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Spectroelectrochemical investigation of the dicobalt complex 1 (M′[DOUBLE BOND] M″ [DOUBLE BOND] CoII), which was synthesized in only a few steps in good yield from simple starting materials, revealed the presence of the mixed-valence CoII–CoI complex as well as the CoI–CoI complex. The UV/VIS spectrum and the ESR results for the mixed-valence species indicate that the unpaired electron is delocalized. The electrocatalytic reduction of O2 on carbon electrodes coated with 1 occurs at −0.34 V (vs. SCE). R [DOUBLE BOND] CH2C(CH3)3.