Energetic Effects of a Closed System Approach Including Explicit Proton and Electron Acceptors as Demonstrated by a Mononuclear Ruthenium Water Oxidation Catalyst.

When considering water oxidation catalysis theoretically, accounting for the transfer of protons and electrons from one catalytic intermediate to the next remains challenging: correction factors are usually employed to approximate the energetics of electron and proton transfer. Here these energetics were investigated using a closed system approach, which places the catalytic intermediate in a simulation box including proton and electron acceptors, as well as explicit solvent. As a proof of principle, the first two catalytic steps of the mononuclear ruthenium-based water oxidation catalyst [Ru(cy)(bpy)(HO)] were examined using Car-Parrinello Molecular Dynamics. This investigation shows that this approach offers added insight, not only into the free energy profile between two stable intermediates, but also into how the solvent environment impacts this dynamic evolution.