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

Abstract

The rate constants of electron transfer from C60•- and C602- 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 C60•-, C602-, and semiquinone radical anions for different electron acceptors. Such correlations indicate that reorganization energies for the electron-transfer reactions of C60•- and C602- 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, C60/C60•-, and C60•-/C602- systems. The self-exchange rate constant between t-BuC60• and t-BuC60- is also determined by analyzing line width variations of the ESR spectra.