ИСТИНА

Fine tuning of an electronic structure of a fullerene cage can be performed via structural modification of the cage as well as a exahedral attachment of various groups to sp2-carbon atoms. Insertion of difluorocarbene :CF2 is prospective way for cage modification yielding homofullerenes with preserving of an conjugated p-electron system and enhanced electron affinity. Among those compounds [6,6]-opened C60(CF2) and isomers of C70(CF2) in neutral and anionic forms are the most fully studied [1–3]. In particular, it was shown, that the excess charge density in dianions C60(CF2)2– and C70(CF2)2– is localized on carbon atoms bearing bridging CF2 group [2, 3]. This made it possible to develop a strategy of regioselective synthesis of dihydride C60(CF2)H2 [3]. Difluoromethylenated fullerenes with two or more groups are virtually unstudied. The only isomer cis‑2‑C60(CF2)2, where CF2 groups are inserted into [6,6]-bonds of adjacent hexagons, is structural characterized [1]. Here we report the first results of cis-2-C60(CF2)2 hydrogenation via protonation of in situ generated fulleroid dianions. It was shown, that hydrogenation proceeds successively with formation of dihydride C60(CF2)2H2 and tetrahydride C60(CF2)2H4. The hydrogenated products were chromatographically isolated and characterized by means of MALDI mass spectrometry, UV/Vis and NMR spectroscopy. The compound structures were elucidated by spectral data and with quantum chemical calculation at the DFT level of the theory. DFT calculations of relative energies and charge distribution of anionic and hydrogenated intermediates makes it possible to suppose mechanism of hydrogenation of cis‑2‑C60(CF2)2.