Silyl and bis(silyl)hydride complexes of ruthenium: Effect of ancillary groups on the oxidative addition of Si-H bonds

Abstract

Ruthenium alkyl complexes Cp(PMe 3) 2 RuCH 2SiMe 3 ( 2) and Cp(PPh 3) 2RuMe ( 3) reacted with hydrosilanes forming ruthenium silyl and/or bis(silyl)hydride complexes. Complex 2 reacted with HSiR 3 at 100°C forming the corresponding silyl complexes Cp(PMe 3) 2RuSiR 3[SiR 3 = SiCl 3 ( 4), SiMeCl 2 ( 5), SiMe 2Cl ( 6)] in high yields. At 125–150°C, 2 reacted with HSiEt 3 giving a mixture of the silyl Cp(PMe 3) 2RuSiEt 3 ( 7) and the bis(silyl)hydride Cp(PMe 3)Ru(SiEt 3) 2H ( 8); this mixture can be converted solely to 7 upon reaction with PMe 3. Complex 3 reacted with HSiEt 3 at 100°C forming Cp(PPh 3) 2RuSiEt 3 ( 9). The reaction of 3 with neat HSiCl 3 at 100°C forms a mixture of Cp(PPh 3)Ru(SiCl 3) 2H ( 10) and Cp(PPh 3) 2RuSiCl 3 ( 11), with 10 being the major product. At lower concentrations of HSiCl 3 (< 2 M), the reaction with 3 forms mixtures of 10 and 11 but with 11 being the major product. Mixtures of 10 and 11 can be converted to 11 upon reaction with excess PPh 3. Similarly, 11 reacts with neat HSiCl 3 to generate a mixture of 10 and 11. The effects of the ancillary ligands on ruthenium and the nature of the hydrosilane on the rate and course of reaction are also discussed.