Synthesis of Sm−SiH3 Complexes via σ-Bond Metathesis of the Si−C Bond of Phenylsilane

Reaction of PhSiH 3 with the samarium complexes Cp* 2 SmCH(SiMe 3 ) 2 ( 1 ) and [Cp* 2 Sm(μ-H)] 2 ( 8 ) (Cp* = C 5 Me 5 ) leads to redistribution at silicon, yielding benzene, silane, Ph 2 SiH 2, Ph 3 SiH, and dehydrocoupling products. Cleavage of the Si−C bond of PhSiH 3 is accompanied by formation of the lanthanide hydrosilyl complex [Cp* 2 SmSiH 3 ] 3 ( 2 ). Complex 2 activates the S−O bond of dimethyl sulfoxide (DMSO) to form the bridged species Cp* 2 Sm(DMSO)OSiH 2 OSm(DMSO)Cp* 2 ( 3 ). The hard Lewis bases Ph 3 PO and HMPA (HMPA = (Me 2 N) 3 PO) react with 2 to produce the base adducts Cp* 2 SmSiH 3 (OPPh 3 ) ( 4 ) and Cp* 2 SmSiH 3 (HMPA) ( 5 ), respectively. Complex 5 thermally decomposes, although not cleanly, to produce Cp* 2 Sm[OP(NMe 2 ) 2 ](HMPA) ( 6 ) in low yield. Compound 4 thermally decomposes via liberation of silane to produce ( 7 ). In toluene solution, 4 acts as a source of SiH 3 - in reactions with MeI and benzophenone, producing Cp* 2 SmI(OPPh 3 ) ( 9 ) and Cp* 2 SmOCPh 2 (SiH 3 ) ( 10 ), respectively. The high reactivity of 8 toward a stable Si−C bond is discussed in terms of possible mechanisms for this σ-bond metathesis.