A Highly Efficient Molecular Iron(II) Photocatalyst for Concurrent CO2 Reduction and Organic Synthesis

Abstract

Molecular catalysts used for photocatalytic reduction of CO₂ heavily rely on photosensitizers to harvest light and then achieve photoinduced electron transfer to the catalytic center. However, a single earth-abundant molecular metal photocatalyst to independently execute CO₂ reduction remains a huge challenge. Herein, we report that a polypyridyl iron(II) molecular photocatalyst 1, FePAbipyBn, exhibits outstanding activity for CO₂ reduction in the presence of 1,3-diethyl-2-phenyl-2,3-dihydro-1H-benzo[d]imidazole (TON 3558 for CO production and selectivity >99%). More strikingly, molecular photocatalyst 1 takes advantage of unique photoredox properties to concurrently facilitate 2e^–/2H⁺ enamine oxidation and CO₂ reduction, resulting in value-added products of indoles and CO. This is an inaugural instance of a photoredox reaction for CO₂ reduction and organic synthesis using a molecular photocatalyst.