ELECTROREDUCTION OF C-60 IN APROTIC-SOLVENTS .3. VOLTAMMETRIC STUDY, AT MICROELECTRODE, OF C-60(N-) (N=0 TO 4) SOLVATION IN THE ABSENCE OF SUPPORTING ELECTROLYTE

Solvent effects on the electroreductions of C-60((x-1)-/n-)(n = 1 to 4 ) were studied in eleven single aprotic solvents and in different pyri dine-acetonitrile binary solvent mixtures. For that purpose, voltammet ric reversible half-wave potentials, E(1/2), of the electroreduction s teps were determined at a 10 mu m diam Pt disk microelectrode in the a bsence of supporting electrolyte. In this way, concomitant ion-pairing effects, operative in the presence of supporting electrolyte, were el iminated. The E(1/2) values were corrected for the ohmic drop of poten tials and correlated with solvent polarity parameters in order to acco unt for the stabilizing solvent role. The observed differences of E(1/ 2) values in different solvents were discussed in terms of weak ion-di pole interactions. The voltammetric studies of specific solvation in p yridine-acetonitrile mixtures in the absence of supporting electrolyte have shown no changes of acetonitrile solvation and the loss of at le ast two pyridine molecules from the solvation shell of C-60(n-)(n = 0 and 1) accompanying each of the first two C-60(n-1)-/n- electroreducti ons.