Stability, detonation properties and pyrolysis mechanisms of polynitrotriprismanes C₆H_6−n(NO₂)_n (n=1−6)

Abstract

To further test whether polynitriprismanes are capable of being potential high energy density materials (HEDMs), extensive theoretical calculations were carried out to investigate on a series of polynitrotriprismanes (PNNPs): C₆H_6−n(NO₂)_n (n=1−6). Heats of formation (HOFs), strain energies (SE), and disproportionation energy (DE) were obtained using B3LYP/6-311+G(2df, 2p)//B3LYP/6-31G* method by designing different isodesmic reactions, respectively. Detonation properties of PNNPs were obtained by the well-known KAMLET-JACOBS equations, using the predicted densities (ρ) obtained by Monte Carlo method and HOFs. It is found that they increase as the number of nitro groups n varies from 1 to 6, and PNNPs with n≥4 have excellent detonation properties. The relative stability and the pyrolysis mechanism of PNNPs were evaluated by the calculated bond dissociation energy (BDE). The comparison of BDE suggests that rupturing the C-C bond is the trigger for thermolysis of PNNPs. The computed BDE for cleavage of C-C bond (88.5 kJ/mol) further demonstrates that only the hexa-nitrotriprismane can be considered to be the target of HEDMs.

Keywords

high energy density materials / polynitrotriprismanes / heats of formation / strain energies / disproportionation energy / bond dissociation energy