Bi‐Dong Wu

Preparation, crystal structures, thermal decompositions and explosive properties of two new high-nitrogen azide ethylenediamine energetic compounds

Two new multi-ligand coordination compounds of copper(II) ethylenediamine (en) azide and cobalt(III) ethylenediamine azide, [Cu2(en)2(N3)4]n (1) and Co(en)2(N3)2(NO3) (2), were synthesized and characterized by elemental analysis and FT-IR spectroscopy. The crystal structures were determined by X-ray single crystal diffraction. The obtained results show that the crystals of 1 and 2 belong to the monoclinic, C2/c space group. The metal cations are six-coordinated with the azido ligands and ethylenediamine molecules through nitrogen atoms. The coordination modes of the azido-groups were μ-1, μ-1,1 and μ-1,1,3 modes for 1, and μ-1 mode for 2. Under a nitrogen atmosphere, with a heating rate of 5 K min−1, the thermal decompositions contain two main exothermic stages in the DSC curves corresponding to the TG-DTG curves. The non-isothermal kinetics parameters were calculated by the Kissingers method and Ozawas method, respectively. The energies of combustion, enthalpies of formation, critical temperature of thermal explosion, entropies of activation (ΔS≠), enthalpies of activation (ΔH≠), and free energies of activation (ΔG≠) were measured and calculated. The sensitivity properties were also determined with standard methods and the results showed that 1 had a much higher flame sensitivity and lower impact sensitivity.

Synthesis, structure, and thermal decomposition of two copper coordination compounds [Cu(DAT)2(PA)2] and [Cu(DAT)2(HTNR)2] with nitrogen rich 1,5-diaminotetrazole (DAT)

Both [Cu(DAT)2(PA)2] (1) and [Cu(DAT)2(HTNR)2] (2) were prepared from 1,5-diaminotetrazole (DAT) and copper trinitrophenol, 1 for picrate (PA) and 2 for styphnate acid (2,4,6-trinitro resorcinol, TNR), and were characterized by elemental analysis, FT-IR spectroscopy, and single crystal X-ray diffraction. The space group of these compounds is P21/c (monoclinic). The lattice parameters are similar [a = 11.405(3) Å, b = 14.867(3) Å, c = 8.099(2) Å for 1 and a = 12.262(3) Å, b = 14.900(3) Å, c = 7.243(2) Å for 2], except the β = 106.257(3)° in 1 and β = 92.989(4)° in 2. Both have extended structures due to hydrogen bonds, but there are some differences because of the ligands induced effect. Differential scanning calorimetry analysis shows that two exothermic processes take place in both complexes, the first peak temperatures are 488.2 K for 1 and 519.2 K for 2. The kinetic parameters of the first exothermic process were studied by using Kissinger’s method and Ozawa’s method, in which the enthalpy of formation (−7346 and −5706 kJ M−1), critical temperature of thermal explosion (475.0 and 515.8 K), entropy of activation (ΔS≠), enthalpy of activation (ΔH≠), and free energy of activation (ΔG≠) were calculated and obtained as −117.25 J K−1 M−1, 140.64 kJ M−1, 196.44 kJ M−1 and −219.1 J K−1 M−1, 383.56 kJ M−1, 495.34 kJ M−1 for 1 and 2, respectively. The sensitivity test results showed that both compounds were sensitive to impact (<5 J) and flame (>20 cm) rather than friction. Two similar complexes combined with 1,5-diaminotetrazole (DAT) and copper trinitrophenol were characterized by elemental analysis, FT-IR spectroscopy and single crystal X-ray diffraction and the sensitivity were studied.

Preparation, crystal structure, and thermal decomposition of an azide energetic compound [Cd(IMI)2(N3)2]n (IMI = imidazole)

Cadmium(II) imidazole (IMI) azide [Cd(IMI)2(N3)2]n (1) was synthesized using imidazole and azide, and was characterized by the elemental analysis and FTIR spectrum. The crystal structure was determined by X-ray single crystal diffraction, and the crystallographic data show that the crystal belongs to orthorhombic, Pba2 space group, α = 10.780(4) Å, b = 13.529(5) Å, and c = 3.6415(12) Å. Its crystal density is 2.080 g·cm–3. Cd(II) is a six-coordinate with six nitrogens from four imidazoles and two azides with μ–1,1 coordination. The thermal decomposition mechanism was determined based on differential scanning calorimetry (DSC) and thermogravimetry-derivative thermogravimetry (TG-DTG) analysis, and the kinetic parameters of the first exothermic process were studied using Kissinger’s method and Ozawa’s method, respectively. The energy of combustion, enthalpy of formation, critical temperature of thermal explosion, entropy of activation (ΔS ≠), enthalpy of activation (ΔH ≠), and free energy of activation (ΔG ≠) were measured and calculated. In the end, impact sensitivity was also determined by standard method.

Energetic materials composed of coordination polymers: {[Zn(μ-atrz)3](ClO4)2·2H2O}n and {[Cu(μ-atrz)3](NO3)2·2H2O}n

An improved synthetic pathway for trans-4,4′-azo-1,2,4-triazole (atrz) was discovered. Pure atrz was obtained directly without any other separation step in an environment friendly process. Treatment of atrz with zinc perchlorate and cupric nitrate led to the isolation of {[Zn(μ-atrz)3](ClO4)2·2H2O}n and {[Cu(μ-atrz)3](NO3)2·2H2O}n, which were well characterized. Their structures were determined by X-ray crystallographic analysis. The calculation results of the formation of {[Zn(μ-atrz)3](ClO4)2 2H2O}n and {[Cu(μ-atrz)3](NO3)2 2H2O}n indicates that the perfect crystal structures in spite of much resistance. A fundamental understanding of the structure and thermal properties involves factors, such as conjugated system, crystal structure, and inorganic metallic compounds that affect their thermal behavior. The high energy of the coordination compounds consists of chemical, electronic, and potential energy. The potential for the improvement of the coordination polymer opens up a new world for research of energetic materials. Graphical Abstract

A novel compound [Mn(H2O)6](AMTZ)2(PA)2 (AMTZ = 4-amino-3,5-dimethyl-1,2,4-triazole and PA = Picrate) with Extensive hydrogen bonds: Synthesis, structure and thermal characters

The title compound 1, (Mn(H2O)6)(AMTZ)2(PA)2, contains 4-animo-3,5-dimethyl-1,2,4-triazole (AMTZ) and picrate (PA) and was characterized by elemental analysis, FT-IR spectroscopy and Single-Crystal X-ray diffraction. The space group of compound 1 is triclinic P-1(2), with a = 6.797(2) u A, b = 9.800(3) u A, c = 13.197(4) u A, =, =, =. The central Mn 2+ is octahedral and surrounded by two kinds of centrosymmetric molecules, AMTZ and PA. The compound has an extended 3-D supramolecular structure due to water molecules coordinated though hydrogen bonds to the nitrogen and oxygen atoms and the offset face-to- face π ··· π packing. The differential scanning calorimetry (DSC) analysis shows that two exothermic processes take place at 341.4 ◦ C and 473.9 ◦ C. The kinetic parameter of the first exothermic process was studied using Kissingers method and Ozawas method. This provided the enthalpy of formation (−3337.7 kJ·mol −1 ), critical temperature of thermal explosion (588.79 K). The entropy of activation (� S / = ), enthalpy of activation (� H / = ), and free energy of activation (� G / = ) were, respectively, -209.78 J·K −1 ·mol −1 , 155.50 kJ·mol −1 and 267.75 kJ·mol −1 . A flame sensitivity test showed that the 50% firing height (h50) was 20 cm.