Hydrido(hydrosilylene)tungsten Complexes: Dynamic Behavior and Reactivity Toward Acetone

Reaction of a labile tungsten nitrile complex, [(Cp*)W(CO)2(NCMe)Me] (Cp*=?5-C5Me5), with H3SiC(SiMe3)3 gave the hydrido(hydrosilylene) complex [(Cp*)(CO)2(H)W?Si(H){C(SiMe3)3}] (1?a). The hydrido(silylene) complex [(?5-C5Me4Et)(CO)2(H)W?SiMes2] (2) (Mes=2,4,6-Me-C6H2) was synthesized by a similar reaction with H2SiMes2. There is a strong interligand interaction between the hydrido and silylene ligands of these complexes; this was confirmed by a neutron diffraction study of [D2]1?b, that is, the deuterido and ?5-C5Me4Et derivative of 1?a. The exchange between the W?H and the Si?D groups was observed in the deuterido complex [D]1?a. This H/D exchange proceeded slowly at room temperature, but very rapidly under UV irradiation. Variable-temperature NMR spectroscopy measurements show the dynamic behavior of carbonyl ligands in 1?a. Complex 1?a reacted with acetone at room temperature to give mainly a hydrosilylation product, [(Cp*)(CO)2(H)W?Si(OiPr){C(SiMe3)3}] (3?a), along with a siloxy complex, [(Cp*)(CO)2WO(Si(H)iPr{C(SiMe3)3})] (4?a). At low temperature, a different reaction, namely, a-H abstraction, proceeded to give an equilibrium mixture of 1?a and a dihydrido(silyl) complex, [(Cp*)(CO)2(H)2W(Si(H){OC(?CH2)Me}{C(SiMe3)3})] (5).