Electron-transfer properties of C-60 and tert-butyl-C-60 radical

The rate constants of electron transfer from C-60(.-) and C-60(2-) to elect ron accepters such as allyl halides and manganese(III) dodecaphenylporphyri n are correlated with those from semiquinone radical anions and their deriv atives; linear correlations are obtained between the logarithms of the rate constants and the oxidation potentials of C-60(.-), C-60(2-), and semiquin one radical anions for different electron accepters. Such correlations indi cate that reorganization energies for the electron-transfer reactions of C- 60(.-) and C-60(2-) are essentially the same as those of semiquinone radica l anions. The self-exchange rate constants between p-benzoquinone and the s emiquinone radical anion as well as between tetramethyl-p-benzoquinone and the semiquinone radical anion in benzonitrile are determined at various tem peratures by analyzing line width variations of the ESR spectra. The fast-e xchange rate constants and small activation enthalpies demonstrate the effi cient electron-transfer properties of the p-benzoquinone/semiquinone radica l anion, C-60/C-60(.-), and C-60(.-)/C-60(2-) systems. The self-exchange ra te constant between t-BuC60. and t-BuC60- is also determined by analyzing l ine width variations of the ESR spectra.