Reactions of Alkenylruthenium(II) Complexes with Hydrosilane: C-Si vs C-H Bond Formation

Maruyama, Yooichiroh; Yamamura, Kunihiro; Ozawa, Fumiyuki

doi:10.1246/cl.1998.905

Cited by 8 publications

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“…In this paper we wish to report our mechanistic studies on the reactions of alkenylruthenium(II) complexes with hydrosilanes . Since 1a in Scheme is too unstable to be isolated, further study on the mechanisms of C−Si and C−H bond formation was infeasible.…”

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confidence: 99%

Mechanisms of C−Si and C−H Bond Formation on the Reactions of Alkenylruthenium(II) Complexes with Hydrosilanes

et al. 2000

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Reactions of the four alkenylruthenium(II) complexes Ru[C(R1)CH(R2)]Cl(CO)(PPh3)2 (R1 = H, R2 = Ph (1b); R1 = H, R2 = t-Bu (1c); R1 = Ph, R2 = Ph (1d); R1 = CHCH(SiMe3), R2 = SiMe2Ph (1e)) with HSiMe2Ph, which constitute the product-forming step of ruthenium-catalyzed hydrosilylation of alkynes, have been examined. Two reaction courses are operative: one provides the C−Si coupling product PhMe2SiC(R1)CH(R2) and RuHCl(CO)(PPh3)3 (path A), and the other forms the C−H coupling product HC(R1)CH(R2) and Ru(SiMe2Ph)Cl(CO)(PPh3)2 (path B). The ratio of the two courses significantly varies with substituents on the alkenyl ligands, particularly with the α-substituent (R1). Thus, 1b and 1c, without an α-substituent, react mainly by path A. In contrast, 1d and 1e, bearing an α-substituent, exclusively undergo path B. Kinetic studies using 1b and its para-substituted styryl ligand derivatives have revealed that path A proceeds by direct interaction of the five-coordinated complexes with hydrosilane, without dissociation of the PPh3 ligand. On the other hand, path B involves dissociation of PPh3 prior to the reaction of 1d or 1e with hydrosilane. Mechanisms of the C−Si and C−H bond formation are discussed with kinetic data in detail.

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Section: Introductionmentioning

confidence: 99%

Mechanisms of C−Si and C−H Bond Formation on the Reactions of Alkenylruthenium(II) Complexes with Hydrosilanes

et al. 2000

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“…While the C−Si bond formation from alkyl(silyl)platinum complexes is the most widely accepted product-forming step for platinum-catalyzed hydrosilylation of alkenes, , little is known about this elementary process. − We recently reported that cis -PtMe(SiPh 3 )L 2 complexes (L = PMePh 2 , PMe 2 Ph) readily afford MeSiPh 3 in quantitative yields in solution. , This reaction is effectively accelerated by alkynes and alkenes added to the systems, particularly by those with electron-withdrawing substituents. Kinetic studies indicated that the MeSiPh 3 formation in the presence of diphenylacetylene proceeds via the mechanism involving prior replacement of one of the phosphine ligands (L) with diphenylacetylene, followed by reductive elimination of MeSiPh 3 from the resulting [PtMe(SiPh 3 )(PhC⋮CPh)(L)] intermediate.…”

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confidence: 99%

Thermolysis Reactions ofcis-PtR(SiPh₃)(PMe₂Ph)₂in Solution

et al. 2000

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A series of trans-and cis-PtR(SiPh 3 )(PMe 2 Ph) 2 complexes have been prepared and their thermolysis reactions in solution examined. The trans isomers (R ) Me, Et) are robust, and only the methyl complex affords MeSiPh 3 as the reductive elimination product in 72-82% yields. In contrast, the cis isomers (R ) Me, Et, Pr, Bu) form the corresponding alkylsilanes in almost quantitative yields (>97%). Despite the selective formation of the reductive elimination products, the cis-alkyl-silyl complexes bearing -hydrogens undergo a rapid repetition of the -hydrogen elimination and insertion processes, as confirmed by a deuteriumlabeling experiment using cis-Pt(CH 2 CD 3 )(SiPh 3 )(PMe 2 Ph) 2 . The alkylsilane formation from the cis isomers proceeds via two reaction paths. One is the direct C-Si reductive elimination. On the other path, the cis-PtR(SiPh 3 )(PMe 2 Ph) 2 complexes are initially isomerized to the corresponding cis-PtPh(SiRPh 2 )(PMe 2 Ph) 2 complexes by the exchange of the Pt-R group with the Si-Ph group, and the resulting phenyl-silyl complexes reductively eliminate alkylsilanes. The methyl-silyl complex decomposes exclusively by the former path, while the other alkyl-silyl complexes (R ) Et, Pr, Bu) follow mainly the latter path. Preparation and thermolysis reaction of the related cis-PtEt(GePh 3 )(PMe 2 Ph) 2 are also reported.

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Oligosilanes

Beckmann¹

2007

Comprehensive Organometallic Chemistry III

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Reactions of Alkenylruthenium(II) Complexes with Hydrosilane: C-Si vs C-H Bond Formation

Cited by 8 publications

References 12 publications

Mechanisms of C−Si and C−H Bond Formation on the Reactions of Alkenylruthenium(II) Complexes with Hydrosilanes

Mechanisms of C−Si and C−H Bond Formation on the Reactions of Alkenylruthenium(II) Complexes with Hydrosilanes

Thermolysis Reactions ofcis-PtR(SiPh₃)(PMe₂Ph)₂in Solution

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Reactions of Alkenylruthenium(II) Complexes with Hydrosilane: C-Si vs C-H Bond Formation

Cited by 8 publications

References 12 publications

Mechanisms of C−Si and C−H Bond Formation on the Reactions of Alkenylruthenium(II) Complexes with Hydrosilanes

Mechanisms of C−Si and C−H Bond Formation on the Reactions of Alkenylruthenium(II) Complexes with Hydrosilanes

Thermolysis Reactions ofcis-PtR(SiPh3)(PMe2Ph)2in Solution

Oligosilanes

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Thermolysis Reactions ofcis-PtR(SiPh₃)(PMe₂Ph)₂in Solution