Activationless Electron Self-Exchange of High-Valent Oxo and Imido Complexes of Chromium Corroles

Rate constants of electron self-exchange of high-valent oxo and imido complexes of chromium(V/IV) corrole have been determined in acetonitrile and toluene at various temperatures by electron paramagnetic resonance (EPR) line width variation of the EPR spectra. The observed activation enthalpies (ΔH_obs^‡) of electron self-exchange of chromium(V)-oxo and -imido corrole with the corresponding chromium(IV) complexes are zero in toluene, whereas the ΔH_obs^‡ values are slightly positive in acetonitrile. Such activationless electron self-exchange transfer resulted in extremely fast electron-transfer reactions of chromium(V)-oxo and -imido corrole in sharp contrast with slow electron-transfer reactions of other high-valent metal-oxo and -imido complexes.