Metal-mediated activation of carbon dioxide in the gas phase: Mechanistic insight derived from a combined experimental/computational approach

In this invited review we address, from a mechanistic point of view, three fundamental reactions of carbon dioxide transformation in the gas phase: (i) its reduction to carbon monoxide via oxygen-atom transfer to a suitable oxygen acceptor, (ii) translocation of a hydride from metal hydrides to generate a formate ligand, and (iii) coupling processes with CO2 to make CC and CO bonds. Where appropriate, the findings are compared with related reactions in the condensed phase. The gas-phase studies described, in conjunction with computational work, permit to uncover numerous mechanistic aspects of elementary steps in the making and breaking of bonds, reactions which, by definition, are obscured in solution due to ill-defined effects of the environment.