Synthesis, Structure, and Reactions of a (η3-α-silabenzyl)molybdenum Complex: A Synthetic Equivalent of a Coordinatively Unsaturated Silyl Complex

The (eta(3)-alpha-silabenzyl)molybdenum complex Cp*Mo(CO)(2){eta(3)(Si,C,C)-Si(p-Tol)(3)} (1; Cp* = eta(5)-C5Me5, p-Tol = p-C6H4Me) was synthesized in high yield by removal of 4-(dimethylamino)pyridine (DMAP) from the (arylsilyl)(DMAP)molybdenum complex Cp*Mo(CO)(2)(DMAP){Si(p-Tol)(3)} (2) with BPh3. The precursor, complex 2, was readily prepared by reaction of the (DMAP)(methyl)molybdenum complex Cp*Mo(CO)(2)(DMAP)Me (3) with tri-p-tolylsilane (HSi(p-Tol)(3)) through methane elimination. Study on the reactivity of 1 toward DMAP and nitrile revealed that complex 1 serves as a synthetic equivalent of the 16-electron silyl complex Cp*Mo(CO)(2){Si(p-Tol)(3)}. Thus, complex 1 reacted with DMAP quantitatively at room temperature to reproduce arylsilyl complex 2 through dissociation of the arene carbon atoms coordinated to molybdenum. Complex 1 also reacted with acetonitrile at room temperature to give the N-silyliminoacyl complex Cp*Mo(CO)(2){eta(2)(C,N)-C(Me)=NSi(p-Tol)(3)} (4) exclusively via cleavage of the Mo-C(arene) bonds followed by insertion of nitrile into the Mo-Si bond.