Hydrosilylation of alkynes catalysed by trans- di-µ-hydrido-bis(tertiary phosphine)bis(silyl)diplatinum complexes

Abstract

But-1-yne, phenylacetylene, but-2-yne, and diphenylacetylene undergo hydrosilylation in 70–90% yield using diplatinum complexes [{Pt(SiR₃)(µ-H)[(C₆H₁₁)₃P]}₂][SiR₃= Si(CH₂Ph)Me₂, SiCl₃, or SiEtMe₂] as catalysts. Many of the reactions proceed exothermically after initial warming of the reactants. The stereochemistry of the products from but-1-yne, phenylacetylene, and but-2-yne has been established by ¹H n.m.r. spectroscopy. Hydrosilylation of but-1-yne and phenylacetylene affords as the major product trans-EtCHCHSiR₃[SiR₃= SiMe₂Ph, SiEt₃, SiCl₃, SiCl₂Me, SiClMe₂, and Si(OEt)₃] and trans-PhCHCHSiR₃ respectively corresponding to cis-SiH addition. Products corresponding to non-terminal addition are formed in minor amounts, and not at all for phenylacetylene and the chlorosilanes. But-2-yne gives vinylsilanes cis-McCHC(Me)(SiR₃), as expected for cis addition, and the same stereochemistry is inferred for the products from diphenylacetylene.