(η³‑α-Silabenzyl)tungsten Complexes: An Isolable Intermediate for Interconversion between a Silylene Complex and a Silyl Complex through 1,2-Aryl Migration

η3-α-Silabenzyl complexes Cp*W­(CO)2{η3(Si,C,C)-Si­(p-Tol)2R} (1a, R = Me; 1b, R = p-Tol; Cp* = η5-C5Me5, p-Tol = p-tolyl), the first silicon analogues of η3-benzyl complexes, were synthesized by abstraction of DMAP (4-(dimethylamino)­pyridine) with BPh3 either from (aryl)­(DMAP·silylene)tungsten complexes 2a,b at room temperature or from (arylsilyl)­(DMAP)­tungsten complexes 3a,b under irradiation. Complex 1 was demonstrated to be a key intermediate for the interconversion between 2 and 3 and to serve as a synthetic equivalent for both base-free silylene complexes and coordinatively unsaturated silyl complexes.