Low‐coordinate cobalt(0) N ‐heterocyclic carbene complexes as catalysts for hydrosilylation of alkynes

Among the great efforts of developing cobalt-based catalysts for hydrosilylation reactions, cobalt (II) and cobalt(I) complexes are the extensively studied ones. In contrast, explorations on cobalt(0) complexes are relatively rare. Presented herein is the investigation on the catalytic performance of low-coordinate cobalt(0) N-heterocyclic carbene (NHC) complexes in the hydrosilylation reaction of alkynes, which disclosed the fine performance of [(CyIDep)Co(η2-CH2CHSiMe3)2] (CyIDep denotes for a 1,3-bis(2′,6′-diethylphenyl)imidazole-2-ylidene that bears fused cyclohexyl group on the imidazole backbone) in catalyzing the syn-addition of a series of symmetric and unsymmetric internal alkynes with H2SiPh2, producing vinylsilanes with high regio-selectivity. Mechanistic study indicates that the catalytic reaction likely proceeds on a cobalt(0)/cobalt(II) cycle and that the high selectivity is governed by the steric nature of the NHC ligand.