Spectroelectrochemistry of (?-oxo)bis[(phthalocyaninato)iron(III)]

The electrochemical behavior of (?-oxo)bis[(phthalocyaninato)iron(III)], [(Pc)Fe]2O, was studied in neat pyridine at a Pt-button electrode. Two single-electron-oxidation and two single-electron-reduction processes were observed for the dimer within the accessible potential range of the solvent. Variable-potential sweep rate cyclic voltammetric experiments verified the chemical reversibility of the oxidation process and the chemical irreversibility of the first reduction process at short times. Spectroelectrochemistry confirmed the long-term stability of the oxidation product and the short-lived nature of the reduction product, which decomposes ultimately to the iron phthalocyanine monomer. An electron-transfer pathway based upon the combined voltammetric, spectroelectrochemical, and coulometric results is proposed and compared to that observed for the analogous porphyrin complex (?-oxo)bis[(tetraphenylporphinato)iron(III)], [(TPP)Fe]2O.