Synthesis, Structure, and Theoretical Study of Lower Trifluoromethyl Derivatives of [60]Fullerene

Abstract

A number of C60(CF3)n compounds with n = 2–10 have been synthesized by the reaction of C60 with silver trifluoroacetate and successfully isolated by means of HPLC. This resulted in the first crystal structure determination of six lower trifluoromethyl derivatives with n = 2 (single isomer), 4 (two isomers), and 6 (three isomers). A kinetic model of sequential trifluoromethylation based on the Bell–Evans–Polanyi principle has been used to explain the experimentally observed isomeric distribution in the mixtures of C60(CF3)n compounds up ton = 6. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

ESR‐Vis/NIR Spectroelectrochemical Study of C70(CF3)2−. and C70(C2F5)2−. Radical Anions

“…A numbering scheme (top, centre) is shown for clarity. 8 . [9] ) Our DFT calculations, discussed in more detail below, show that these four conformations are nearly isoenergetic.…”

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

“…Recently, number of studies on chro matographic isolation of individual compounds from such mixtures have been reported. Their structures were sug gested by NMR spectroscopy and quantum chemical calculations (C 70 (CF 3 ) 2 (one isomer), 1 C 70 (CF 3 ) 4 (one isomer), 1 C 70 (CF 3 ) 6 (two isomers), 2 C 70 (CF 3 ) 10 (four isomers), 2 and C 70 (CF 3 ) 12 (two isomers) 2 ) and/or by X ray crystallography (C 70 (CF 3 ) 6 (one isomer), 3 C 70 (CF 3 ) 8 (two isomers), 4,5 C 70 (CF 3 ) 10 (one isomer), 6 C 70 (CF 3 ) 12 (two isomers), 7-9 C 70 (CF 3 ) 14 (five isomers), 10,11 C 70 (CF 3 ) 16 (one isomer), 12 C 70 (CF 3 ) 18 (one isomer) 12 ).…”

New isomers of trifluoromethylated fullerene: C60(CF3)12 and C60(CF3)14

“…How ever, the most reliable and often the only possible method for the determination of molecular structure of isomers with a large number of CF 3 groups is single crystal X ray analysis. By now, this method has provided definitive structural information for the following C 60 (CF 3 ) n com pounds (the number of different isomers is given in brack ets): C 60 (CF 3 ) 2 (1), 3,4 C 60 (CF 3 ) 4 (2), 3,4 C 60 (CF 3 ) 6 (4), 3,4,9 C 60 (CF 3 ) 8 (2), 10-12 C 60 (CF 3 ) 10 (5), 5,13 C 60 (CF 3 ) 12 (4), 6,14,15 C 60 (CF 3 ) 14 (2), 14 C 60 (CF 3 ) 16 (3), 7 and C 60 (CF 3 ) 18 (1). 7 A mechanism of the formation of compounds C 60 (CF 3 ) n with a number of the groups attached n from two to six is considered in detail in Ref.…”

“…7 A mechanism of the formation of compounds C 60 (CF 3 ) n with a number of the groups attached n from two to six is considered in detail in Ref. 4, where the schemes of transformations of molecules with lesser num ber of CF 3 groups into the molecules with larger number of these groups have been suggested on the basis of the kinetic model and quantum chemical calculations. For the triflu oromethyl derivatives C 60 (CF 3 ) n (n = 10-18), the mech anism of the formation is not yet clear due to a large num ber of possible reaction pathways.…”

“…Initial fractional sublimation of the product under the dynamic vacuum somewhat simplifies the isomeric composition of the sublimate due to re moval of impurities. 4 Further separation of the mixture is carried out by HPLC. In this manner, in addition to the isomer C 60 (CF 3 ) 12 I mentioned above, compounds C 60 (CF 3 ) n with two to eighteen trifluoromethyl groups attached have been successfully isolated.…”