Unraveling the Role of the Nitrate Ion and Solvent Water on the O‐O Bond Formation Step in Fe‐TAML Catalyzed Water Oxidation

Density functional theory‐based molecular dynamics combined with an explicit solvation model were employed to elucidate the O‐O further bond formation step in Fe‐TAML catalyzed water oxidation reaction. The water nucleophilic attack (WNA) and nitrate nucleophilic attack (NNA) on the oxo group of the high‐valent [TAML+•‐Fe5+=O] species were calculated to have comparable active barriers (24 kcal/mol vs. 22 kcal/mol). This suggests nitrate ion can behave as a co‐catalyst to promote the O‐O bond formation. More importantly, a crucial role of the presence and thermal motion of solvent water in the NNA process was observed. This was quantified by an increase of the activation energy barrier by 4 kcal/mol, determined by comparing the explicit solvent DFT‐MD simulation with implicit solvent static DFT calculation.