Electrocatalytic properties of a dinuclear cobalt(III) coordination compound in molecular oxygen reduction reaction

A new dinuclear cobalt(III) coordination compound, [Co2L(μ‐N3)(N3)2]·CH3OH (1), was synthesized and characterized by elemental analysis, spectroscopic methods, and single‐crystal X‐ray analysis in which H3L is a heptadentate ligand obtained by the condensation of triethylenetetramine with 5‐bromo‐2‐hydroxybenzaldehyde. X‐ray analysis revealed that two cobalt(III) ions have distorted octahedral geometry and are connected together by a phenoxy and an azide bridging ligand. The catalytic activity of compound 1 for oxygen (O2) reduction reaction was investigated. Compound 1 can efficiently catalyze the reduction of O2 by a weak electron donor, ferrocene (Fc), at the polarized water–1,2‐dichloroethane interface. It was found that compound 1 can catalyze O2 reduction to H2O2, whereas in the presence of Fc, it can catalyze the reduction of O2 to water. Syntheses, structure, and spectroscopic studies of a new dinuclear Co(III) coordination compound were performed. Electrocatalysis of oxygen reduction at the liquid–liquid interface and hydrogen peroxide generation by the coordination compound alone were achieved. Electrocatalytic reduction of oxygen to water at the liquid–liquid interface in the presence of both the coordination compound and ferrocene was performed.