Enhanced Acceptor Character in Fullerene Derivatives. Synthesis and Electrochemical Properties of Fulleropyrrolidinium Salts

A family of N-methylpyrrolidinium fullerene iodide salts, possessing one (or two) solubilizing chain- (s), has been synthesized. As evidenced by CV and steady-state voltammetry experiments, carried out in tetrahydrofuran (THF) solutions, these species show enhanced electron-accepting properties with respect to both the parent fulleropyrrolidines and C60. CV measurements performed at -60 °C and scan rates of 50 V/s, made possible by the use of ultramicroelectrodes, have allowed the observation, for the first time in fullerene derivatives, of six fullerene-centered reductions. Bulk electrolysis of these novel compounds, performed at the stage of the first reduction potential, generates a stable zwitterion, with both anion and cation located on the fullerene derivative.