Theoretical Study on Structure and Properties of Tetranitropyrrole and Its Derivatives

In order to search new high-energy density materials, 2,3,4,5-tetranitropyrrole (TNP) and its methyl-, amino-, nitro-substituted derivatives were designed. Their structures were optimized at the DFT-B3LYP/6-31G* level. Heats of formation, detonation properties were calculated at the DFT-B3LYP/6-311++G** level. Nature Bond Orbital (NBO) analysis was carried to understanding the strength of trigger bond and further to access the thermal stability of the model compounds. The calculated results are as follows: the density, detonation velocity and detonation pressure of 1-methyl-2,3,4,5-tetranitropyrrloe are 1.88 g·cm-3, 8.66 km·s-1 and 34.10 GPa, respectively, which is comparable to the detonation properties of 1,3,5-trinitro-1,3,5-triaza-cyclohexane (RDX). The densities of 2,3,4,5-tetranitropyrrole and 1-amino-2,3,4,5-tetranitropyrrole are 1.93 g·cm-3 and 2.04 g·cm-3, respectively; the detonation velocities are both 9.01 km·s-1, and detonation pressures are 37.54 GPa and 38.73 GPa, which suggests that the detonation properties of TNP and ATNP are both comparable to that of 1,3,5,7-tetranitro-1,3,5,7-tetraza-cyclooctcme (HMX). With containing five nitro groups, the BDE of nitro group N(5)-NO2 is 60.8 kJ·mol-1, suggesting that pentanitropyrrole has the poorest thermal stability in all five model compounds. The calculated results and previous experimental work agree reasonably well one another, showing values in this paper are reasonable. © 2017, Editorial Board of Chinese Journal of Energetic Materials. All right reserved.