Cooperative B-H and Si-H Bond Activations by κ-,-Chelated Ruthenium Borate Complexes.

Cooperative E-H (E = B, Si) bond activations employing κ--chelated ruthenium borate species, [PPh{κ--(NSCH)}Ru{κ--HB(NCHS)}], () are established. Treatment of with BH·SMe yielded the six-membered ruthenaheterocycle [PPh{κ--(BHNSCH)}Ru{κ--HB(CHNS)}] () formed by a hemilabile ring opening of a Ru-N bond and capturing of a BH unit coordinated in an "end-on" fashion. On the other hand, the bulky borane HBMes shows different reactivity with that led to the formation of the two dihydroborate complexes [{κ--(NBHMes)(SCH)}Ru{κ--HB(CHNS)}] () and [PPh{κ--(NBHMes)(SCH)}Ru(κ--CHNS)] (), in which HBMes has been inserted into the Ru-N bond of the initial κ--chelated ligand. In an attempt to directly activate hydrosilanes by , reactions were carried out with HSiPh that yielded two isomeric five-membered ruthenium silyl complexes, namely [PPh{κ--(NSiPh)(SCH)}Ru{κ--HB(CHNS)}] (,), and the hydridotrisilyl complex [Ru(H){κ-(SiPhNCHS}] (). These complexes were generated by Si-H bond activation with the release of H and the formation of N-Si and Ru-Si bonds. When the reaction of was carried out in the presence of PhSiH the reaction only produced the analogous complexes [PPh{κ--(NSiPhH)(SCH)}Ru{κ--HB(CHNS)}] (,). Density functional theory (DFT) calculations have been used to probe the bonding modes of boranes/silane with the ruthenium center.