Electrochemical generation of high-valent oxo-manganese complexes featuring an anionic N5 ligand and their role in O–O bond formation
Sachidulal Biswas, Srijan Narayan Chowdhury, Panjo Lepcha, Subhankar Sutradhar, Abhishek Das, Tapan Kanti Paine, Satadal Paul, Achintesh Narayan Biswas
Abstract
(2) forms a manganese(V)-oxo (3) species, which can be oxidized further by one electron to a formal manganese(VI)-oxo transient (4). Theoretical analyses suggest that the first oxidation event (2 to 3) takes place at the metal-based d-orbital, whereas, in the second oxidation process (3 to 4), the electron eliminates from an orbital composed of equitable contribution from the metal and the ligand, leaving a single electron in the quinoline-dominant orbital in the doublet ground spin state of the manganese(VI)-oxo species (4). This mixed metal-ligand (quinoline)-based oxidation is proposed to generate a formal Mn(VI) species (4), a non-heme analogue of the species 'compound I', formed in the catalytic cycle of cytochrome P-450. We propose that the highly electrophilic species 4 catches water during cyclic voltammetry experiments and results in O-O bond formation leading to electrocatalytic oxidation of water to hydrogen peroxide.