Chemistry of Cobalt Acetate. 7. Electrochemical Oxidation of &mc;3-Oxo'Centered Cobalt(III) Acetate Trimers.

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]