Reduced State of Iridium PCP Pincer Complexes in Electrochemical CO2 Hydrogenation

We present a computational study on the mechanism for electrochemical reduction of CO2 using a PCP pincer iridium(III) dihydride complex. Our results point toward a mechanism that involves an in situ-generated iridium(I) hydride as the active species for the CO2 to formate reduction. The iridium(III) path can operate in parallel but is associated with higher activation free energies in the reaction between the metal hydride and CO2, compared to the reaction at the in situ-generated iridium(I) species.