Water Oxidation Catalysis by Mono- and Binuclear Iron Corroles

Considering
the overwhelming importance and involvement of iron
in numerous biocatalytic processes, the scarceness of synthetic iron
complexes as water oxidation catalysts (WOCs) is highly surprising.
Given the increasing interest in metallocorroles as electrocatalysts,
the current study addressed the water-oxidizing ability of mononuclear
and two types of binuclear iron corroles: μ-oxo bridged and
linked through β-pyrrole C atoms. This disclosed the modulation
of electronic factors for lowering the electrochemical onset potential
for water oxidation by the monomeric iron corroles and the fact that
the C–C-linked dimer outperforms both the monomer and the μ-oxo
dimer as a WOC. Parallel investigations on the corresponding bis-cobalt
dimer uncovered it to be the best catalyst not only in terms of efficacy
but also with regard to the stability of the catalytically active
species. The electrode-adsorbed iron corrole is shown to be a good
WOC, at a relatively low voltage with a very high Faradaic efficacy.