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

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.