ONE-ELECTRON OXIDATION OF METALLOPORPHYCENES AS STUDIED BY RADIOLYTICMETHODS

One-electron and two-electron oxidations of 2,7,12,17-tetrapropylporph ycene (H(2)TPrPc) and its Fe, Co, Ni, Cu, and Sn complexes in CH2Cl2, CCl4, and 2-PrOH solutions have been studied by radiolytic techniques. Formation and decay of intermediates formed upon one-electron oxidati on have been followed by kinetic spectrophotometric pulse radiolysis, and the absorption spectra of stable oxidation products have been reco rded following gamma-radiolysis. H(2)TPrPc is oxidized to the pi-radic al cation and then to the dication, which is stable in aprotic solvent s but is transformed to a different product in 2-PrOH. Similar oxidati on to the pi-radical cation and then to the dication was observed for the Cu-II, Sn-IV, Co-III, and Fe-III porphycenes. Co-II and Ni-II porp hycenes underwent radiolytic oxidation to form stable C-III and Ni-III products. The stability of the latter is in contrast with previous el ectrochemical observations, and the difference is ascribed to the effe ct of the axial ligand.