Selective oxidation of silanes into silanols with water using [MnBr(CO)5] as a precatalyst

The development of earth-abundant catalysts for the selective conversion of silanes to silanols with water as an oxidant generating valuable hydrogen as the only by-product continues to be a challenge. Here, we demonstrate that [MnBr(CO)(5)] is a highly active precatalyst for this reaction, operating under neutral conditions and avoiding the undesired formation of siloxanes. As a result, a broad substrate scope, including primary and secondary silanes, could be converted to the desired products. The turnover performances of the catalyst were also examined, yielding a maximum TOF of 4088 h(-1). New light was shed on the debated mechanism of the interaction between [MnBr(CO)(5)] and Si-H bonds based on the reaction kinetics (including KIEs of PhMe2SiD and D2O) and spectroscopic techniques (FT-IR, GC-TCD, H-1-, Si-29-, and C-13-NMR). The initial activation of [MnBr(CO)(5)] was found to result from the formation of a manganese(i) hydride species and R3SiBr, and the experimental data are most consistent with a catalytic cycle comprising a cationic tricarbonyl Mn(i) unit as the active framework.