Hydrosilylation of olefins catalysed by trans-di-µ-hydrido-bis(tricyclohexylphosphine)bis(silyl)diplatinum complexes

Abstract

The diplatinum complexes [{Pt(SiR₃)(µ-H)[(C₆H₁₁)₃P]}₂] catalyse the addition of silanes R₃SiH (R = Me, Et, PhCH₂, Ph, OEt, or Cl) to pent-1-ene, hex-1-ene, styrene, allyl chloride, and 2-methylpropene. Reactivity of the silanes is qualitatively in the order: Me₂EtSiH ≃ Me₂PhSiH ≃ Me₂(PhCH₂) SiH ClMe₂SiH > Me₃SiH > Cl₃SiH Et₃SiH (EtO)₃SiH, except for allyl chloride for which it is Cl₃SiH > Cl₂MeSiH > Me₂PhSiH ClMe₂SiH. The hydrosilylations are frequently strongly exothermic, proceeding in high yield with a catalyst: reactant ratio of 10^–4–10^–6 : 1. Hexa-1,5-diene, octa-1,7-diene, and 4-vinylcyclohexene also react readily with silanes using the same catalyst system. Hexa-1,5-diene and octa-1,7-diene afford the bis(silicon) adducts, but with 4-vinylcyclohexene only the exocyclic double bond is hydrosilylated. Catalytic addition of silanes to bicyclo[2.2.1]heptene is also described, exo-addition products being formed in 60–85% yield. The addition of Me₃GeH to hex-1-ene and to styrene is catalysed by [{Pt(GeMe₃)(µ-H)[(C₆H₁₁)₃P]}₂].