Theoretical Study on Structures and Stabilities of N7CR (R=H, CH3, NH2, F, Cl) Series

The existence of high energetic density material depends more on their kinetic stability. The synthesis reactions of CN7– by experimentally known N3CN and N3– were studied. The barrier of CN7– towards dissociation was theoretically calculated as 31.6 kcal⋅mol−1. The data, calculated at the CCSD(T)//B3LYP/6‐311+G(3df,2p) theoretical level, rised to 38.9 kcal⋅mol−1 when CN7H was formed by adding hydrogen anion to CN7–, indicating significant improvement in stability. The potential energy surfaces of N7CR(R= CH3, NH2, F, and Cl) system were also investigated, and the lowest kinetic barrier is 36.3 kcal⋅mol−1, 35.7 kcal⋅mol−1, 23.5 kcal⋅mol−1, and 28.5 kcal⋅mol−1, respectively. Moreover, the energy gap (Eg) of azidotetrazolates (N7CR) system was calculated by frontier molecular orbital theory to verify the stability. There are four isomers(A,B,C,D) in N7CH system, corresponding to the four modification site on the tetrazole ring. A will gradually change to B, this change only need to cross the barrier height of 4.4 kcal⋅mol−1. The transition from B to A is more easier, which resulting in A being the main form of existence. Similar to TS–A–B–1, C is the main form of existence. The decomposition transition states of the four isomers were founded and the lowest decomposition barrier of the isomers was 38.9 kcal⋅mol−1, which proved the ideal kinetic stability.