Performance of Gaussian-3 and Gaussian-4 level theoretical methods in estimating gas phase enthalpies of formation for representative C1 and C2 chlorofluorocarbons and hydrochlorofluorocarbons

The Gaussian-3 (G3) and Gaussian-4 (G4) ab initio post-Hartree-Fock composite methods were employed to estimate the gas phase standard state (298.15 K, 1 atm) enthalpies of formation (Delta H-f((g))degrees) for 38 representative C-1 (n = 15) and C-2(n = 23) chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs). Using the atomization approach, good agreement was found between experimental (Delta H-f((g))degrees) and corresponding G3 and G4 estimates. Where significant differences between G3/G4 and experimental Delta H-f((g))degrees exist, the errors may be due to problems with the experimental data rather than deficiencies in the theoretical methods. (C) 2010 Elsevier B.V. All rights reserved.