Structural Chemistry of Pentagon-Fused C₈₂ Fullerene Derivatives ^#39173C₈₂(CF₃)_14,16,18 and ^#39173C₈₂Cl₂₈

High-temperature chlorination of the most stable Isolated-Pentagon-Rule (IPR) isomer of fullerene C82, C2-C82(3), invariably produces non-IPR #39173C82Cl28, containing one pentagon–pentagon fusion in the carbon cage. High-temperature trifluoromethylation of #39173C82Cl28 followed by HPLC separation resulted in the isolation and structure elucidation of eight #39173C82(CF3)n (n = 14, 16, 18) compounds. Structural chemistry of #39173C82(CF3)14,16,18 and #39173C82Cl28 is characterized by the variation of the addition patterns in the region of a pentagon–pentagon fusion. The regiochemistry of CF3 addition in the remaining cage region is similar to that of the known IPR C82(3)(CF3)n compounds. Theoretical calculations revealed that #39173C82(CF3)n possess lower thermodynamic stability than isomeric IPR derivatives.