ИСТИНА

Fullerenes and their derivatives are of the particular interest as compounds with rigid molecular skeleton possessing specific properties required for material science such as photovoltaics and organic electronics. It originates from the possibility of fine tuning of π-electronic system of fullerene cage via specific arrangement of addends or via insertion of heteroatoms or molecular fragments. Recently we demonstrated that the attachment of difluorocarbene to C–C double bonds of fullerene C70 yields two isomeric C70(CF2) compounds with preserving corresponding cage C–C bond (cycloproponated derivative, so-called "closed" isomer I) and with dissociation of C–C bond (homofullerene derivative, so-called "open" isomer II) [1]. The structures of the compounds were unequivocally determined by means of NMR spectroscopy and X-Ray single crystal data. The key feature of C70(CF2) isomer I is electron-driven interconversion between the "closed" and "opened" configurations which was experimentally proved by in situ ESR spectroelectrochemical studies (Fig. 1). It makes us to suppose applicability of such type fullerene derivatives as a core for a new type of molecular switches. Here we reports the results of difluoromethylation of Cs-symmetrical octa(trifluoromethyl)fullerene, C70(CF3)8. High selictivity of the fullerene cage difluoromethylenation is predetermined by orientiring effect of CF3 groups with near-eqatorial addition pattern. The structural features of the prepared difluoromethylated derivatives of Cs-C70(CF3)8 determined by means of NMR spectroscopy and single crystal X-ray diffraction analysis will be discussed. The few unexpected effects of the attachment of CF2 moiety to fullerene cage on its electronic properties are interpreted by means of quantum chemical calculation performed at the DFT level of the theory.