Abstract
Mechanisms and reaction channels of the CHBr2 and CBr3 with NO2 reactions have been studied by quantum chemistry methods. The calculated results indicating that the title reactions can take place on either the singlet or triplet potential energy surfaces (PES) and the pathways on the triplet PES should be much less competitive than that on the singlet PES. On the singlet surface, CHBr2 radical can associate with NO2 to barrierlessly generate adduct IM1 (CHBr2NO2), followed by isomerization to IM2a (trans–cis-CHBr2ONO) and IM2b (trans–trans-CHBr2ONO), which can easily interconvert to IM2c and IM2d. Starting from IM2 (IM2a, IM2b, IM2c and IM2d), the most favorable channel involves the 1,3-Br migration along with NO bond rupture of IM2a leading to P1 (CHBrO+BrNO), or the 1,4-Br shift accompanied by the NO bond cleavage of IM2d to form P5 (CHBrO+BrON). Moreover P1 and P5 can further dissociate to generate P6 (CHBrO+NO+Br). Much less competitively, IM2a could take the 1,3-H-shift associated with the NO bond cleavage to give product P2 (CBr2O+HNO). Due to highly energy barriers and unstable products, the pathways of formation other products could be neglected. For the singlet potential energy surface of CBr3+NO2 reaction, the only dominant product is found to be P1 (CBr2O+BrNO), which can direct rupture N-Br single bond of BrNO to form the secondary product P2 (CBr2O+NO+Br). The present study may be helpful for further experimental investigation of the title reactions.
Published Version
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