Multiple Si–H Bond Activations in a Bis(diethylphosphino)methane-Bridged Complex of Rhodium and Iridium: Synthesis of an Unusual Bis(silyl)/μ-Silylene Complex

Abstract

The reaction of 1 equiv of a primary silane (PhSiH3 or MesSiH3; Mes = mesityl) with the bis(diethylphosphino)methane-bridged complex [RhIr(CO)3(depm)2] (1; depm = Et2PCH2PEt2) yields the silylene-bridged dihydride complexes [RhIr(H)2(CO)2(μ-SiHR)(depm)2] (2, R = Ph; 3, R = Mes) by double Si–H bond activation. Complex 2 reacts further with excess phenylsilane to yield a bis(silylene)-bridged product, [RhIr(CO)2(μ-SiHPh)2(depm)2] (4), while complex 3 reacts with CO to produce a silylene- and carbonyl-bridged product, [RhIr(CO)2(μ-CO)(μ-SiHMes)(depm)2] (5). The reaction of 1 with 1 equiv of diphenylsilane leads to a silylene-bridged dihydride, [RhIr(H)2(CO)2(μ-SiPh2)(depm)2] (6), while reaction with 2 equiv of diphenylsilane at 60 °C in the presence of CO yields the silyl/μ-silylene complex [RhIr(H)(SiPh2H)(CO)3(κ1-depm)(μ-SiPh2)(depm)] (7). The reactions of 1, 6, and 7 with excess silane at 80 °C under a CO purge yield a novel bis(silyl)/μ-silylene complex, [RhIr(SiPh2H)2(CO)4(μ-SiPh2)(depm)] (8), with accompanying loss of a depm ligand.