Reverse Water-Gas Shift Reaction Catalyzed by Mononuclear Ru Complexes

A series of mononuclear Ru halogen carbonyl complexes, [PPN][Ru X-3 (CO)(3)] (X = Cl, Br, and I), were found to catalyze the reverse water-gas shift reaction (RWGSR: H-2 + CO2 -> CO + H2O). The Ru species in the reaction solution were investigated in situ using a high-pressure IR spectroscopy apparatus, which showed that [RuCl3(CO)(3)](-) was the exclusive Ru species when [PPN][RuCl3(CO)(3)] was used as a catalyst. On the basis of the IR spectra of stepwise reaction experiments, a plausible reaction mechanism for the mononuclear species is proposed.