ИСТИНА

Trifluoromethylfullerenes are the structurally most abundant class of characterized polyderivatives of fullerenes [1]. The various motifs of the arrangement of CF3 form various π-conjugate systems on the fullerene core, which opens the possibility to adjust their optical and luminescent properties [2]. Traditionally, trifluoromethylfullerenes are produced in a heterogeneous reaction between CF3I and fullerene upon heating. The resulting complex mixture of derivatives requires time-consuming chromatographic purification, which limits the production of individual compounds in macroquantities. Thus, the purpose of this paper is to search and develop alternative methods of trifluoromethylation of fullerenes and their derivatives. It is known that alkali metal difluorochloroacetates are a convenient substrate for the generation of in situ difluorocarbenoids for the synthesis of difluoromethanofullerenes [3]. However, we found that the reaction of alkali metal difluorobromoacetates with fullerene C60 leads to different products depending on the nature of the alkali metal. While the reaction with Li and Na difluorobromoacetates yields the expected difluoromethanofullerenes, the selective formation of the previously unknown compound C60(CF3)H was observed in the reactions of salts K and Cs. The latter was isolated and characterized by NMR spectroscopy on 1H, 19F and 13C nuclei. The principle possibility of using a new approach for the trifluoromethylation of fullerenes and their derivatives was successfully completed in reactions with fullerene C70 and C60(CF2)n. It was shown that the reaction proceeds with the formation of previously unknown compounds C60(CF2)n(CF3)H and two isomers C70(CF3)H. Thus, a fundamentally new method of regioselective trifluoromethylation of fullerenes and their derivatives was proposed, which opens the possibility of preparative synthesis of fullerene derivatives with specified electronic properties.