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

The (η3-α-silabenzyl)­molybdenum complex Cp*Mo­(CO)2{η3(Si,C,C)-Si­(p-Tol)3} (1; Cp* = η5-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{η2(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.