Theoretical studies on the reactions X + CHBrF₂ (X = F, Br)

Theoretical investigations are carried out on the reactions F + CHBrF₂ → CBrF₂ + HF (R1) and Br + CHBrF₂ → CBrF₂ + HBr (R2) by means of direct dynamics method. The minimum energy path (MEP) is obtained at the BH&H-LYP/6-311G(d,p) level, and energetic information is further refined at the QCISD(T)/6-311+G(2df,2p) (single-point) level. The rate constants for both reactions are calculated by canonical variational transition state theory (CVT) with the small-curvature tunneling (SCT) correction in a wide temperature range 200-3000 K. The theoretical rate constant is in good agreement with the available experimental data. Furthermore, the rate constants of reaction Cl + CHBrF₂ → CBrF₂ + HCl (R3) calculated in the other paper are added to discuss the effects of halogen substitution on the rate constants of this class of hydrogen abstraction reactions.