PRODUCTION, SPECTROSCOPY, AND ELECTRONIC-STRUCTURE OF SOLUBLE FULLERENE IONS

Taking advantage of the well-separated redox potentials of the mono-, di-, and trianions of C60 and C70, their room-temperature-stable, soluble monoanion radicals have been selectively prepared in bulk quantities by controlled-potential coulometry. Upon reduction, strong bands in the near-IR are observed for C60- but not for C70-. Absorptions at 1064, 995, and 917 nm are tentatively assigned to the allowed HOMO-LUMO t(lu)-t(lg) transition of C60-, in agreement with theoretical calculations. Vibrational (Raman) bands of excited C60- radical anions at 1507 and 652 cm-1 and/or t(lg) orbital splittings of similar magnitudes can be calculated from the electronic spectrum. For C70- the allowed HOMO-LUMO e1"-a1" transition is calculated to occur in the IR region. ESR signals with g values below the free electron value are observed for solutions of both C60- and C70-. For C60- the occurrence of facile electron self-exchange in solution is suggested.