The placement of a strongly trans-influencing ligand on a ruthenium center opposite an anchoring silyl group of the tetradentate tripodal tris(phosphino)silyl ligand, [SiP(3)(Ph)](-) ([SiP(3)(Ph)](-) = tris(2-(diphenylphosphino)phenyl)silyl), has been explored. Installation of alkyl or terminal phosphide ligands trans to the anchoring silyl group affords the complexes [SiP(3)(Ph)]RuR (R = Me (2), CH(2)Ph (4), PPh(2) (5), P'Pr(2) (6)). Complexes 2, 4, and 5 are thermally unstable. Complexes 2 and 4 decay to the cyclometalated complex [SiP(2)(Ph)P'(Ph)]Ru (3), whereas complex 5 decays to the cyclometalated phosphine adduct [SiP(2)(Ph)P'(Ph)]Ru-(PHPh(2)) (7). Complex 3 is found to effect E-H (E = H, C, Si, Ge) bond activation of substrates such as secondary silanes and germanes to yield the structurally unusual silylene complexes [SiP(3)(Ph)]Ru(H) (SiRR') (R = R' = Ph (10a), R = Ph R' = Me (10b)) and the germylene complex [SiP(3)(Ph)]Ru(H)(GeR(2)) (R = Ph) (11) via double E-H activation transformations. Both theory and experiments suggest electrophilic character at the silylene moiety. Reaction of 3 with catecholborane, in contrast to silanes and germanes, results in insertion of the B-H unit into the M-C bond of the cyclometalated species to yield the borate complex [SiP(2)(Ph)P(Ph)-B(cat)]Ru(mu-H) (14). Complex 3 also reacts with bis(catecholato) diboron to yield a similar complex, [SiP(2)(Ph)P(C6H3B(cat))-B(cat)]Ru(mu-H) (15), with selective borylation of all ortho C-H bond.
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