Trifluoromethyl derivatives of pentagon-fused C60: 1809C60(CF3)n (n = 10, 12, 14, 16).

The carbon cage of buckminsterfullerene Ih-C60, obeying the Isolated-Pentagon Rule (IPR), can be transformed to the non-IPR C2v-1809C60 cage by a single Stone-Wales rearrangement (SWR) in the course of high-temperature chlorination of C60 with SbCl5. The following high-temperature trifluoromethylation of the chlorination products with CF3I afforded non-IPR CF3 derivatives, 1809C60(CF3)n. X-ray diffraction studies of 1809C60(CF3)n (n = 10, 12, 14, 16) revealed that the sites of pentagon-pentagon fusions on the carbon cage are preferentially occupied by CF3 groups. The addition patterns of 1809C60(CF3)n and related 1809C60Cln are compared, demonstrating a prevailing role of pentagon-pentagon fusions in the stability and structural chemistry of these compounds. Further SWR skeletal transformations of 1809C60 are discussed and compared with the experimental data available.