Hydrogen-Bonding Secondary Coordination Sphere Effect on CO2 Reduction

Great efforts of the scientific community are focused on the development of catalysts for the reduction of carbon dioxide (CO2) to useful molecules such as carbon monoxide, formic acid, methanol, ethanol, methane, ethylene, or acetate. Various metal porphyrin complexes were synthesized and studied to develop highly active and selective catalysts. While the substituents on the porphyrin core (the primary coordination sphere) determine the reactivity of the metal, the introduction of the secondary coordination is important for the binding and activation of CO2. In this review, selected examples of iron porphyrin catalysts with a secondary coordination sphere capable of stabilizing intermediates of the CO2 reduction process by hydrogen bonding are presented.