LAUSR

Abstract Two polypyridine complexes containing μ-OH, μ-O2 dicobalt(III) cores, [(TPA)CoIII(μ-OH)(μ-O2) CoIII(TPA)](ClO4)3 and [(BPMEN)CoIII(μ-OH)(μ-O2)CoIII(BPMEN)](ClO4)3 (TPA = tris(2-pyridylmethyl)amine, BPMEN = N,N′-dimethyl-N,N′-bis(pyridin-2-ylmethyl)ethane-1,2-diamine), have previously been reported as inactive in the light-driven water oxidation reaction (ACS Catal., 2016, 6, 5062−5068). Herein, another dicobalt(III) compound, μ-OH, μ-O2-[{(enN4)2Co2}](ClO4)3 (enN4 = 1,6-bis(2-pyridyl-2,5-diazaocta-2,6-diene), with a similar core structure was synthesized, characterized, and applied to the light-driven water oxidation reaction. Collective experiments showed that the complex itself was also inactive in the light-driven water oxidation, and that the activity observed originated from Co(II) impurities. This research establishes that complexes possessing a μ-OH, μ-O2 dicobalt(III) core structure are not appropriate choices for true molecular catalysts of water oxidation.