Synthesis and electrochemical behavior of regioisomeric bismethanofullerene derivatives

A series of regioisomeric bis-methanofullerenes (diethyl[60]fullerenobisace tate) were prepared by reaction of the sulfonium ylide with C-60. Seven sta ble resultant regioisomers were completely isolated on a preparative HPLC a nd identified by FT-IR, UV-vis, TOF-MS, and H-1 and C-13 NMR measurements. The structures of these bisadducts were assigned based on 1) the relationsh ip of the polarities of the regioisomers with the elution order from HPLC; 2) a comparison of their UV-vis spectra with those of corresponding Bingel- Hirsch bisadducts; and 3) the identification of their molecular symmetries by their H-1 and C-13 NMR spectra. The electrochemical properties of the re sultant regioisomeric bismethanofullerene derivatives were investigated thr ough cyclic voltammetry (CV). The bisadducts exhibited more negative reduct ion potential than the pristine C-60. Trans-2- and cis-3-bisadducts had the least negative potential E-1/2(1) of all the other bisadducts.