Carbonyl and Oxalyl Bridged Bis(1,5‐Diaminotetrazole)‐Based Energetic Salts

High density energetic salts containing nitrogen rich cations and carbonyl‐ or oxalylbis(diamino‐tetrazole) anions, which were obtained from cyanogen azide and hydrazine, were readily synthesized. In every case, a new family of energetic salts 3 – 14 were characterized by vibrational spectroscopy, multinuclear (¹H, ¹³C, ¹⁵N) NMR, elemental analyses, density, differential scanning calorimetry and impact sensitivity. Compound 12 was structured by single crystal X‐ray diffraction. The densities of 3 ‐ 14 , determined by gas pycnometer, range between 1.500 and 1.676 g cm^?3. The heats of formation and detonation properties for these stable salts were calculated by using Gaussian 03 and Cheetah 5.0, respectively.     

Synthesis,Crystal Structure,and Properties of Energetic Copper(II) Complex based on 3,5‐Dinitrobenzoic Acid and 1,5‐Diaminotetrazole

Energetic copper(II) complexes based on 3,5‐dinitrobenzoic acid (HDNBA) and 1,5‐diaminotetrazole (DAT), Cu(DNBA)₂(H₂O)₂ ( 1 ) and Cu(DAT)₂(DNBA)₂ ( 2 ) were synthesized and characterized by elemental analysis, IR spectroscopy, single‐crystal and powder X‐ray diffraction. In both complexes, Cu^II was coordinated to a plane tetragon, by four oxygen atoms from two DNBA^– ions and two coordinated H₂O molecules for 1 , and by two oxygen atoms and two nitrogen atoms from different DNBA^– ions and DAT ligands for 2 . Differential scanning calorimetry (DSC) and thermogravimetry (TG) analyses were employed to measure the thermal decomposition processes and non‐isothermal kinetics parameters of the complexes. The thermal decomposition onset temperatures of 1 and 2 are 321 and 177 °C. The apparent activation energies of the first exothermic decomposition peaks of 1 and 2 are 247.2 and 185.2 kJ · mol^–1. Both 1 (35 J, > 360 N) and 2 (12.5 J, > 360 N) are less sensitive than RDX. The catalytic effects on the decomposition of ammonium perchlorate (AP) of 1 and 2 were studied by DSC. All results supported the potential applications of the energetic complexes as additives of solid rocket propellants.     

4‐Nitro‐3‐(5‐tetrazole)furoxan and Its Salts: Synthesis,Characterization, and Energetic Properties

A series of new energetic salts based on 4‐nitro‐3‐(5‐tetrazole)furoxan (HTNF) has been synthesized. All of the salts have been fully characterized by nuclear magnetic resonance (¹H and ¹³C), infrared (IR) spectroscopy, elemental analysis, and differential scanning calorimetry (DSC). The crystal structures of neutral HTNF ( 3 ) and its ammonium ( 4 ) and N‐carbamoylguanidinium salts ( 9 ) have been determined by single‐crystal X‐ray diffraction analysis. The densities of 3 and its nine salts were found to range from 1.63 to 1.84 g cm^?3. Impact sensitivities have been determined by hammer tests, and the results ranged from 2 J (very sensitive) to >40 J (insensitive). Theoretical performance calculations (Gaussian 03 and EXPLO 5.05) provided detonation pressures and velocities for the ionic compounds 4 – 12 in the ranges 25.5–36.2 GPa and 7934–8919 m s^?1, respectively, which make them competitive energetic materials.     

Synthesis,Characterization, and Energetic Properties of Alkaline and Alkaline Earth Salts of 5,5′‐bistetrazole‐1,1′‐diolate

5,5′‐Bistetrazole‐1,1′‐diolate‐based energetic salts from alkaline (Li⁺, K⁺, and Na⁺) and alkaline earth metal salts (Mg²⁺, Ca²⁺, and Ba²⁺) were synthesized in a simple, straightforward manner and were characterized by IR and NMR spectroscopy, and elemental analysis. Single‐crystal X‐ray diffraction of 4 salts (Li⁺, Na⁺, K⁺, and Mg²⁺) is given. The X‐ray structures show that in the title compounds, the metal atoms are bonded to the nitrogen and oxygen in the bistetrazole ring to form the sandwich structure. In addition, thermal stabilities of all title compounds were determined with differential thermal analysis‐thermal gravity analysis. All these new materials exhibit excellent thermal stabilities, high density, and excellent insensitivity to impact (h ₅₀ > 60 cm). Especially, the potassium salt is of interest as potential “green heat‐resistance explosive” with high density and high thermal stability as well as low sensitivity.     

3,4,5‐Trinitropyrazole‐Based Energetic Salts

High‐density energetic salts that are comprised of nitrogen‐rich cations and the 3,4,5‐trinitropyrazolate anion were synthesized in high yield by neutralization or metathesis reactions. The resulting salts were fully characterized by ¹H, ¹³C NMR, and IR spectroscopy; differential scanning calorimetry; and elemental analysis. Additionally, the structures of the 3,5‐diaminotriazolium and triaminoguanidinium 3,4,5‐trinitropyrazolates were confirmed by single‐crystal X‐ray diffraction. Based on the measured densities and calculated heats of formation, the detonation performances (pressure: 23.74–31.89 GPa; velocity: 7586–8543 ms^?1; Cheetah 5.0) of the 3,4,5‐trinitropyrazolate salts are comparable with 1,3,5‐triamino‐2,4,6‐trinitrobenzene (TATB; 31.15 GPa and 8114 ms^?1). Impact sensitivities were determined to be no less than 35 J by hammer tests, which places these salts in the insensitive class.     

Two Energetic Salts based on 5,5′‐Bitetrazole‐1,1′‐diolate: Syntheses,Characterization, and Properties

Two salts based on 1H,1′H‐5,5′‐bitetrazole‐1,1′‐diolate (BTO) anion with pyrazole ( 1 ) and imidazole ( 2 ) cations were synthesized with metathesis reactions. Structural characterization was accomplished for them by using the element analysis, Fourier transform infrared spectroscopy (FT‐IR), NMR and mass spectrum, and X‐ray single crystal diffraction. Thermal analysis for the title salts were determined by means of differential scanning calorimetry (DSC) and thermogravimetry‐derivative thermogravimetry (TG‐DTG) as well as the calculation of non‐isothermal kinetic parameters. Consequently, both salts shown acceptable thermal stabilities as the decomposition temperatures were over 200 °C. The enthalpies of formation were calculated for these salts using the measured combustion energies with a result of 70.6 kJ · mol^–1 for 1 and –47.8 kJ · mol^–1 for 2 , respectively. Impact and friction sensitivities were also tested and the results indicated that these salts both have low sensitivities (>40 J, 120 N). The title energetic salts possess acceptable performance, they can therefore be applied in the field of energetic materials.     

Synthesis,Structure, Chemical and Energetic Characterization of 1,3‐Dinitramino‐2‐nitroxy‐propane

The title compound, 1,3‐dinitramino‐2‐nitroxy‐propane ( 1 ) was prepared in high yield (85 %) and characterized by multinuclear NMR (¹H, ¹³C, ¹⁴N) and vibrational (IR, Raman) spectroscopy. The molecular structure in the solid state was elucidated by single crystal X‐ray diffraction. 1 crystallizes in the orthorhombic space group P_nma with a crystal density of ρ = 1.798 g cm^?3. Compound 1 melts at 166 °C and decomposes at 168 °C. The impact (7 J), friction (96 N) and electrostatic discharge sensitivities (0.6 J) were determined experimentally. The detonation parameters of 1 were calculated using a combined quantum chemical (CBS‐4M) calculation and a chemical equilibrium calculation based on the steady‐state model of detonation: Q = ?5998 kJ kg^?1, P = 339 kbar, D = 8895 m s^?1. The experimentally determined detonation velocity (fiber optic method) agrees well with the calculated values. In comparison with picric acid (PA) and nitropenta (PETN), compound 1 shows superior detonation characteristics when detonated in a confined space.     

Synthesis,Crystal Structure,and Properties of Energetic Complex Magnesium 5,5′‐Dinitramino‐3,3′‐bi[1,2,4‐triazolate] Hexahydrate

Alkaline Earth metal (Mg) energetic complex with 5,5′‐dinitramino‐3,3′‐bi[1,2,4‐triazolate] dihydrate (DNABT) has been synthesized and structurally characterized by FTIR spectroscopy, elemental analysis, and single X‐ray diffraction. The thermal decomposition processes of the complex and DNABT were studied by means of the TDA‐TG technologies. Sensitivity tests reveal that the complex is more insensitive to mechanical stimuli than DNABT. Combustion behavior shows that 1 has good color performances.     

Synthesis and Characteristics of Bis(2, 2‐dinitroethyl‐N‐nitro)ethylenediamine‐Based Energetic Salts

New energetic bis(2, 2‐dinitroethyl‐N‐nitro)ethylenediamine‐based salts exhibiting moderate physical properties, good detonation properties, and relatively low impact sensitivities were synthesized in high yield by direct reactions of bis(2, 2‐dinitroethyl‐N‐nitro)ethylenediamine with organic bases. The resulting salts were fully characterized by multinuclear NMR spectroscopy (¹H and ¹³C), vibrational spectroscopy (IR), differential scanning calorimetry (DSC), and elemental analysis. Solid‐state ¹⁵N NMR spectroscopy was used as an effective technique to further determine the structure of some products. Thermal decomposition kinetics and several thermodynamic parameters of some salts were obtained under non‐isothermal conditions by DSC. The densities of the energetic salts paired with organic cations were in the range 1.60–1.89 g · cm^–3 as measured with a gas pycnometer. Based on the measured densities and calculated heats of formation, detonation pressures and velocities were calculated using Explo 5.05 and found to be 23.6–44.8 GPa and 7790–9583 m · s^–1, respectively, which make them potentially useful as energetic materials.     

Syntheses and Promising Properties of Dense Energetic 5,5′‐Dinitramino‐3,3′‐azo‐1,2,4‐oxadiazole and Its Salts

A planar energetic molecule with high density, 5,5′‐dinitramino‐3,3′‐azo‐1,2,4‐oxadiazole ( 4 ), was obtained by the nitration of 5,5′‐diamino‐3,3′‐azo‐1,2,4‐oxadiazole using 100 % nitric acid. In addition, selected nitrogen‐rich salts were prepared. Of them, the neutral compound 4 and its hydroxylammonium salt, 6 , were further confirmed by single‐crystal X‐ray diffraction. Physicochemical and energetic properties including density, thermal stability, and sensitivity were investigated. The energetic performance from the calculated heats of formation and experimental densities indicates that many of them have potential applications as energetic materials.     

Synthesis,Characterization, and Energetic Properties of 6‐Amino‐tetrazolo[1,5‐b]‐1,2,4,5‐tetrazine‐7‐N‐oxide: A Nitrogen‐Rich Material with High Density

The synthesis and energetic properties of a novel N‐oxide high‐nitrogen compound, 6‐amino‐tetrazolo[1,5‐b]‐1,2,4,5‐tetrazine‐7‐N‐oxide, are described. Resulting from the N‐oxide and fused rings system, this molecule exhibits high density, excellent detonation properties, and acceptable impact and friction sensitivities, which suggests potential applications as an energetic material. Compared to known high‐nitrogen compounds, such as 3,6‐diazido‐1,2,4,5‐tetrazine (DiAT), 2,4,6‐tri(azido)‐1,3,5‐triazine (TAT), and 4,4′,6,6′‐tetra(azido)azo‐1,3,5‐triazine (TAAT), a marked performance and stability increase is seen. This supports the superior qualities of this new compound and the advantage of design strategy.     

2‐(Dinitromethylene)‐1‐nitro‐1, 3‐diazacyclopentane‐Based Energetic Salts

Energetic salts that contain nitrogen‐rich cations and the 2‐(dinitromethyl)‐3‐nitro‐1, 3‐diazacyclopent‐1‐ene anion were synthesized in high yield by direct neutralization reactions. The resulting salts were fully characterized by multinuclear NMR spectroscopy (¹H and ¹³C), vibrational spectroscopy (IR), elemental analysis, density and differential scanning calorimetry (DSC), and elemental analysis. Additionally, the structures of the ammonium ( 1 ) and isopropylideneaminoguanidinium ( 9 ) 2‐(dinitromethyl)‐3‐nitro‐1, 3‐diazacyclopent‐l‐ene salts were confirmed by single‐crystal X‐ray diffraction. Solid‐state ¹⁵N NMR spectroscopy was used as an effective technique to further determine the structure of some of the products. The densities of the energetic salts paired with organic cations fell between 1.50 and 1.79 g · cm^–3 as measured by a gas pycnometer. Based on the measured densities and calculated heats of formation, detonation pressures and velocities were calculated using Explo 5.05 and found to to be 25.2–35.5 GPa and 7949–9004 m · s^–1, respectively, which make them competitive energetic materials.     

Energetic Oxygen‐Containing Tetrazole Salts Based on 3,4‐Diaminotriazole

Energetic mono‐ and dicationic 3,4‐diaminotriazolium salts have been prepared by combining stoichiometric amounts (1:1 or 2:1 molar ratio) of 3,4‐diaminotriazole with various oxygen‐containing tetrazoles, and the structures have been confirmed by single‐crystal XRD for the first time. All structures are dominated by a strong hydrogen‐bond network owing to both amino groups and oxygen in the molecule. All salts, except 7 , exhibit excellent thermal stabilities with decomposition temperatures over 200 °C. Based on experimental densities and theoretical calculations carried out by using the Gaussian 03 suite of programs, all salts have calculated detonation pressures (20.3–33.9 GPa) and velocities (7095–8642 m s^?1).     

Ab initio conformational analysis of 1,5‐dithiacyclooctane, 1,5‐diselenacyclooctane,and 1,5‐ditelluracyclooctane

Energy‐minimum structures of 1,5‐dithiacyclooctane (1,5‐DTCO), 1,5‐diselenacyclooctane (1,5‐DSeCO), and 1,5‐ditelluracyclooctane (1,5‐DTeCO) were calculated by the ab initio molecular orbital method. Nine energy‐minimum structures were obtained for each compound. A twist‐boat–chair (TBC) structure is the most stable for 1,5‐DTCO and 1,5‐DSeCO, whereas a boat–boat (BB) structure is the most stable in 1,5‐DTeCO. The TBC conformer of 1,5‐DTCO has received little attention so far. The energy gap between HOMO and NHOMO in the TBC conformer of 1,5‐DTCO is in good agreement with the experimental data (photoelectron spectrum). For 1,5‐DTCO and 1,5‐DSeCO, the boat–chair (BC) conformer in which two chalcogen atoms face each other has the highest HOMO energy among the nine conformers, and the energy barriers between the TBC and BC conformers were calculated to be relatively low for these compounds. Therefore, a conformational change from the TBC to the BC is predicted to occur before these compounds are oxidized in solution. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 159–166, 1999     

Insensitive and Thermostable Energetic Materials Based on 3‐Ureido‐4‐tetrazole‐furazan: Synthesis,Characterization, and Properties

Energetic salts composed of ureido, furazan, and tetrazole were prepared by simple and efficient chemical routes to explore new insensitive and thermostable energetic materials. 3‐Ureido‐4‐tetrazole‐furazan ( 3 ) and its ammonium salt ( 5 ) and hydrazinium salt ( 6 ) were confirmed by single‐crystal X‐ray diffraction. The thermal stabilities of the synthesized salts were studied using differential scanning calorimetry, and the detonation performances of these salts were calculated using EXPLO 5 V6.01. All the salts exhibit good thermal stability (Td: 148–259 °C) and mechanical sensitivities (IS > 40 J, FS > 360 N), and their detonation velocities range from 7316 to 8655 m · s^–1. Compounds 6 and 10 are potential candidates as novel insensitive and heat‐resistant explosives because of their high detonation temperatures of 247 and 256 °C, good detonation velocities of 8432 and 8523 m · s^–1, and good detonation pressures of 25.6 and 26.8 GPa.     

Unusual Energetic Periodate,Sulfate and Amino-bistetrazolate Salts of the Trinitropropylammonium Cation

Starting from a nucleophilic Michael addition of nitroform to acrylamide, three synthetic strategies towards 1,1,1-trinitropropyl-1-ammonium salts are described. Due to the high oxygen content and density of one periodate salt, its suitability as high-energy dense oxidizer in energetic formulations was predicted according to its specific impulse and detonation velocity. Furthermore, those properties were compared to the nitrogen-rich amino-bis(5-tetrazolate) salt. The parameters were calculated with the EXPLO5 (V6.03) computer code and compared to the common solid rocket propellant ammonium perchlorate (AP). Calculations towards the energies of formation were performed using Gaussian 09. Characterization including multinuclear NMR spectroscopy, vibrational analysis (IR, Raman) as well as elemental analysis and a single-crystal X-ray diffraction study was performed. The thermal stability was studied using differential scanning calorimetry and the sensitivities against impact and friction were determined.