H<sub>2</sub> Production Mediated by CO<sub>2</sub> via Initial Reduction to Formate

A Ru­(NH-NHC) complex with an open coordination site on the metal center adjacent to ligand N–H moieties has been synthesized and characterized. This complex exhibits unique reactivity upon reaction with either CO<sub>2</sub> or NaHCO<sub>3</sub>, yielding a formate-bridged bimetallic complex via a spontaneous deoxygenation reaction and formal reduction at carbon. Dehydrogenation of the formate complex leads to a Ru–carbamate species following carbon–nitrogen bond formation between the CO<sub>2</sub> moiety and the NHC ligand. This reactivity opens up new pathways for CO<sub>2</sub> reduction and is relevant to H<sub>2</sub> storage.