Fused‐Pentagon Isomers of C 60 Fullerene Isolated as Chloro and Trifluoromethyl Derivatives

The carbon cage of buckminsterfullerene I h ‐C 60 , which obeys the Isolated‐Pentagon Rule (IPR), can be transformed to non‐IPR cages in the course of high‐temperature chlorination of C 60 or C 60 Cl 30 with SbCl 5 . The non‐IPR chloro derivatives were isolated chromatographically (HPLC) and characterized crystallographically as 1809 C 60 Cl 16 , 1810 C 60 Cl 24 , and 1805 C 60 Cl 24 , which contain, respectively two, four, and four pairs of fused pentagons in the carbon cage. High‐temperature trifluoromethylation of the chlorination products with CF 3 I afforded a non‐IPR CF 3 derivative, 1807 C 60 (CF 3 ) 12 , which contains four pairs of fused pentagons in the carbon cage. Addition patterns of non‐IPR chloro and CF 3 derivatives were compared and discussed in terms of the formation of stabilizing local substructures on fullerene cages. A detailed scheme of the experimentally confirmed non‐IPR C 60 isomers obtained by Stone–Wales cage transformations is presented.