Theoretical exploration of polynitrogen compounds N₆, N₈, N₁₀, and N₆ ions based on N₃⁻ and cyclo-N₅⁻

Nonbonding Electron Delocalization Stabilizes the Flexible N8 Molecular Assembly

“…The calculated densities of these crystals exceed 1.60 g/cm 3 , with crystal 1 exhibiting the highest density at an impressive 1.91 g/cm 3 . It is noteworthy that this density surpasses all previously estimated values based on free N 8 molecules, which typically fall within the range from 1.67 to 1.72 g/cm 3 . , Comparatively, conventional HEDMs have comparable material densities (1.70–2.02 g/cm 3 ) but significantly lower nitrogen density ρ N , ranging from 0.32 to 0.77 g/cm 3 . , The detonation parameters were calculated directly from their crystal structures by using the HASEM software, accounting for crystal spatial packing and intermolecular interaction energies, as presented in Table . Of particular note is the exceptionally high nitrogen density of crystal 1 , which bestows upon its outstanding detonation performance, with D = 9.59 km/s, p C‑J = 43.12 GPa, Q max = 1544.16 kcal/kg, and T E = 6127.55 K. These results outperform all currently utilized HEDMs, suggesting that crystal 1 is a promising candidate for high-energy-density applications.…”

“…It is noteworthy that this density surpasses all previously estimated values based on free N 8 molecules, which typically fall within the range from 1.67 to 1.72 g/cm 3 . 50,51 Comparatively, conventional HEDMs have comparable material densities Table 1. Calculated Detonation Velocity (D, in km/s), Detonation Pressure (p C-J , in GPa), Heat of Explosion (Q max , in kcal/ kg), Explosion Temperature (T E , in K), Explosive Capacity (C E , in L/kg), Impact Sensitivity (h 50% , in cm), and Nitrogen Density (ρ N , in g/cm 3 ) of the Designed All-Nitrogen Crystals, along with Data of Other HEDMs (1.70−2.02 g/cm 3 ) but significantly lower nitrogen density ρ N , ranging from 0.32 to 0.77 g/cm 3 .…”

Fluorine‐Containing Functional Group‐Based Energetic Materials

“…Among energetic materials, traditional explosives, such as 2-methyl-1,3,5trinitrobenzene (TNT), 2,4,6-triamine-1,3,5-trinitrobenzene (TATB), 1,3,5-trinitroperhydro-1,3,5-triazine (RDX), 1,3,5,7tetranitro-1,3,5,7-tetrazoctane (HMX), 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105), 2,2-dinitroethene-1,1-diamine (FOX-7) and 1,2-bis-(2,4,6-trinitrophenyl)-ethylene (HNS) have been used in industrial, mining, and military applications. [8][9][10][11][12][13] The molecular composition of these explosives includes CHNO only (Figure 1). In recent theoretical and experimental research, scientists investigated a large number of new HEDMs by combining various backbones and explosophoric groups.…”

Enhancing Stability in Polynitrogen Compounds: Mechanisms and Strategies

“…At present, the explosive energy of traditional CHNO explosive is only two times TNT equivalent, which is close to the theoretical limit and difficult to significantly improve. , Compared to traditional energetic materials, polynitrogen compounds have advantages with high density, high enthalpy of formation, ultrahigh energy, and clean and pollution-free detonation products. Therefore, they have the hope to apply as a new generation of ultrahigh energy energetic materials. − A polynitrogen compound represented by a pentazolate anion was successfully synthesized in 2017, and pentazolate salts can stably exist at room temperature. − In contrast to the pentazolate anion, the study of other polynitrogen compounds has remained in theoretical studies and experimental synthesis under extreme conditions such as ultrahigh temperature and ultrahigh pressure. − Only an azide anion and a pentazolate anion were synthesized and stabilized under general reaction conditions, while the synthesis of neutral polynitrogen compounds has not yet been resolved. , The main reason is that feasible synthetic routes for neutral polynitrogen compounds are extremely challenging. The risk of forming transition metal azides and pentazolate salts is too high, particularly.…”

“…11−13 Only an azide anion and a pentazolate anion were synthesized and stabilized under general reaction conditions, while the synthesis of neutral polynitrogen compounds has not yet been resolved. 14,15 The main reason is that feasible synthetic routes for neutral polynitrogen compounds are extremely challenging. The risk of forming transition metal azides and pentazolate salts is too high, particularly.…”