Chloro- And Trifluoromethyl Derivatives Of A Pentagon-Fused C-60:(C60cl24)-C-1810, (C60cl20)-C-1810, And C-1810(60)(Cf3)(14)

The carbon cage of I-h-C-60, obeying the isolated-pentagon rule (IPR), can be transformed to the non-IPR D-2h-C-1810(60) cage via two successive Stone-Wales rearrangements in the course of high-temperature chlorination of C-60 with SbCl5. Two chloro derivatives, C-2v-(C60Cl24)-C-1810 and C-2v-(C60Cl20)-C-1810, have been isolated by high-performance liquid chromatography (HPLC). High-temperature trifluoromethylation of the chlorination products with CF3I, followed by HPLC separation, afforded a non-IPR CF3 derivative, C-s-C-1810(60)(CF3)(14). Structural elucidation of the isolated compounds revealed that all eight sites of pentagon-pentagon fusions on the carbon cage are preferentially occupied by Cl atoms or CF3 groups. According to density functional theory calculations, chloro and CF3 derivatives of C-1810(60) are more stable than the isomeric derivatives of C-1809(60) or IPR C-1812(60), possessing respectively four or no sites of pentagon fusion in their carbon cages.