Chlorination-Promoted Skeletal Transformations in Isolated-Pentagon Rule (IPR) Isomers of Fullerene C 86 to Non-IPR Chloro- and Trifluoromethyl Derivatives.

Fullerene C 86 contains two isomers obeying the Isolated-Pentagon Rule (IPR), C S -C 86 (16) and C 2 -C 86 (17). Both isomers undergo unprecedented skeletal transformations at high-temperature (400 °C) chlorination with SbCl 5 . One-step Stone-Wales rearrangement (SWR) in C 86 (17) results in the pentagon-fused #63614 C 86 cage found in the structure of #63614 C 86 Cl 24 . CF 3 derivatives with the same cage, two isomers of #63614 C 86 (CF 3 ) 18 and #63614 C 86 (CF 3 ) 18 O 2 , were obtained by high-temperature trifluoromethylation of the chlorination products with CF 3 I, followed by HPLC separation. The skeletal transformation of C 86 (16) proceeds via two SWRs under the formation of a #63624 C 86 cage with one fused-pentagon pair found in the structure of #63624 C 86 (CF 3 ) 18 . The addition patterns in skeletally transformed molecules are discussed in detail, disclosing the influence of the pentagon fusions, isolated C=C bonds, and benzenoid rings on the stability of the molecules with non-IPR C 86 cages. The chlorination-promoted SWRs in C 86 isomers have been observed for the first time, which contribute a lot to the understanding of skeletal transformations in fullerenes.