A series of polynitro-substituted 5,6-dihydrodiimidazo1,2-a:2′,1′-cpyrazine energetic compounds were synthesized by cyclization and nitration of biimidazole. All newly synthesized compounds were ...fully characterized by infrared spectroscopy, 1H and 13C nuclear magnetic resonance spectroscopy, and elemental analysis. Single-crystal X-ray diffraction, iso-chemical shielding surfaces, localized orbital locator-π, Hirshfeld surface analysis, and noncovalent interactions were employed to investigate the structures of 1–6. It is worth mentioning that compounds 3–6 are all thermally stable, with onset decomposition temperatures of 200–330 °C (DSC). Moreover, impact and friction sensitivity test results show that they are insensitive. Energy-related parameters, including densities, heats of formation, and detonation properties, were predicted according to the classical methods. In addition, the influence of the number and position of substituted nitro groups on density, heat of formation, and detonation performance was theoretically established. The superior detonation performances and good stabilities make compounds 4 and 5 useful as replacements for TNT.
Nonmetallic pentazolate (cyclo-N5 –) salts are novel polynitrogen high-energy-density materials with great potential and application prospects. Hydrogen bond networks play a vital role in improving ...the thermal stability of these compounds. In order to further increase the decomposition temperature (T d) and attain a more thorough exploration of these compounds, we evaluated and visualized the energy of hydrogen bonds (E_HBs) and the effects of HBs on T d, aromaticity, and the Mayer bond order (MBO). The increase in the total E_HBs can increase the T d, such as with 3,6,7-triamino-7H-1,2,4triazolo4,3-b1,2,4triazol-2-ium and biguanidinium pentazolates. Moreover, an increase in the maximum E_HBs can reduce the aromaticity of the cyclo-N5 – anion and increase the difference between the maximum and minimum MBO, like 3,9-diamino-6,7-dihydro-5H-bis(1,2,4triazolo)4,3-e:3′,4′-g1,2,4,5tetrazepine-2,10- diium and O-(carboxymethyl)hydroxylammonium pentazolates. In addition, increasing the number of donors of hydrogen bonds, especially the proportion of O–H bonds, can significantly increase the T d of pentazolate salts.
Polynitrogen energetic materials have become an important branch of high-energy-density materials. In this work, a theoretical exploration of structures and thermal stability in polynitrogen ...compounds N6, N8, and N10 was conducted based on synthesized azide and pentazolate compounds. By employing wave function analyses and kinetic simulations, the equilibrium geometries, properties of bonds, and indices to represent aromaticity were explored and represented. In addition, their crystal structures were predicted, and the decomposition processes and products of ab initio molecular dynamics (AIMD) simulations and transition-state calculations were carried out. Moreover, their decomposition barrier can be significantly increased by forming complexes with HMX and CL-20. Compounds HMX–1, HMX–4, CL-20–1, and CL-20–4 showed satisfactory thermal stability compared with pentazolate salts. These research results provide theoretical support and possibilities for the synthesis of polynitrogen compounds.
•Comprehensive wavefunction analyses and detonation performance predictions.•Pentazolate compounds with high density, heat of formation and detonation property.•The feasible synthesis routes and ...reaction mechanisms were proposed.
In this study, various polynitrogen pentazolate derivatives: aminopentazole, diaminopentazole cations, azopentazole (N12), and 1,2-diazopentazole (N14), were designed and computed. Based on quantum chemistry calculations and wavefunction analyses, the equilibrium geometry, bond orders, atoms-in-molecules (AIM) analysis, atomic charges, electrostatic potential distribution, frontier molecular orbitals, and many indices to represent aromaticity were determined and represented. In addition, their densities, heats of formation, detonation properties, and impact sensitivities were calculated using thermodynamics methods. These polynitrogen pentazolate derivatives could exhibit high density (1.668–1.965 g·cm−3); high heat of formation (2.96–15.86 kJ·g−1); outstanding detonation performance (D: 9070–12,243 m·s−1, P: 34.8–70.0 GPa); in particular, N14 (D: 12,243 m·s−1, P: 70.0 GPa); acceptable thermostability and sensitivity (h50: 12–49 cm). The excellent energetic performance demonstrates that polynitrogen pentazolate derivatives are promising energetic materials. The synthesis of aminopentazole and diaminopentazole cations may be achieved via an amination agent and the synthesis of N12 and N14 using an oxidizing agent.
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Exploring heat-resistant explosives that are easy to synthesize is a major challenge in the research of energetic materials. In this study, two novel fused-ring energetic compounds, namely ...3,6-dinitropyrazolo1,5-
a
pyrimidine-5,7-diamine (
4
) and 5-amino-3,6-dinitropyrazolo1,5-
a
pyrimidin-7(4
H
)-one (
5
), were successfully prepared
via
a simple synthetic method. In addition, their structure, thermal stability, mechanical sensitivity and detonation performance were fully explored. Noteworthily, compounds
4
and
5
both exhibit excellent thermal stability (
T
D
(4) = 325 °C and
T
D
(5) = 291 °C), particularly compound
4
, which features an "amino-nitro-amino" arrangement similar to that of TATB and exhibits a high density of 1.88 g cm
−3
and a greater thermal decomposition temperature than hexanitrostilbene (HNS, 316 °C). In addition, due to the aza-fused structure,
4
and
5
possess higher positive heats of formation (332.9 kJ mol
−1
and 181.4 kJ mol
−1
) than LLM-105 (11.0 kJ mol
−1
). These advanced features endow
4
and
5
with superior detonation performance (
V
d
(4) = 8338 m s
−1
and
P
(4) = 30.7 GPa;
V
d
(5) = 8097 m s
−1
and
P
(5) = 29.8 GPa) than TATB (
V
d
= 8179 m s
−1
and
P
= 30.5 GPa) and HNS (
V
d
= 7170 m s
−1
and
P
= 21.8 GPa). This study enriches prospects for the molecular design and crystal engineering of novel energetic materials with admirable molecular stability.
Introducing the structural characteristics of TATB into the fused structure is a promising strategy for preparing high-energy heat-resistant explosives.
Multicyclic compounds containing a 1,2,5-oxadiazole core exhibit high density and excellent thermal stability due to their 3,4-substitution arrangement, which facilitates attaining a planar ...conformation. In this work, a series of new compounds (2–5) that consist of 1,2,5-oxadiazoles bonded to other heterocycles or modifiable groups via stable C–C bonds are synthesized through condensation reactions of 3-amino-4-cyanofurazan. Then their 14 energetic derivatives were developed. The synthesis methods and chemistry involved in the production of these novel energetic materials have been explained. The new compounds were investigated through IR, NMR ( 1 H and 13 C) spectroscopy, elemental analysis, and single-crystal X-ray diffraction studies. The thermal decomposition temperatures of the samples were determined using thermogravimetry and differential scanning calorimetry and found to range from 136 °C to 345 °C (onset). Furthermore, the results of impact and friction testing showed that these compounds exhibited greater insensitivity compared to FOX-12. Detonation properties, densities, and heats of formation were determined through the EXPLO5 v6.05.04 program, a gas pycnometer, and the Born–Haber energy cycle, respectively. The combination of good detonation properties, enhanced thermal stabilities, and low sensitivities indicates that certain compounds (8, 9, 12, 14, and 16) could be promising contenders for insensitive energetic uses. Interestingly 6-(1 H -tetrazol-5-yl)-1,2,5oxadiazolo3,4- b pyridine-5,7-diamine (7) displays fluorescence, making it a promising option for usage as an energetic filler or in the production of energetic materials to facilitate easy detection.
A series of hexaaminocobalt(III) based energetic compounds Co(NH3)6(N3)3 (1), Co(NH3)6(N5)2(N3) (2), Co(NH3)6(N5)3 (3), and their chloride and nitrate complex salts 4–6 were designed and ...synthesized by simple metathesis reactions. As far as we know, compound 3 is the first trivalent metal pentazolate salt. The structures of all the new energetic compounds were confirmed by single-crystal X-ray diffraction. Their physicochemical and energetic properties, such as density, thermal stability, sensitivity, and detonation properties, were also evaluated. Due to the extensive hydrogen bonding network, the detonation properties of these salts and acceptable mechanical sensitivities (IS = 3–6 J, FS = 40–80 N) hold the prospective potential as green primary explosives. This work suggests that the cyclo-pentazolate anion has good compatibility with azide and nitrate ions, and they can act together as hydrogen bond acceptors to form novel energetic materials with controllable properties through hydrogen bonds.
Two novel potassium pentazolate frameworks KN 5 ·1.5CH 3 COOK (1) and KN 5 ·3CF 3 COOK (2) were achieved by changing the content and type of K-carboxylates. All the compounds were characterized via ...infrared (IR), single-crystal X-ray diffraction, thermogravimetric analysis, and differential scanning calorimetry. 1 exhibited two unique nanocages featuring KN 5 and CH 3 COOK. 2 with a high density (2.097 g cm −3 ) was constructed by replacing the H atoms of 1 with the most electronegative F atoms. The F atoms of 2 form channels that constituted a peculiar porous structure. The electronegativity, atomic charge, and electrostatic potential were further analyzed for the differences between the two frameworks and explained the reasons for the constitution. This work demonstrates that it is possible to regulate the crystal structure and density through appropriate additives.
Two novel potassium pentazolate frameworks KN5·1.5CH3COOK (1) and KN5·3CF3COOK (2) were achieved by changing the content and type of K-carboxylates. All the compounds were characterized via infrared ...(IR), single-crystal X-ray diffraction, thermogravimetric analysis, and differential scanning calorimetry. 1 exhibited two unique nanocages featuring KN5 and CH3COOK. 2 with a high density (2.097 g cm−3) was constructed by replacing the H atoms of 1 with the most electronegative F atoms. The F atoms of 2 form channels that constituted a peculiar porous structure. The electronegativity, atomic charge, and electrostatic potential were further analyzed for the differences between the two frameworks and explained the reasons for the constitution. This work demonstrates that it is possible to regulate the crystal structure and density through appropriate additives.
![Pyrazolo[1,5-]pyrimidine wi...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/1466-8033/small "Pyrazolo[1,5-]pyrimidine with similar \"amino-nitro-amino\" arrangement characteristics to TATB: a novel heat-resistant explosive with fused structure")
