A Masked Cuprous Hydride as a Catalyst for Carbonyl Hydrosilylation in Aqueous Solutions.

Redox-unstable cuprous hydridotriphenylborate was isolated as an N-heterocyclic carbene adduct [(IPr)Cu(HBPh3 )] (IPr=1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) with good thermal stability. Although this compound displays a contact ion-pair structure, CuI H-like catalytic activity was envisaged in carbonyl hydrosilylation. Sufficient moisture stability allowed the catalysis in aqueous/organic media. Mechanistic study further showed that a phenyl group on the borate anion is abstracted by [(IPr)Cu]+ to give the cationic organocopper complex [(IPr)2 Cu2 (μ-Ph)][BPh4 ].