Regiodivergent Hydrosilylation of Alkenes at Nickel: Tuning the Selectivity by Complex Stoichiometry and Silane Identity

Herein, we show nickel silylphosphine complexes as efficient regioselective catalysts for the hydrosylilation of alkenes. Regiospecific or regioselective diphenylsilane hydrosilylation of aromatic and aliphatic alkenes to the linear isomer is catalyzed by complexes [HNi(kappa2(P,Si)-Ph2PC6H4-2-CH2SiMe2)(PPh3)2], and [HNi(kappa2(P,Si)-Ph2P-2-C6H4CH2SiiPr2)(PPh3)], while regiospecific formation of the branched hydrosilylation product is obtained upon employment of the bisligated complex [Ni(kappa2(P,Si)-Ph2PC6H4-2-CH2SiMe2)2] with phenylsilane. Turnover numbers of up to 10,000 for the linear and 200 for the branched isomers in this study, situate these base-metal catalysts amongst the best catalysts reported. Mechanistic insights support non-radical pathways involving nickel hydride intermediates.