Theoretical Study On The Reaction Br And CH₂BrCl

The study and determination of rate constants for a specific .chemicalreaction has always been one of the main research fields in chemistry. It is oneof the most active subjects to predict the rate constants in different conditionstheoretically.In this research, we imitated the multiple-channel reaction Br+CH₂BrC1obtained directly from electronic structure calculations by means of the directdynamics methods and the theoretical investigations and then explored it. Theoptimized geometries, frequencies, and minimum energy path (MEP) are allobtained at the MP2/6-311+G(d,p) level, and energetic information is furtherrefined at the QCISD(T)/6-311+G(3df,2p) (single-point) level. The rateconstants for three reaction channels, H-abstraction, Br-abstraction, andCl-abstraction, are calculated by the improved canonical variation transitionstate theory (ICVT) with small-curvature tunneling (SCT) contributions over thewide temperature region 200—4000 K. The theoretical two-parameter formulaof overall rate constants is given as k=9.93×10^-19T^2.48exp(-3890.89/T) (incm³molecule(¹)s^-1).For the title reaction, H-abstraction reaction channel is the predominantlychannel in the lower temperatures while as the temperature increases, thecontributions of Br-and Cl-abstraction channels should be taken into account.