Electron-Transfer Properties of C₆₀ and <i>tert</i>-Butyl-C₆₀ Radical

Abstract

The rate constants of electron transfer from C 60 • - and C 60 2 - to electron acceptors such as allyl halides and manganese(III) dodecaphenylporphyrin are correlated with those from semiquinone radical anions and their derivatives; linear correlations are obtained between the logarithms of the rate constants and the oxidation potentials of C 60 • -, C 60 2 -, and semiquinone radical anions for different electron acceptors. Such correlations indicate that reorganization energies for the electron-transfer reactions of C 60 • - and C 60 2 - are essentially the same as those of semiquinone radical anions. The self-exchange rate constants between p -benzoquinone and the semiquinone radical anion as well as between tetramethyl- p -benzoquinone and the semiquinone radical anion in benzonitrile are determined at various temperatures by analyzing line width variations of the ESR spectra. The fast-exchange rate constants and small activation enthalpies demonstrate the efficient electron-transfer properties of the p -benzoquinone/semiquinone radical anion, C 60 /C 60 • -, and C 60 • - /C 60 2 - systems. The self-exchange rate constant between t -BuC 60 • and t -BuC 60 - is also determined by analyzing line width variations of the ESR spectra.