Enthalpy of Formation and C−F Bond Enthalpy of Fluorofullerene C60F36

The standard molar enthalpy of combustion of fluorofullerene C 60 F 36 was determined by rotating-bomb calorimetry, Δ c H ° m = −24692 ± 199 kJ·mol -1 . Using this result and the standard molar enthalpy of sublimation, Δ sub H ° m = 139 ± 8 kJ·mol -1, the values of the standard molar enthalpies of formation of C 60 F 36 in the crystalline and gaseous states were found to be −5362 ± 201 kJ·mol -1 and −5223 ± 201 kJ·mol -1, respectively. The enthalpy of reaction C 60 F 36 (g) = C 60 (g) + 36F(g) was calculated, Δ r H ° m (298.15 K) = (10617 ± 202) kJ·mol -1, or 294.9 ± 5.6 kJ·mol -1 per one C−F bond. The comparison with the enthalpy of reaction C 60 F 48 = C 60 (g) + 48F(g), Δ r H ° m (298.15 K) = 287.5 ± 3.5 kJ·mol -1 per C−F bond leads to a preliminary conclusion that C−F bond enthalpy decreases with amount of F atoms attached to the fullerene cage.