Hydrosilation of alkynes by an osmium cluster complex. Isolation and structural characterization of an intermediate

Article abstract of DOI:10.1021/om00037a001

Reactions of the complex Os₃(CO)₁₀(NCMe)-[Si(OMe)₃](μ-H) (1a) with the alkynes HC₂R (R = Bu^t, p-tolyl) yield complexes that upon treatment with CO at 68°C produce the silylolefins trans-R(H)C=C(H)Si(OMe)₃ (R = Bu^t, p-tolyl). One of the complexes, Os₃(CO)₁₀-[Si(OR)₃][μ-C(H)C(H)Bu ^t] (2a; R = Me) was characterized crystallographically and found to contain a bridging η²-tert-butylvinyl ligand and a terminally coordinated trimethoxysilyl group positioned cis to the bridging carbon atom of the tert-butylvinyl group. The characterization of this intermediate demonstrates that the mechanism of hydrosilation by this cluster complex is initiated by a hydride insertion mechanism.