A highly accurate coupled-cluster-based ab initio model chemistry has been applied to calculate the thermodynamic functions including enthalpies of formation and standard entropies for fluorinated ethane derivatives, C 2HxF6-x (x = 0-5), as well as ethane, C 2H6. The invoked composite protocol includes contributions up to quadruple excitations in coupled-cluster (CC) theory as well as corrections beyond the nonrelativistic and Born-Oppenheimer approximations. For species CH2F-CH2F, CH2F-CHF2, and CHF2-CHF2, where anti/gauche isomerism occurs due to the hindered rotation around the C-C bond, conformationally averaged enthalpies and entropies at 298.15 K are also calculated. The results obtained here are in reasonable agreement with previous experimental and theoretical findings, and for all fluorinated ethanes except CH2FCH3 and C 2F6 this study delivers the best available theoretical enthalpy and entropy estimates.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry