Hydrosilylation and Silane Polymerization Catalyzed by Group 4 Amidometallocene Cations

Four cationic amidotitanocene complexes [Cp2Ti(NRR ')]-[B(C6F5)4] (Cp = eta 5-C5H5; 1a: R = R ' = p-anisyl; 1b: R = p-fluorophenyl, R ' = p-anisyl; 1c: R = p-fluorophenyl, R ' = phenyl; 1d: R = phenyl, R ' = 2-pyridyl) were synthesized. Complexes 1a-d undergo Ti-N bond homolysis under visible light irradiation. Complexes 1a-c catalyze the polymerization of phenylsilane to yield branched polysilane polymers with molecular weights (Mw) up to approximately 3000 and dispersity indexes (D) of 1.4-1.6. Previously reported Group 4 cationic amidometallocene complexes [Cp2Ti(NPh2)][B(C6F5)4] (Ia) and Cp2Zr(NPh2)][MeB-(C6F5)3] (IIa) were also tested in the hydrosilylation of carbonyl com-pounds with triethylsilane (Et3SiH). In some cases, complex Ia afforded completely reduced products (e.g., ethylbenzene from acetophenone), while IIa was generally more selective (e.g., (1-phenylethoxy)-triethylsilane from acetophenone) but also more active. Complex IIa could also convert anisole derivatives to phenoxysilanes with high efficiency (TON = 2000).