Synthesis of a Rhodium(III) Diethyl μ-Carbonato Complex in the Reaction of CO₂, H₂O, and Ethylene

The reaction of the Rh­(I) ethylene complex RhCl­(CH2CH2)2(PMe3)2 (2) with excess CO2 and H2O afforded a novel binuclear ethyl μ-carbonato complex, [(Me3P)4Rh2Cl2(C2H5)2(μ-CO3)] (3), in high yield. The structure of 3 was fully characterized by X-ray crystallography as well as by ordinary methods (NMR, IR, and elemental analysis). By using D2O in place of H2O, selective deuteration at the methyl position of the ethyl ligand was observed. Complex 3 reacted readily with CH2Cl2 to cleave the C–Cl bond.