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

Reaction of PhSiH3 with the samarium complexes Cp*2SmCH(SiMe3)2 (1) and [Cp*2Sm(μ-H)]2 (8) (Cp* = C5Me5) leads to redistribution at silicon, yielding benzene, silane, Ph2SiH2, Ph3SiH, and dehydrocoupling products. Cleavage of the Si−C bond of PhSiH3 is accompanied by formation of the lanthanide hydrosilyl complex [Cp*2SmSiH3]3 (2). Complex 2 activates the S−O bond of dimethyl sulfoxide (DMSO) to form the bridged species Cp*2Sm(DMSO)OSiH2OSm(DMSO)Cp*2 (3). The hard Lewis bases Ph3PO and HMPA (HMPA = (Me2N)3PO) react with 2 to produce the base adducts Cp*2SmSiH3(OPPh3) (4) and Cp*2SmSiH3(HMPA) (5), respectively. Complex 5 thermally decomposes, although not cleanly, to produce Cp*2Sm[OP(NMe2)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 SiH3- in reactions with MeI and benzophenone, producing Cp*2SmI(OPPh3) (9) and Cp*2SmOCPh2(SiH3) (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.