Catalysis of CO2 reduction by diazapyridinophane complexes of Fe, Co, and Ni: CO2 binding triggered by combined frontier MO associations involving a SOMO

The Fe- and Co-based molecular catalysts are found to utilize multiple sets of frontier MO associations at the CO2 binding by including one of the SOMOs in a high-spin Fe(i) and Co(i) center, respectively, accelerating these oxidative addition steps.