Silylation of styrene with vinylsilanes catalyzed by RuCl(SiR3)(CO)(PPh3)(2) and RuHCl(CO)(PPh3)(3)

The coupling reaction of styrene with vinylsilanes catalyzed by ruthenium complexes was investigated, RuHCl(CO)(PPh3)(3)(I) and RuCl(SiR3)(CO)(PPh3)(2) (where R-3 = Me-3 (II), Me2Ph (III), (EtO)(3) (IV)) were found to be efficient and selective catalysts for the formation of E-1-phenyl-2-silylethene and evolution of ethene. Stoichiometric reactions of styrene with the Ru-Si bonds of II-IV in argon and silylstyrene with the Ru-H bond in air (I-*) as well as a MS study of the product of the deuterated styrene with vinylsilanes are convincing evidence for the mechanism of the process involving the migratory insertion of styrene into the Ru-Si bond (and vinylsilane into Ru-H bond) followed by P-H (and P-Si) elimination to give phenylsilylethene (and ethene). Kinetic tests (TOF) indicate a prior dissociation of the PPh3 molecule (or by its oxygenation) from I to yield pentacoordinated RuHCl(CO)(PPh3)(2) which is almost as active as II.