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, (CuH)-H-I-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)Cu-2(mu-Ph)][BPh4].