Structural Chemistry of Pentagon-Fused C Fullerene Derivatives C(CF) and CCl.

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