A highly active and robust iron quinquepyridine complex for photocatalytic CO₂reduction in aqueous acetonitrile solution

The iron(II) complex bearing the 2,2′:6′,2′′:6′′,2′′′:6′′′,2′′′′-quinquepyridine (qnpy) ligand, [Fe(qnpy)(H₂O)₂]²⁺, is a highly efficient and robust catalyst for photocatalytic reduction of CO₂to CO in aqueous acetonitrile solution. A turnover number (TON) for CO of up to 14 095 with 98% selectivity can be achieved using Ru(phen)₃Cl₂(phen = 1,10-phenanthroline) as the photosensitizer and BIH (1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzo[d]imidazole) as the sacrificial reductant in a CO₂-saturated MeCN/H₂O (1 : 1, v/v) solution under visible light irradiation. This Fe complex is state-of-the-art for CO₂ visible-light-driven catalysis.