E.s.r. evidence for chromium (V) porphyrinates

Abstract

The oxidation of chloro-5, 10, 15, 20-tetraphenyl-porphyrinatochromium(III) with iodosylbenzene proceeds with oxygen transter to chromium and two-electron oxidation of the metal to give a chromium (V) porphyrinate complex; the e.s.r. spectra of this complex, its ¹⁷O-derivative, and its t-butylamine adduct show strong electron hyperfine interactions with the metal nucleus and the metal ligands and indicate a metal-centred radical as expected for chromium(V).