Tracking an Fe (O) Intermediate for Water Oxidation in Water.

High-valent iron-oxo species are appealing for conducting O-O bond formation for water oxidation reactions. However, their high reactivity poses a great challenge to the dissection of their chemical transformations. Herein, we introduce an electron-rich and oxidation-resistant ligand, 2-[(2,2'-bipyridin)-6-yl]propan-2-ol to stabilize such fleeting intermediates. Advanced spectroscopies and electrochemical studies demonstrate a high-valent Fe (O) species formation in water. Combining kinetic and oxygen isotope labelling experiments and organic reactions indicates that the Fe (O) species is responsible for O-O bond formation via water nucleophilic attack under the real catalytic water oxidation conditions.