Felton, R.H., Owen, G.S., David Dolphin, and Fajer, J.
J. Am. Chem. Soc.
Cyclic voltammetry of tetraphenylporphyrin (III) iron chloride(I) or octaethylporphyrin iron(III) chloride in CH2 Cl2 showed that reversible one-electron oxidation occurs at ε½ = 1.13 V vs. SCE (aq.) and 0.99 V, respectively. One-electron, oxidative half-wave potentials of ε½ = 0.84 V and 1.09 V were observed for μ-bis-[tetraphenylporphyrin iron(III)] (II) and of ε½ = 0.66 V and 0.96 V for μ-oxo-bis[octaethylporphyrin iron(III)]. The one-electron oxidation products prepared by controlled potential electrolysis displayed optical spectra differing only slightly from the respectively parent iron(III) porphyrins. PMR spectra of the oxidized I and II in CDCl3 were observed. Optical, polarographic and PMR data ruled out π-electron oxidation of the porphyrin ring. The oxidized ferric porphyrins contain formal Fe(IV).