Impact of the Ligand Flexibility and Solvent on the O–O Bond Formation Step in a Highly Active Ruthenium Water Oxidation Catalyst

[Image: see text] By advanced molecular dynamics simulations, we show that for a highly active ruthenium-based water oxidation catalyst the dangling carboxylate group of the catalyst plays an important role in the crucial O–O bond formation step. The interplay of the flexible group and solvent molecules facilitates two possible pathways: a direct pathway with a single solvent water molecule or a mediated pathway involving two solvent water molecules, which have similar activation barriers. Our results provide an example for which a realistic molecular dynamics approach, incorporating an explicit description of the solvent, is required to reveal the full complexity of an important catalytic reaction in aqueous solvent.