Looking for high‐energy density compounds among hexaazaadamantane derivatives with CN, NC, and ONO₂ groups

Abstract

Density functional theory (DFT) was employed to evaluate the heats of formation (HOFs) for hexaazaadamantane (HAA) derivatives with OCN, ONC, and OONO 2 groups, respectively. This was done by designing isodesmic reactions at the B3LYP/6-31G* level of theory, where the HAA cage skeletons were kept unbroken to produce more accurate results, and all HOFs for the required reference compounds, NH 2 CN, NH 2 NC, NH 2 ONO 2 , and (CH 2 NH) 3 , were derived from the G 3 theory calculation based on the atomization energies. The calculation results show that the HOFs of HAA derivatives are mainly affected by the number and the position of substituent groups, all the obtained HOFs are positive, and the ONC derivatives have the most HOFs among the three types of derivatives with the same number of substituent groups. The detonation velocity (D) and detonation pressure (P) were obtained from the empirical Kamlet-Jacobs equations. All the ONC and OCN derivatives of HAA have lower densities (), heats of explosion (Q), D, and P. However, these properties of OONO 2 derivatives are rather high and vary with the number of OONO 2 groups. Considering the easiness for synthesis and relative stability, 2,4,6,8-hexaazaadamantanenitrate is finally recommended as a potential candidate of a high-energy density compound (HEDC).

Theoretical studies on new potential high energy density compounds (HEDCs) adamantyl nitrates from gas to solid

“…This phenomenon has also been found in other 32 ONO 2 derivatives [52] and cage cubylnitrates [35] , which have the same structure of C ONO 2 that exists ONO 2 derivatives of adamantane. However, our calculations have also predicted that the HOFs of hexaazaadamantane ONO 2 derivatives, of which the ONO 2 groups are bonded to N in a form of N ONO 2 , increase with n increasing [24] . This shows that the HOF variation of ONO 2 derivatives is related to the atom connected to ONO 2 .…”

“…Great effort has been put into the synthesis of nitro derivatives of adamantane (polynitroadamantanes, PNAs), and nowadays polynitroadamantanes with six or fewer groups have been successfully synthesized [13 22] . Theoretical studies have been carried out on the NO 2 , CN and NC derivatives of adamantane, and three PNAs with 8 10 NO 2 groups were recommended as potential HEDC [23,24] according to the usual criteria (density U > 1.9 g·cm 3 , detonation velocity D > 9.0 km·s 1 , and detonation pressure P > 40.0 GPa) [25] and the stability requirement (the trigger bond dissociation energy E > 125.40 kJ·mol 1 ) [26] .…”

Molecular design of new nitramine explosives: 1,3,5,7-tetranitro-8-(nitromethyl)-4-imidazolino[4,5-b]4-imidazolino-[4,5-e] pyridine and its N-oxide

“…Since Q and ρ are unknown for the unsynthesized hypothetical compounds, to predict their detonation properties, the modified K-J equations based on the calculation results of quantum chemistry were recommended [23,24,26,[38][39][40][41][42][43], in which the density of the explosive ρ was replaced by the crystal theoretical density (ρ c ) computed by the following equation:…”

DFT Studies on Detonation Properties, Pyrolysis Mechanism, and Stability of the Nitro and Hydroxyl Derivatives of Benzene

“…5,6,[31][32][33][34][35][36][37] To evaluate the stability of the title compounds, the bond dissociation energy (BDE) denoted by the energy difference between the radical products (A• and B•) and the reactant (A-B) was calculated using Eq. (1) as was adopted in previous works.…”