Photoinduced C−H Activation and Catalytic Carbonylation of Benzene − New Features of a Tris(pyrazolyl)methanesulfonato (Tpms) Rhodium(I) Complex

Irradiation of [(Tpms)Rh(CO)(PMe3)] (1) in benzene or [D6]benzene affords the rhodium(III) compounds [(Tpms)Rh(H)(C6H5)(PMe3)] (2) and [(Tpms)Rh(D)(C6D5)(PMe3)] (2-d6) respectively. The kH/kD ratio for the formation of 2 and 2-d6 was found to be 1.1. The complexes 2 and 2-d6 are stable in protic solvents. When a solution of 1 in benzene is irradiated under carbon monoxide pressure, benzaldehyde is formed catalytically with turnover numbers of up to 20. The formation of 2 and [(Tpms)Rh(H)(COC6H5)(PMe3)] (4) under catalytic conditions allows the proposal of a catalytic cycle.