A in a mixture of an ethereal solvent and an alcohol provided deprotected free phosphines in quantitative yields. The phosphines can be obtained by a simple filtration/crystallization procedure in most cases. It should be noted that the current method is successfully applied to the deprotection of a phosphite-borane for the first time.
Schroeder, Marc,Nozaki, Kyoko,Hiyama, Tamejiro
p. 1931 - 1932
(2007/10/03)

Ring-closing metathesis of 2,2-diallyl derivatives of pyrrolidine and piperidine: a route to azaspiroheterocyclic structures
Transformations of 1-benzyl-2,2-di(2-propenyl)pyrrolidine and 1-benzyl-2,2-di(2-propenyl)piperidine into the corresponding 1-azaspiro[4.n]alkenes via ring-closing metathesis using accessible homogeneous catalytic systems WCl6-H2SiPh2, WOCl4-H2SiPh2, and R
Bespalova, N. B.,Shuvalova, O. V.,Zaikin, V. G.,Borisov, R. S.,Pastukhov, F. V.,Bubnov, Yu. N.
p. 645 - 648
(2007/10/03)

Phosphine and phosphido indium hydride complexes and their use in inorganic synthesis
Reaction of PR3, R = cyclohexyl (Cy), cyclopentyl (Cyp) or phenyl, with [lnH3(NMe3)] affords the 1:1 indium trihydride complexes, [InH3(PR3)]. The stabilities and spectroscopic properties of these complexes are described in terms of the phosphine ligands' steric bulk and nucleophilicity. Reaction of two equivalents of PCy3 with [InH3(NMe3)] yields the complex [InH3(PCy3)2] which has been characterised by X-ray crystallography. The first phosphido-indium hydride complex, [{InH2(PCy2)}3], has been prepared by a novel synthetic route which involves treatment of [InH3(NMe3)] with LiPCy2, Its crystal structure shows it to exist as a cyclic trimer in the solid state. The complex, [InH3(PCy3)] has been used to prepare a range of monomeric indium chalcogenolato complexes, [In(EPh)3(PCy3)], E = S, Se or Te, all of which have been structurally characterised. ' The Royal Society of Chemistry 2000.
Cole, Marcus L.,Hibbs, David E.,Jones, Cameron,Smithies, Neil A.
p. 545 - 550
(2007/10/03)

An acidity scale for phosphorus-containing compounds including metal hydrides and dihydrogen complexes in THF: Toward the unification of acidity scales
More than 70 equilibrium constants K between acids and bases, mainly phosphine derivatives, have been measured in tetrahydrofuran (THF) at 20 °C by 1H and/or 31P NMR. The acids were chosen or newly synthesized in order to cover the wide pK(α)(THF) range of 5-41 versus the anchor compound [HPCy3]BPh4 at 9.7. These pK(α)(THF) values are approximations to absolute, free ion pK(a)(THF) and are obtained by crudely correcting the observed K for 1:1 ion-pairing effects by use of the Fuoss equation. The acid/base compounds include 14 phosphonium/phosphine couples, 17 cationic hydride/neutral hydride couples, 9 neutral polyhydride/anionic hydride couples, 14 dihydrogen/hydride couples, and 4 other nitrogen- and phosphorus-based acids. The effects on pK(α) of the counterions BAr'4- and BF4- vs BPh4- and [K(2,2,2-crypt)]+ versus [K(18-crown-6)+ are found to be minor after correcting for differences in inter-ion distances in the ion-pairs involved. Correlations with v(M-H) noted here for the first time suggest that destabilization of M-H bonding in the conjugate base hydride is an important contributor to hydride acidity. It appears that Re-H bonding in the anions [ReH6(PR3)2- is greatly weakened by small increases in the basicity of PR3, resulting in a large increase in the pK(α) of the conjugate acid ReH7(PR3)2. Correlations with other scales allow an estimate of the pK(α)(THF) values of more than 1000 inorganic and organic acids, 20 carbonyl hydride complexes, 46 cationic hydrides complexes, and dihydrogen gas. Therefore, many new acid-base reactions can be predicted and known reactions explained. THF, with its low dielectric constant, disfavors the ionization of neutral acids HA over HB+ and therefore separate lines are found for pK(α)(THF)(HA) and pK(α)(THF)(HB+) when plotted against pK(a)(DMSO) or pK(a)(MeCN). The crystal structure of [Re(H)2(PMe3)5]BPh4 is reported.
Abdur-Rashid, Kamaluddin,Fong, Tina P.,Greaves, Bronwyn,Gusev, Dmitry G.,Hinman, Justin G.,Landau, Shaun E.,Lough, Alan J.,Morris, Robert H.
p. 9155 - 9171
(2007/10/03)

Synthesis of ruthenium or osmium metathesis catalysts
The present invention relates to the synthesis of highly active ruthenium and osmium vinyl alkylidene catalysts. In one embodiment, the invention may be summarized by the following reaction scheme STR1 wherein n is 1 or 2; X and X1 are each anionic ligands; L and L1 are each neutral electron donors and R17 which is hydrogen, aryl or C1 -C18 alkyl; and, R12 and R13 are each hydrogen or one of the following substituent groups: C1 -C18 alkyl, C2 -C18 alkenyl, C2 -C18 alkynyl, aryl, C1 -C18 carboxylate, C1 -C18 alkoxy, C2 -C18 alkenyloxy, C2 -C18 alkynyloxy, aryloxy, C2 -C18 alkoxycarbonyl, C1 -C18 alkylthio, C1 -C18 alkylsulfonyl and C1 -C18 alkylsulfinyl. In addition to the ease of synthesis (typically a one-step synthesis), the reactions generally may be run at or above room temperature and the resulting products usually may be used without extensive post synthesis purification.
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(2008/06/13)

Method for manufacturing acryloxypropysilane
A method to manufacture acryloxypropylsilane to a high degree of purity is achieved by hydrosilation of (A) allyl acrylate or allyl methacrylate by (B) a hydrosilane compound, using (C) a platinum-containing compound as the catalyst and (D) an organic phosphorus compound as the promoter. The acryloxypropylsilane product is expressed by General Formula I where R1 represents a hydrogen or methyl group, R2 represents a hydrolyzable group, R3 represents an aryl, alkenyl or aryl group of carbon number 1-12, and n is 0, 1, 2, or 3.
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(2008/06/13)

Process for the hydrogenation of aryl phosphines and products obtained therefrom
A process for making a cycloalkyl phosphine comprising hydrogenating an aryl phosphine in the presence of an effective amount of an aryloxide of a metal selected from the group consisting of niobium and tantalum is disclosed. Cycloalkyl phosphine products of this process, useful as ligands in a complex of a transition metal which acts as a catalyst in the formation of stereoisomers, are also set forth. Furthermore, niobium or tantalum organometallic compounds, generated in this process, useful in the catalytic hydrogenation of aryl phosphines and arene-containing polymers, is also described.
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(2008/06/13)

Regio- and Stereo-selectivity in the Hydrogenation of Aryl Phosphines by Niobium Aryloxide Compounds
The sequential hydrogenation of the three aryl rings in PPh3 by the catalyst system /3BunLi occurs with relative rates of 39:28:1; NMR analysis of the PhPCy2 obtained from and shows a predominantly all cis hydrogenation of both aryl rings has occurred.
Potyen, Mark C.,Rothwell, Ian P.
p. 849 - 852
(2007/10/02)

Catalytic Hydrogenation of Aryl Phosphines by Niobium Aryloxide Compounds: High Yield and Efficient Synthesis of Cyclohexyl Phosphine Ligands
The tris(4-methylbenzyl) compound Nb(OC6H3Ph2-2,6)2(CH2H4-4Me)3 1 (OC6H3Ph2-2,6 = 2,6-diphenylphenoxide) acts as a catalyst precursor for the hydrogenation of a variety of aryl phosphine ligands.
Yu, Joyce S.,Rothwell, Ian P.
p. 632 - 633
(2007/10/02)

Hydrogenolysis process
A process of hydrogenolysis utilizing a new catalyst consisting of a palladium phosphine complex, the phosphien having a pKa greater than or equal to 6, a chlorinated aromatic compound and hydrogen.
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(2008/06/13)

Synthesis, Characterization, and Thermolytic Behaviour of η3-Allyl(methyl)(tertiary phosphine)palladium(II), and X-Ray Structure of the Cluster 2(μ-Cl)2(μ-dppm)2>*4C4H8O (dppm = Ph2PCH2PPh2)
Complexes of the type 3-allyl)Me(L)> 3, PPh3, PPh2Me, PPhMe2, or PBun3> have been synthesized and characterized by 1H, 13C n.m.r. and mass spectroscopy.The 3-C3H5)Me(L)> complexes thermally decompose with preferential evolution of ethane rather than but-1-ene, the allylic alkylation product.The participation of the binuclear methyl-bridged intermediate 3-allyl)2(μ-Me)2> (3) is supposed.Indirect support for this is given by the thermolysis of a toluene solution of (3).The effects of phosphines, alkenes, and other additives on the thermolysis products are discussed.The structure of a complex isolated from the 3-allyl)2(μ-Cl)2>-LiMe-Ph2PCH2PPh2 (dppm) reaction system in tetrahydrofuran was revealed by X-ray analysis as two μ-chloro-μ-allyl-dipalladium(I) units bridged by two dppm ligands.
Hayashi, Yoshihito,Matsumoto, Keiji,Nakamura, Yukio,Isobe, Kiyoshi
p. 1519 - 1526
(2007/10/02)

Preparation and Properties of, and Reactions with, Metal-Containing Heterocycles, LIX. - Synthesis and Properties of η2-Thiophosphinito Complexes of Cobalt
The η2-thiophosphinito complexes (OC)2(R2R21P)Co(η2-PR23S) (3a, b, d, e, i, j, k, m, n) are obtained by reaction of ICo(CO)2(PR3)2 (1, 2) with the secondary phosphane sulfides R23HP=S in the presence of Et(iPr)2N.The Me2PS and Et2PS compounds 3a, b, d oligomerize easily to form 2R21P)Co(μ-PR23S)>n (4a, b, d) (n > 2).Upon exchange of PR21R2 (R1 = R2 = Ph) in 3a, d, j, m by PPh2Me, PPhMe2, and PMe3 in addition to the η2-thiophosphinito complexes 3f, g, l the dimeric species 2R21P)Co(μ-PR23S)>2 (5c, f, g, h, o) are formed.The dimerization tendency depends on the steric demand of the substituents R1, R2, and R3.The substituents R1 and R2 in 5f, g are responsible for energetically preferred rotamers, which are indicated in the 31P-NMR spectra.The barrier of rotation is calculated to give ΔG(excit.) = 42 kJ/mol.According to X-ray structural analysis (OC)2(Cy3P)Co(η2-PEt2S) (3e), S)>2 (5c), and S)>2 (5f) crystallize in the space group P21/c, P andP21/c with Z = 4, 2, and 2, respectively.
Lindner, Ekkehard,Frick, Klaus Erich,Fawzi, Riad,Hiller, Wolfgang,Staengle, Michael
p. 1075 - 1084
(2007/10/02)

Chemistry of metal hydrides- 25. Reactions of trans-[PtH2(P-c-Hx3)2] with carbon monoxide and other π acids
The complex trans reacts with carbon monoxide at low temperature to yield the reductive elimination of being reversible at 298 K.
Andorson, Gordor K.,Citric, Howard C.,Davies, Julian A.
p. 550 - 553
(2008/10/08)

Preparation and Characterization of Trichlorostannylplatinum Hydride Complexes Containing Sterically Bulky Phosphine Ligands
Trichlorostannylplatinum(II) hydride complexes containing sterically bulky phosphine ligands, trans-(R3P)2PtH(SnCl3)(1) R3P=t-BuPh2P, Cy3P, t-Bu2MeP) have been prepared by the reaction of hydrated tin(II) dichloride with respective chloro-platinum hydride complexes.A trans-geometry has been assigned for the complexes (1) on the basis of 1H and 31P NMR spectral studies.An unusually large magnitude of two-bond tin-hydrogen coupling (JSn-H ca.1598-1682 Hz) has been observed in the PMR spectra of these complexes.From the reaction of tin (II) dichloride with trans-(t-Bu3P)2PtH(Cl), surprisingly, a complex corresponding to (t-Bu3P)PtCl(SnCl3) (3) has been obtained.In solutions, one of the tri-t-butylphosphines of 3, undergoes intramolecular metalation generating a new, probably a platinum (IV) complex, .
Goel, Anil B.,Goel, Sarla
p. 980 - 982
(2007/10/02)

Selective formation of ethanol from methanol, hydrogen and carbon monoxide
A process for the selective formation of ethanol which comprises contacting methanol, hydrogen and carbon monoxide with a catalyst system comprising cobalt acetylacetonate, a tertiary organo Group V A compound of the periodic Table, a first promoter comprising an iodine compound and a second promoter comprising a ruthenium compound.
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(2008/06/13)

Structural studies of derivatives of methinyltricobalt enneacarbonyls. I. The crystal structure of CH3CCo3(CO)8P(C6H5) 3
The crystal and molecular structure of CH3CCo3(CO)8P(C6H5) 3 has been determined by three-dimensional X-ray analysis. Crystals of the compound are monoclinic, space group C2h5-P21/c, with four molecules in a cell of dimensions a = 12.19 (2), b = 16.11 (2), c = 17.19 (4) ?; β = 120.0 (1)°. X-Ray data were collected by conventional film techniques using Co Kα radiation, the intensities of 2189 independent reflections being measured photometrically. The structure has been refined isotropically by modified full-matrix least-squares techniques to a conventional R factor of 0.099. The monomeric molecular structure closely resembles the parent compound CH3CCo3(CO)9 being based on a Co3 triangle. The P(C6H5)3 unit has simply replaced one of the equatorial carbonyl groups, causing small distortions in the remainder of the molecule. Co-Co bond lengths are in the range 2.490-2.510 (6) ?.
Brice,Penfold,Robinson, Ward T.,Taylor, Susan R.
p. 362 - 367
(2008/10/08)