H-1 NMR relaxation and theoretical calculation study on Tris (pentafluorophenyl)borane as a catalyst in preparation of Poly(carborane-siloxane) polymers

Poly(carborane-siloxane) polymers were successfully synthesized by tris(pentafluorophenyl)borane catalyzing diorganohydroxysilanes (Si-OH) and dihydrosilanes (Si-H) to form siloxane bond and release hydrogen. The structure of monomers and polymers were characterized by H-1, C-13, Si-29 NMR and FI-IR. Furthermore, in the present study, the qualitative characterization of silicon hydrogen bond in dihydrosilanes activated by catalyst B (C6F5)(3) was investigated by H-1 NMR relaxation test and theoretical calculation. The results shown that silicon hydrogen bond (Si-H) and B(C6F5)(3) form the complex [Si center dot center dot center dot H center dot center dot center dot B(C6F5)(3)] which is relevant to chemical re-activity. In addition, dihydrosilanes exhibit the following reactive activity order: 1,1,3,3-tetra-methyldisiloxane > 1,7-bis(3-hydridotetramethyldisiloxanyl)-m-carborane > diphenylsilane > methylphenylsilane > 1,7-bis(dimethylsilyl)-m-carborane. This synthetic method offers a new effective approach to synthesize poly(carborane-siloxane) polymers and the reactive activity order has a guide significance for experimental system design