METATHESIS OF SILICON-CONTAINING OLEFINS .10. METATHESIS OF VINYLTRIMETHYLSILANE CATALYZED BY RUTHENIUM COMPLEXES

Self metathesis of vinyltrimethylsilane in the presence of an oxygenated benzene solution of RuCl2(PPh3), and RuH2(PPh3)4 follows an unusual course and yields two products, 1,2-bis(silyl)ethene (E) and 1,1-bis(silyl)ethene, with products of dimerization, namely 1,4-bis(silyl)butenes-2 (E + Z) and butenylsilanes as well as hexamethyldisiloxane. Gaseous ethylene and traces of ethane were also detected. It is proposed that vinylsilane is inserted into the Ru-Si bond (via ortho-metallation of the ruthenium triphenylphosphine complex) in competition with pathways involving metal-carbene species. Complexes of ruthenium containing no phenylphosphine give stereoselectively only the (E)-product of metathesis (even in the absence of oxygen and hydrosilane co-catalysts) accompanied by traces of the same by-products.