KINETICS OF THE RECOMBINATION REACTIONS OF CCLF WITH CF2 AND WITH CCLF

Abstract The laser flash photolysis–absorption technique has been used to study the CClF+CF 2 +M→C 2 ClF 3 +M and CClF+CClF+M→C 2 Cl 2 F 2 +M recombination reactions at 297 K. Both reactions were found to be essentially at the second-order regime from 10 Torr of the CClF and CF 2 radicals precursor C 2 ClF 3 , up to 750 Torr of mixtures of C 2 ClF 3 /He. The derived limiting high-pressure rate coefficients are (9±2)×10 −13 and (1.2±0.2)×10 −12 cm 3 molecule −1 s −1 , respectively. An analysis in terms of the ab initio density functional theory and the statistical adiabatic channel model (SACM) indicates that the formation of chlorine atoms by unimolecular decomposition of the initially formed C 2 ClF 3 or C 2 Cl 2 F 2 energized adducts can be discarded at room temperature. Employing isodesmic reaction schemes at the B3LYP/6-311++G(d,p) level of theory, the enthalpy of formation of C 2 Cl 2 F 2 , C 2 ClF 2 and C 2 F 3 are calculated to be −78.3±4, −18.1±4 and −59.9±4 kcal mol −1 , respectively.