Formation of branched silanes via regiospecific hydrosilylation of vinylsilanes

Abstract: Metallocene complexes of type MCH(TMS)2 (Cp′=η5-Me5C5, M=Y, Sm), Me2SiSmCH(TMS)2 (Cp″=η5-Me4C5) catalyze rapid and clean hydrosilylation of CH2 ph name="sbnd" />SiMe2R (R=Me, Ph, NMe2, O t Bu) with PhSiH3. The distribution of 1,2-addition product versus 2,1-addition product was found to be sensitive to both catalysts and substrates. Generation of 2,1-addition product can best be achieved by use of more sterically accessible catalysts as well as substrates containing tethering functional groups. A four-centered transition state is invoked to explain these effects. Display Omitted [Copyright &y& Elsevier]