Theoretical study on reactions of cyclic-N3 with NO, NO2 and Cl2

In this article, we report our detailed mechanistic study on the reactions of cyclic-N3 with NO, NO2 at the G3B3//B3LYP/6-311+G(d) and CCSD(T)/aug-cc-pVTZ//QCISD/6-311+G(d)+ZPVE levels; the reactions of cyclic-N3 with Cl2 was studied at the G3B3//B3LYP/6-311+G(d) and CCSD(T)/aug-cc-pVTZ//QCISD/6-31+G(d)+ZPVE levels. Both of the singlet and triplet potential-energy surfaces (PESs) of cyclic-N3 + NO, cyclic-N3 + NO2 and the PES of cyclic-N3 + Cl2 have been depicted. The results indicate that on singlet PESs cyclic-N3 can undergo the barrierless addition-elimination mechanism with NO and NO2 forming the respective dominant products N2 + 1cyclic-NON and 1NNO(O) + N2. Yet the two reactions on triplet PESs are much less likely to take place under room temperature due to the high barriers. For the cyclic-N3 + Cl2 reaction, a Cl-abstraction mechanism was revealed that results in the product cyclic-N3Cl + Cl with an overall barrier as high as 14.7 kcal/mol at CCSD(T)/aug-cc-pVTZ//QCISD/6-31+G(d)+ZPVE level. So the cyclic-N3 radical could be stable against Cl2 at low temperatures in gas phase. The present results can be useful for future experimental investigation on the title reactions.