Chlorination‐Promoted Cage Transformation of IPR C₉₂ Discovered via Trifluoromethylation under Formation of Non‐classical C₉₂(NC)(CF₃)₂₂

Abstract

High‐temperature trifluoromethylation of isolated‐pentagon‐rule (IPR) fullerene C92 chlorination products followed by HPLC separation of C92(CF3)n derivatives resulted in the isolation and X‐ray structural characterization of IPR C92(38)(CF3)18 and non‐classical C92(NC)(CF3)22. The formation of C92(38)(CF3)18 as the highest CF3 derivative of the known isomer C92(38) can be expected. The formation of C92(NC)(CF3)22 was interpreted as chlorination‐promoted cage transformation of C92(38) followed by trifluoromethylation of non‐classical C92(NC) chloride. Noticeably, C92(NC)(CF3)22 shows the highest degree of trifluoromethylation among all known CF3 derivatives of fullerenes. The addition patterns of C92(38)(CF3)18 and C92(NC)(CF3)22 are discussed and compared to the chlorination patterns of C92(38)Cln compounds.

Trifluoromethyl Derivatives of Elusive Fullerene C98

“…In C 98 (248)(CF 3 ) 18 , the attachment of a CF 3 group in THJ occurs due to the simultaneous formation of two nearly isolated benzenoid rings on a fullerene cage. Other cases of CF 3 additions in THJs were reported for C 76 (1)(CF 3 ) 14–18 , C 94 (61)(CF 3 ) 20 , and non‐classical C 92 ( NC )(CF 3 ) 22 …”

“…It means that the difference in addend sizes between CF 3 and Cl does not play a decisive role in this case, whereas the stabilizing factors of isolated substructures are of greater importance. Therefore, it can be assumed that a hypothetic C 98 (248)(CF 3 ) 22 can possess the same addition pattern as in C 2 ‐C 98 (248)Cl 22 though the addition of 22 CF 3 groups to higher fullerene cages is up to now experimentally confirmed only in the recent case of non‐classical C 92 ( NC )(CF 3 ) 22 . Further addition of addends is feasible only in chloro derivatives, because fullerene cages easily accept Cl addends in adjacent positions as, for example, in C 2 ‐C 98 (248)Cl 26 (Figure ) or other chloro derivatives of higher fullerenes with 28–32 attached Cl atoms…”

“…11). The E rel /1CF 3 values for C 98 (248)(CF 3 ) 18 and C 98 (116)(CF 3 ) 18 (−3.9 and −4.2 kJ mol −1 , respectively) are practically the same as for C 92 (38)(CF 3 ) 18 (−3.7 kJ mol −1 ) . The E rel /1CF 3 values for C 98 (248)(CF 3 ) 20 and C 98 (120)(CF 3 ) 20 (−5.3 and −7.6 kJ mol −1 ) indicate a similar stability as for C 94 (61)(CF 3 ) 20 (−5.1 kJ mol −1 ) and somewhat higher stability than those of C 70 (CF 3 ) 20 or C 84 (22)(CF 3 ) 20 (−10.1 and −12.1 kJ mol −1 , respectively).…”

Theoretical studies on the characterization of classical and non-classical C68 isomers and their newly synthesized derivatives by spectroscopy

“…Henceforth, it is universally acknowledged that a growing abundance of heptagoncontaining fullerenes has been excellently compounded as derivatives. [12][13][14][15][16][17][18][19][20][21][22] Despite the presence of a substantial number of non-classical fullerenes, the non-classical fullerene C 1 -C 68 (NC3), where NC stands for the abbreviation of nonclassical and the value three represents the number of heptagons in the suffix, is the most distinctive since it is the initial fullerene to be completely devoid of an independent pentagon. 23 Additionally, it represents the smallest cage with three different fused pentagon types below C 80 among non-classical fullerenes.…”

Capturing nonclassical C70with double heptagons in low-pressure combustion

“…11 All the heptafullerenes are actually captured as their exohedral or endohedral derivatives according to the literature published so far. [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] Synthetic methods for heptafullerene derivatives can be divided into two categories, chemical shrinkage from existing conventional fullerenes (such as C 60 , 12 C 76 , 13 C 78 , 14 C 86 , 15,16 C 88 , 8,17 C 90 , 18 C 92 , 19,20 C 96 , 21 C 100 , [22][23][24] C 102 , 25 and C 104 26) in a top-down fashion and in situ synthesis starting from graphite and/ or chloro/hydrocarbon molecules typically in a bottom-up manner.…”