Computational comparison of Ru(bda)(py)(2) and Fe(bda)(py)(2) as water oxidation catalysts

Ru(bda)(py)(2) (bda = 2,2 '-bipyridine-6,6 '-dicarboxylate, py = pyridine) has been a significant milestone in the development of water oxidation catalysts. Inspired by Ru(bda)(py)(2) and aiming to reduce the use of noble metals, iron (Fe) was introduced to replace the Ru catalytic center in Ru(bda)(py)(2). In this study, density functional theory (DFT) calculations were performed on Fe- and Ru(bda)(py)(2) catalysts, and a more stable 6-coordinate Fe(bda)(py)(2) with one carboxylate group of bda disconnecting with Fe was found. For the first time, theoretical comparisons have been conducted on these three catalysts to compare their catalytic performances, such as reduction potentials and energy profiles of the radical coupling process. Explanations for the high potential of [Fe-III(bda)(py)(2)-H2O](+) and reactivity of [Fe-V(bda)(py)(2)-O](+) have been provided. This study can provide insights on Fe(bda)(py)(2) from a computational perspective if it is utilized as a water oxidation catalyst.