σ Metathesis as a Critical Step for the Transition Metal Catalyzed Formation of Formic Acid from CO2 and H2? An Ab Initio Investigation

The hydrogenation of CO2 to formic acid catalyzed by three‐coordinate d8 hydridorhodium complexes has been studied by ab initio calculations on [HRh(PH3)2] as the model catalyst. A catalytic cycle involving a 2σ + 2σ metathesis reaction between H2 and [Rh(PH3)2(O2CH)], in which rhodium remains in the oxidation state I, is proposed as an alternative to the traditional pathway involving RhI/RhIII oxidation/reduction sequences.