Catalytic Hydrosilylation of the Carbonyl Functionality via a Transient Nickel Hydride Complex

We report the syntheses and characterization of two new sterically demanding chelate ligands, denoted PNMe3 (N-(2-(diisopropylphosphino)-4-methylphenyl)-2,4,6-trimethylanilide) and PNiPr3 (N-(2-(diisopropylphosphino)-4-methylphenyl)-2,4,6-triisopropylanilide), as well as the preparation of their nickel(II) halide complexes [(PNiPr3)Ni(μ2-Br)]2 (1) and [(PNMe3)Ni(μ2-Cl)]2 (2). The combination of complex 1 with KOtBu and Et3SiH as the hydride source can promote the hydrosilylation of a variety of carbonyl compounds in excellent yield and in a catalytic manner. The reactivity for a scope of substrates and a plausible mechanism along the hydrosilylation reaction are discussed in this work.