Redox reactions of organic C60 derivatives

Abstract

The redox reactions of organic polyadducts of fullerene R n C60 (R = But, n = 4, 8, 12; R = PhCH2, n = 12) with various oxidants (I2, AgBF4, tetracyanoethylene (TCNE), 3,6-di-tert-butyl-o-benzoquinone, 3,6-di-tert-butyl-4,5-difluoro-o-benzoquinone, C60) and the reductant (potassium) are reported. The oxidation of R n C60 proceeds under mild conditions, in contrast to the oxidation of pristine C60. The formation of radical oxidation products was confirmed by ESR spectroscopy. For But 12C60 the reaction with excess of TCNE leads to further oxidation of the But 12C60 +· radical cation. The reduction of R n C60 with potassium does not occur at room temperature. Only on heating to 60 °C the corresponding radical anions were detected. To explain the experimental results the R n C60 molecules were studied by DFT. The calculations reveal an essential decrease in the ionization energies and electron affinities on going from C60 to R n C60.