ELECTROCHEMISTRY OF RHODIUM AND COBALT CORROLES - CHARACTERIZATION OF (OMC)RH(PPH3) AND (OMC)CO(PPH3) WHERE OMC IS THE TRIANION OF 2,3,7,8,12,13,17,18-OCTAMETHYLCORROLE

The first oxidative electrochemistry of rhodium(III) and cobalt(III) corroles is reported in tetrahydrofuran, N,N-dimethylformamide, benzonitrile, and dichloromethane containing tetrabutylammonium perchlorate as supporting electrolyte. The investigated compounds are represented as (OMC)Rh(PPh3) and (OMC)Co(PPh3) where OMC is the trianion of 2,3,7,8,12,13,17,18-octamethylcorrole. Each complex undergoes up to three oxidations and two reductions depending upon solvent. The oxidations occur at the corrole pi-ring system while the reductions occur at the rhodium or cobalt metal center. The three one-electron oxidations are electrochemically reversible by cyclic voltammetry at fast potential scan rates, but several chemical reactions occur at lower scan rates or in the presence of added triphenylphosphine. An overall oxidation reduction mechanism is proposed for each complex and comparisons are made with the well-characterized reactions of cobalt and rhodium tetraphenylporphyrins under the same experimental conditions.