New C70(CF3) n isomers (n = 12, 14, 16). Realkylation and addend rearrangements

Abstract

New isomers of trifluoromethyl derivatives of [70]fullerene, C 70 (CF 3 ) 12 (one isomer), C 70 (CF 3 ) 14 (three isomers), and C 70 (CF 3 ) 16 (one isomer) were synthesized, chromatographi cally isolated, and characterized by single crystal X ray analysis. Three of the five new isomers were obtained by annealing a mixture of higher trifluoromethyl derivatives (realkylation*). Trifluoromethylation of two individual C 70 (CF 3 ) 12 isomers revealed rearrangements of CF 3 groups on the fullerene sphere along with the direct addition to the double bonds. The relative energies of the isomers were calculated using the density functional theory.

Synthesis and structures of trifluoromethyl derivatives of fullerenes C84(16) and C84(18)

“…Compound 84 ( 10 , all ten groups are placed mirror symmetrically at para positions in adja cent six membered rings, forming a continuous chain (see Thus, all the cage pentagons each have one added CF 3 group. Two almost isolated benzenoid rings stabilize the structure.…”

“…The compounds of the formulas C 84 (16)(CF 3 ) 2m (2m = 8, 10,12,14,18) and C 84 (18)(CF 3 ) 2m (2m = 10, 12) were isolated and characterized by X ray diffraction method for the first time. The basic principles of seccessive trifluoromethylation of C 84 (16) and C 84 (18) isomers in a wider range of compositions were found based on the experimental data obtained and results of quantum chemical calculations.…”

“…In this case, different types of addition patterns are represented by continuous para chains, whose lengths are determined by the presence of the THJ in para positions. The differ ences in the arrangement of THJ positions in isomeric fullerenes lead to polyadducts, differing in both the num ber of groups and the length of the para addition chain, which is exemplified by C 84 (22) 10 , and some other compounds. A tendency of a uniform distribution of groups over pentagons is observed for compounds with twelve added groups.…”

Octafluorocyclohexa derivatives of [60]fullerene: C60(C4F8) n (n = 2, 3, 4, and 6)

“…From certain fractions, crystalline sub stances were obtained by slow evaporation of the solvent. According to X ray diffraction analysis, the fractions with retention times 8.41 and 14.78 min (toluene : hexane =3 : 2, 4.6 mL min -1 ) and with retention times 8 [5,6] fullerene (C 60 (C 4 F 8 ) 6 I) and C 60 (C 4 F 8 ) 2 I. 10 Therefore, these compounds are the reaction products in both the C 60 -C 2 F 4 I 2 and C 60 -C 4 F 8 I 2 system.…”

“…The chromatographic analysis in combination with mass spectrometry (MALDI) showed that compounds C 60 (C 4 F 8 ) 5 were also present among the reaction prod ucts, but their structures are unknown yet. Since the con tent of these compounds in the reaction products was very small, we could not isolate them in sufficient amounts, hence, we could not obtain the crystals for X ray diffrac tion analysis.…”