Substituted Methanes. VI. Force Constants and Calculated Thermodynamic Properties for Some Trifluoromethanes

Abstract

Using previous Raman and infrared data, force constants were calculated for CF4, CF3H, and CF3Cl, by means of the Wilson FG matrix method, with a potential energy function containing all possible second-degree terms. Fundamental frequencies for CF3D were then determined by means of the force constants found for CF3H. Finally, the heat content, free energy, entropy, and heat capacity for the ideal gaseous state at 1 atmos pressure were calculated for these 4 molecules for 11 temperatures, from 100°K to 1000°K, with a rigid rotator, harmonic oscillator approximation.