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A family of mu3-oxotricobalt (III,III,III) acetate bridged complexes is irreversibly reduced and the reversibility is ascribed to the removal of an electron from a pi(super *) -orbital centered on the mu3-oxygen.

Electrochemical and spectroelectrochemical properties of five cobalt(III) acetate complexes [Co[supIII],[sub3](μ[sub3]-O)(CH[sub3]- CO[sub2])[sub5](OR)(py)[sub3]][PF[sub6]] are described, where py = pyridine and R = OCCH[sub3] (A), H (B), CH[sub3] (C), CH[sub2]CH=CH[sub2] (D), and CH[sub2]C[sub6]H[sub5] (E). Each is reduced irreversibly as observed by cyclic voltammetry at room temperature and at -40 °C in acetonitrile at scan rates up to 20 V s[sup-1], but oxidized reversibly to a mixed-valence Co(III)[sub2]Co(IV) species at ∼ 1.23 V vs the ferrocenium/ferrocene couple. Controlled potential coulometry confirmed a one-electron-oxidation process. Spectroelectrochemical oxidation of A at 5 °C showed isosbestic points in the electronic absorption spectrum that showed the oxidized complex to be stable in solution for at least 1 h. [ABSTRACT FROM AUTHOR]

Electrochemical and spectroelectrochemical properties of five cobalt(III) acetate complexes [CoIII3(mu3-O)(CH3CO2)5(OR)(py)3][PF6] are described, where py=pyridine and R=OCCH3 (A), H (B), CH3 (C), CH2CH=CH2 (D), and CH2C6H5 (E). Each is reduced irreversibly as observed by cyclic voltammetry at room temperature and at -40 degrees C in acetonitrile at scan rates up to 20 V s(-1), but oxidized reversibly to a mixed-valence Co(III)2Co(IV) species at approximately 1.23 V vs the ferrocenium/ferrocene couple. Controlled potential coulometry confirmed a one-electron-oxidation process. Spectroelectrochemical oxidation of A at 5 degrees C showed isosbestic points in the electronic absorption spectrum that showed the oxidized complex to be stable in solution for at least 1 h.