Electrocatalytic Water Oxidation by a Monomeric Amidate-Ligated Fe(III)–Aqua Complex

The six-coordinate Fe<sup>III</sup>-aqua complex [Fe<sup>III</sup>(dpaq)­(H<sub>2</sub>O)]<sup>2+</sup> (<b>1</b>, dpaq is 2-[bis­(pyridine-2-ylmethyl)]­amino-<i>N</i>-quinolin-8-yl-acetamido) is an electrocatalyst for water oxidation in propylene carbonate–water mixtures. An electrochemical kinetics study has revealed that water oxidation occurs by oxidation to Fe<sup>V</sup>(O)<sup>2+</sup> followed by a reaction first order in catalyst and added water, respectively, with <i>k</i><sub>o</sub> = 0.035(4) M<sup>–1</sup> s<sup>–1</sup> by the single-site mechanism found previously for Ru and Ir water oxidation catalysts. Sustained water oxidation catalysis occurs at a high surface area electrode to give O<sub>2</sub> through at least 29 turnovers over an 15 h electrolysis period with a 45% Faradaic yield and no observable decomposition of the catalyst.