Theoretical investigations on mechanisms and kinetics of the CHCFClO· with ClO· reaction in the atmosphere.

The singlet and triplet potential energy surfaces of the ClO• radical reaction with the CHCFClO• radical have been investigated at the CCSD(T)/cc-pVTZ level based on the optimized geometries at the B3LYP/6-311++G(d,p) level. On the singlet potential energy surfaces (PES), the possible reaction involves association-dissociation, direct H-abstraction and Nucleophilic Substitution 2 (S2) mechanisms. On the triplet PES, S2 displacement and direct H-abstraction reaction pathways have been investigated, which are less competitive compared with the reaction pathways on the singlet PES. The rate constants have been calculated at 10 to 10 atm and 200-3,000 K by Rice-Ramsperger-Kassel-Marcus (RRKM) theory for the important product pathways. At 200-800 K, IM1 produced (CHCFClOOOCl) by collisonal deactivation is dominant; at high temperatures, the production P1 (CHCFO + ClOOCl) becomes dominate. The calculated rate constants for CHCFClO• + ClO• are good agreement with the available experimental value. The atmospheric lifetime of CHCFClO• in ClO• is around 3.27 h. TD-DFT computations imply that IM1 (CHCFClOOOCl), IM2 (CHCFClOOClO) and IM3 (CHCFClOClO) will photolyze under the sunlight.