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

Abstract

The carbon cage of buckminsterfullerene I_h-C₆₀, obeying the Isolated-Pentagon Rule (IPR), can be transformed to the non-IPR C_2v-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 ¹⁸⁰⁹C₆₀Cl_n 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.