Five Isolated Pentagon Rule Isomers of Higher Fullerene C₉₄ Captured as Chlorides and CF₃ Derivatives: C₉₄(34)Cl₁₄, C₉₄(61)Cl₂₀, C₉₄(133)Cl₂₂, C₉₄(42)(CF₃)₁₆, and C₉₄(43)(CF₃)₁₈

Abstract

High-temperature chlorination and trifluoromethylation of C94 isomeric mixtures followed by single-crystal X-ray diffraction with the use of synchrotron radiation resulted in the structure determination of C94(34)Cl14, C94(61)Cl20, C94(133)Cl22, C94(42)(CF3)16, and C94(43)(CF3)18. Their addition patterns are stabilized by the formation of isolated C═C bonds and aromatic substructures. Four cage isomers of C94 (nos. 34, 42, 43, and 133) have been experimentally confirmed for the first time.

The First Experimentally Confirmed Isolated Pentagon Rule (IPR) Isomers of Higher Fullerene C98 Captured as Chlorides, C98(248)Cl22 and C98(116)Cl20

“…at high temperatures turned out to be very useful for confirmation of cage connectivity, owing to the ability of fullerene chlorides to crystallize directly from the reaction media, which is crucial because of very small available amounts of the starting fullerenes or fullerene mixtures. By using the chlorination method, many isomers of higher fullerenes have been identified for the first time, as in the cases of C 90 –C 96 and C 100 –C 104…”

Trifluoromethyl Derivatives of Elusive Fullerene C98

“…The lowest amount of fullerene or fullerene mixture, which is still sufficient for trifluoromethylation and subsequent HPLC separation can be estimated as 1–2 mg. More than 50 CF 3 derivatives of the most abundant C 60 or C 70 are structurally characterized, whereas the number of different C 84 (CF 3 ) n for each of the most abundant isomers of C 84 , C 84 (22), and C 84 (23), does not exceed ten . For still higher fullerenes, C 92 , C 94 , and C 96 the overall numbers of structurally investigated CF 3 derivatives are, respectively, eight (isomers C 92 (38) and C 92 (81)), four (isomers of C 94 numbers 34, 42, 43, and 61), and one for C 96 (176)), whereas the structure of C 96 (145)(C 2 F 5 ) 12 is also known …”

“…6bar under the experimental conditions.) Trifluoromethylation products of fraction IV contained mainly C 96 (CF 3 ) 16/18/20 ,C 98 (CF 3 ) 16/18/20 ,a nd small amountso fC 94 (CF 3 ) 16 .T rifluoromethylation of fraction Vg ave C 98 (CF 3 ) [16][17][18][19][20][21][22] plus C 96 (CF 3 ) [16][17][18][19][20] ,w hereas fraction VI afforded C 98 (CF 3 ) [16][17][18][19][20][21][22] and small amounts of C 96 (CF 3 ) 18/20 and C 100 (CF 3 ) [16][17][18][19][20] . The products were dissolved in n-hexane and subjected to HPLC separation in n-hexane by using as emi-preparative Buckyprep column (see the Supporting Information for more details).…”

“…[10] In C 98 (248)(CF 3 ) 18 ,t he attachment of aC F 3 group in THJ occurs due to the simultaneous formation of two nearly isolated benzenoid rings on af ullerene cage. Other cases of CF 3 additions in THJs were reported for C 76 (1)(CF 3 ) [14][15][16][17][18] , [11a] The structure of C 98 (248)(CF 3 ) 20 was characterized by am ore symmetrical arrangement of CF 3 groups on the C 2 -C 98 (248) carbon cage. Clearly,the compound C 98 (248)(CF 3 ) 18 is not aprecursor of C 98 (248)(CF 3 ) 20 in the course of trifluoromethylation.…”

“…For still higherf ullerenes, C 92 ,C 94 ,a nd C 96 the overall numbers of structurally investigated CF 3 derivatives are, respectively, eight (isomers C 92 (38) and C 92 (81)), [15] four (isomerso fC 94 numbers 34, 42, 43, and6 1), [14,16] and one for C 96 (176)), [17] whereas the structure of C 96 (145)(C 2 F 5 ) 12 is also known. [11b] In summary,t rifluoromethylationo ft he mixtures containing C 98 fullerenef ollowedb yH PLC separation of fullerene(CF 3 ) n compounds and X-ray diffraction studies resulted in the structure determination of four C 98 (CF 3 ) 18/20 compounds,w hich to date represent the largest fullerenesi solated as CF 3 derivatives.…”