ELECTROCHEMICAL STUDIES AND ELECTRONIC SPECTROSCOPIC EXAMINATION OF SOME COBALOXIMATIC COMPLEXES BASED ON 2,3-BUTANEDIONE DIOXIME OR DIMETHYLGLYOXIME WITH IDENTICAL OR MIXED AXIAL LIGANDS

Electrochemical studies (cyclic voltammetry, voltammetry at rotating d isc electrode and coulometry) have been carried out in acetonitrile, a t a platinum electrode, for three Co(III) containing cobaloximes havin g the same in plane ligand (the butanedione dioximate or dimethylglyox imate Hdmg(-)). The complexes examined, [Co(Hdmg)(2)I(py)], H[Co(Hdmg) (2)I-2] and [Co(Hdmg)(2)(py)(2)]NO3 (where py=pyridine), are neutral, anionic and cationic, respectively. Their voltammetric traces reveal t he presence of a series of oxidation and reduction charge transfer pro cesses. The combined use of mixed axial ligand and appropriate chemica l reactions, enables the accumulation of information on the nature (co balt based, iodide based or glyoximate-centered) of the electron trans fer processes that occur during the reductive and the oxidative proces ses. Some solvolysis of the complexes is observed and discussed in ter ms of axial ligand exchange equilibria. The uv-visible spectra for the se complexes in acetonitrile show some absorptions at low energy which are attributed either to pi-pi transition, metal-to-ligand charge tr ansfer or to d-d transitions. Copyright (C) 1996 Elsevier Science Ltd.