Dehydrocoupling reactions of hydrosilanes with group 4 metallocenes Cp2MY2 (M = Ti, Zr, Hf; Y = F, OPh, NMe2)

Abstract

Dehydrocoupling polymerization of phenylsilane with group 4 metallocene precatalysts Cp2MY2 (M = Ti, Zr, Hf; Y = F, OPh, NMe2) under comparable conditions has been examined. All nine title metallocenes produced polysilane products which ranged in molecular weight from 1100 to 4400 and exhibited ratios of linear to cyclic products from ~2 to 30. The highest molecular weight polysilanes observed for each metal were obtained from Cp2M(NMe2)2 and the highest percentage of linear polysilane was found with Cp2Hf(NMe2)2. The near stoichiometric reactions of Cp2MY2 with PhSiH3, PhMeSiH2, and Ph2MeSiH were monitored by 1H, 19F and 29Si NMR spectroscopy and in all cases exchange products containing Si-Y were identified. Metal hydride species could be observed only with Cp2TiY2.Key words: metallocene, dehydrocoupling, polymerization, hydrosilanes, polysilane.