Electrocatalytic oxidation of organic substrates with molecular oxygen using tetradentate ruthenium(III)-Schiff base complexes as catalysts

Three complexes Ru(III)ClLn involving different tetradentate Schiff base ligands Ln (see L1, L2 and L3 in Chart 1) were used as catalysts in the oxidation of cyclooctene and tetraline in the presence of molecular dioxygen associated with benzoic anhydride. The efficiency of this oxidation reaction was tested in the presence of two apical bases: 1- or 2-methylimidazole. All complexes exhibit a quasi-reversible redox system. The electrolysis experiments were carried out at controlled potential for each complex, using different substrates such as cyclooctene and tetraline. The oxidized products are cyclooctene oxide (turnover 6.7), a mixture of 1-tetralol and 1-tetralone (turnover 7.6) respectively.