The low temperature heat capacities of fluorofullerenes

A.I .Druzhinina, N.A. Galeva, R.M. Varushchenko, O.V. Boltalina, L.N. Sidorov.

J. Chem. Thermodynamic, vol. 31, (1999) (in print)

ABSTRACT. The heat capacities of the fluorinated fullerenes C60F48, C60F46, and C60F36 have been measured in an adiabatic vacuum calorimeter over the temperature range from 8 K to 356 K. The heat capacities curve of C60F48 reveals a gradual "order-disorder" transition between temperatures 315 K and 345 K. Thermodynamic properties of c60F48 in the transition region are as follows: Ttrs = (329.6 0.4) K, trsH = (7.0 0.7) kJ.mol-1 and trsS = (21 2) J.K-1.mol-1. The Cp curve C60F46 exhibits a glassy crystal transition in the temperature interval from 210 to 245 K. The temperature dependence of the heat capacitie of C60F36 does not indicate any anomaly. The molar thermodynamic functions Hom(T)- Hom(0), Som(T)- Som(0), and Gom(T)- Hom(0) over the temperature range studied and entropies of formation fTSom at T = 298.15 K have been calculated for C60F48, C60F46, and C60F36.

Laboratory of Thermochemistry