Reaction of Dinuclear Rhodium 4,5-Diazafluorenyl-9-Carboxylate Complexes with H2 and CO2

The reactivity of the dinuclear Rh­(I) 4,5-diazafluorenyl-9-carboxylate complex 4 with H2 was explored in an attempt to reduce the trapped CO2-derived moiety. After overnight reaction with H2 the only observed species at room temperature by NMR spectroscopy was the decarboxylated 4,5-diazafluorenyl (L–) Rh­(III) complex 1. A series of stepwise stoichiometric reactions with H2, NMR experiments at low temperatures, trapping experiments with added PPh3 or CO2, and 13C-labeling experiments were conducted in an attempt to identify the fates of the CO2-derived portion of 4 and the second Rh center.