Initial Thermal Decomposition Mechanism of (NH2)2C=C(NO2)(ONO) Revealed by Double-Hybrid Density Functional Calculations.

This work employs double-hybrid density functionals to re-examine the CO-NO bond dissociation mechanism of nitrite isomer of 1,1-diamino-2,2-dinitro-ethylene (DADNE) into (NH2)2C=C(NO2)O and nitric monoxide (NO). The calculated results confirm that an activated barrier is present in the CO-NO bond dissociation process of (NH2)2C=C(NO2)(ONO). Furthermore, it is proposed that a radical-radical adduct is involved in the exit dissociation path with subsequent dissociation to separate (NH2)2C=C(NO2)O and NO radicals. The activation and reaction enthalpies at 298.15 K for the nitrite isomer dissociation are predicted to be 43.6 and 5.4 kJ mol-1 at the B2PLYP/6-31G(d,p) level, respectively. Employing the B2PLYP/6-31G(d,p) reaction energetics, gradient, Hessian, and geometries, the kinetic model for the CO-NO bond dissociation of (NH2)2C=C(NO2)(ONO) is obtained by a fitting to the modified Arrhenius form 1.05 × 1013(T/300)0.39 exp[-27.80(T + 205.32)/R(T 2 + 205.322)] in units of per second over the temperature range 200-3000 K based on the canonical variational transition-state theory with multidimensional small-curvature tunneling.

Theoretical mechanistic study on the reaction of the methoxymethyl radical with nitrogen dioxide.

Mechanism of the reaction of CH3OCH2 with NO2 is explored theoretically at the M062X/MG3S and G4 levels. The calculated results indicate two stable association intermediates, CH3OCH2NO2 (IM1) and CH3OCH2ONO (IM2), which can be produced by the attack of the nitrogen or oxygen atom of NO2 to terminal carbon atom of CH3OCH2 without barrier involved. IM2 is found to take trans (IM2a)-cis (IM2b) conversion and isomerization to IM1, with the following stability order IM2a > IM2b > IM1. Starting from IM2a, the most feasible pathway is the direct O-NO bond cleavage leading to P1 (CH3OCH2O + NO) or the H-shift and O-NO bond rupture to produce P2 (CH3OCHO + HNO), both of which have comparable contribution to the title reaction. There also involves an H-transfer from the methyl group of IM2a to the N atom with the simultaneous dissociations of the C-O and O-N bonds to produce P4 (2CH2O + HNO). In addition, another dissociation pathway is open to IM2b which decompose to P5 (CH2O + CH3ONO) by the O-N and C-O bond scissions and the recombination of CH3O and NO. Because all the intermediates and transition states involved in the above pathways lie below reactants, the CH3OCH2 + NO2 reaction is expected to be rapid. Subsequent dissociation of IM1 and direct H-abstraction between CH3OCH2 and NO2 are kinetically almost inhibited due to significantly high barriers. The present results can lead us to deeply understand the mechanism of the title reaction and may be helpful for understanding NO2 combustion chemistry.

Synthesis, Crystal Structure, Biological Evaluation and in Silico Studies on Novel (E)-1-(Substituted Benzylidene)-4-(3-isopropylphenyl)thiosemicarbazone Derivatives.

A series of (E)-1-(substituted benzylidene)-4-(3-isopropylphenyl)thiosemicarbazone derivatives were synthesized and characterized by FT-IR spectrum, elemental analysis, NMR spectrum, HR-MS spectrum, and X-ray single crystal diffraction technology. The crystal structures and packing of (E)-1-(4-fluorobenzylidene)-4-(3-isopropylphenyl)thiosemicarbazone and (E)-1-(3-fluorobenzylidene)-4-(3-isopropylphenyl)thiosemicarbazone were maintained through the intramolecular hydrogen bond (N3-H6⋅⋅⋅N1) and intermolecular hydrogen bonds (N2-H4⋅⋅⋅S1, C14-H14⋅⋅⋅F1 and C7-H7⋅⋅⋅S1). The results obtained by employing the DPPH free radicals scavenging assay indicated that (E)-1-(4-methoxylbenzylidene)-4-(3-isopropylphenyl)thiosemicarbazone had a more significant antioxidant activity compared with other compounds. The results measured by adopting the disc diffusion method elucidated that (E)-1-(4-trifluoromethylbenzylidene)-4-(3-isopropylphenyl)thiosemicarbazone possessed a more prominent antifungal activity than other compounds. Molecular docking showed that (E)-1-(4-chlorobenzylidene)-4-(3-isopropylphenyl)thiosemicarbazone had the highest affinity with receptor protein (1NMT). Moreover, the drug-likeness characteristic, physicochemical properties, pharmacokinetic profiles, and bioactivity scores of all the compounds were predicted through in silico studies. The results illustrated that (E)-1-(4-fluorobenzylidene)-4-(3-isopropylphenyl)thiosemicarbazone had the drug-likeness characteristic and all the compounds were considered as moderately biological active molecules.

Investigation on the Thermal Dissociation of Vinyl Nitrite with a Saddle Point Involved.

Hybrid and double-hybrid density functionals are employed to explore the O-NO bond dissociation mechanism of vinyl nitrite (CH2=CHONO) into vinoxy (CH2=CHO) and nitric monoxide (NO). In contrast to previous investigations, which point out that the O-NO bond dissociation of vinyl nitrite is barrierless, our computational results clearly reveal that a kinetic barrier (first-order saddle point) in the O-NO bond dissociation is involved. Furthermore, a radical-radical adduct is recommended to be present on the dissociation path. The activation and reaction enthalpies at 298.15 K for the vinyl nitrite dissociation are calculated to be 91 and 75 kJ mol-1 at the M062X/MG3S level, respectively, and the calculated reaction enthalpy compares very well with the experimental result of 76.58 kJ mol-1. The M062X/MG3S reaction energetics, gradient, Hessian, and geometries are used to estimate vinyl nitrite dissociation rates based on the multistructural canonical variational transition-state theory including contributions from hindered rotations and multidimensional small-curvature tunneling at temperatures from 200 to 3000 K, and the rate constant results are fitted to the four-parameter Arrhenius expression of 4.2 × 109 (T/300)4.3 exp[-87.5(T - 32.6)/(T 2 + 32.62)] s-1.

Computational Study of the Reaction of Dimethyl Ether with Nitric Oxide. Mechanism and Kinetic Modeling.

To probe into the autoignition effect of nitric oxide (NO) on the combustion of dimethyl ether (DME), a detailed mechanism study and kinetic modeling for the reaction of DME with NO, which was considered to be very sensitive to the ignition delay time of DME, have been conducted using computational chemical methods. The CCSD(T)/6-311+G(2df,2p)//B2PLYP/TZVP compound method was employed to obtain the potential energy surface along the reaction coordinate, with the geometries, gradients, and force constants of nonstationary points calculated at the B2PLYP/TZVP theoretical level. The temperature-dependent rate coefficients from 200 to 3000 K were calculated using multistructural canonical variational transition-state theory (MS-CVT) with torsional motions and multidimensional tunneling effects included. The CCSD(T) calculations with both 6-311+G(2df,2pd) and cc-pVTZ basis sets give a zero-point inclusive barrier of 197-201 kJ mol-1 using the BMK/MG3S, B2PLYP/TZVP, and mPW2PLYP/TZVP based geometries. A van der Waals postreaction complex appears on the products HNO + CH3OCH2 side of the transition state. Two highly coupled torsions lead to four conformers for the transition state, and contributions from multiple structures and torsional anharmonicities substantially affect the rate coefficient evaluations. Variational effects can be argued to play an important role, especially at high temperatures, and tunneling probabilities increase with decreasing temperature. Because of large temperature-dependent feature of activation energy, the four-parameter formula 1.912 × 1011( T/300)3.191 exp[-178.417( T - 2.997)/( T2 + 2.9972)] cm3 mol-1 s-1 is recommended for the MS-CVT calculated rate coefficients including small-curvature tunneling. The kinetic model is shown to give a satisfactory interpretation of the inhibited and accelerated effect of NO on the oxidation of DME.

Synthesis, crystal structure and thermal properties of an unsymmetrical 1,2,4,5-tetrazine energetic derivative.

A new unsymmetrical s-tetrazine derivative, namely 4-({2-[6-(3,5-dimethyl-1H-pyrazol-1-yl)-1,2,4,5-tetrazin-3-yl]hydrazin-1-ylidene}methyl)phenol (DPHM), C14H14N8O, was synthesized based on 3-(3,5-dimethylpyrazol-1-yl)-6-hydrazinyl-s-tetrazine (DPHT). The structure was characterized by elemental analysis and single-crystal X-ray diffraction. Crystal structure determination shows that DPHM crystallizes in the monoclinic P21/c space group with high coplanarity and a zigzag layered structure. In addition, its thermal behaviour was investigated by DSC and TG-DTG methods. The thermal safety of DPHM was evaluated by self-accelerating decomposition temperature (TSADT), critical temperature of thermal explosion (Tb), entropy of activation (ΔS=), enthalpy of activation (ΔH=) and free energy of activation (ΔG=). Meanwhile, the kinetic parameters and specific heat capacity of DPHM were also determined. The results show that DPHM has better stability and detonation properties than 3-(2-benzylidenehydrazin-1-yl)-6-(3,5-dimethylpyrazol-1-yl)-s-tetrazine (DAHBTz), due to the introduction of a hydroxy group, which increases the number of hydrogen-bond interactions and improves the stability and density of DPHM. This study demonstrates that the performance of an explosive can be optimized through structural modification.

Theoretical study of a series of 4,4'-azo-1H-1,2,4-triazol-5-one based nitrogen-rich salts as potential energetic compounds.

Density function theory has been employed to systemically study 4,4'-azo-1H-1,2,4-triazol-5-one (ZTO) and its six nitrogen-rich salts at two different calculated levels (B3LYP/6-31G(d,p) and B3PW91/6-31G(d,p)). Their optimized geometries, electronic structures and molecular electrostatic potentials were further studied. Based on the two computed methods, the results of the optimized geometries show that the calculated structure of each compound adopted at the two different levels are rather similar except salt 7 with some differences. The values of the energy gaps indicate that compound 3 has the highest reactivity among salts 2-7. The crystal densities were corrected using the Politzer approach based on these two optimized levels. The density values with slight deviation indicate that the two calculated levels are applicable and the results are convincible. Based on the isodesmic reactions and Born-Haber energy cycle, the solid-phase heats of formation (HOFs) were predicted. Detonation parameters were evaluated using the Kamlet-Jacobs equations on the foundations of the calculated densities and HOFs. The results manifest that salt 2 exhibits the best detonation performance due to its highest density (1.819 g cm-3), followed by salt 6. Moreover, impact sensitivities of compounds 1-7 were assessed using the calculated Q values to correlate with h 50. Combining the detonation performance with safety, 1-7 exhibit good comprehensive properties and might be screened as a composition of modern nitrogen-rich energetic compounds.

Two Cu(ii)-triadimenol complexes as potential fungicides: synergistic actions and DFT calculations.

Two Cu(ii) complexes, namely, [CuL4(H2O)2]·2NO3·2CH3OH 1 and [CuL2(CH3COO)2] 2, (L = (1S,2R)-1-(4-chlorophenoxy)-3,3-dimethyl-1-(1,2,4-triazol-1-yl)butan-2-ol, triadimenol, a commercial 1,2,4-triazole pesticide) were synthesized and characterized by elemental analysis, IR spectra, UV-Vis spectra and single crystal X-ray diffraction. Crystal structural analysis shows that the different types of salts (copper acetate is covalent, while copper nitrate is ionic) contribute to different crystal structures: complex 1 consists of one copper cation, four ligands, two coordinated water molecules, two free nitrate anions and two uncoordinated methanol molecules. Complex 2 is composed of one copper cation, two ligands and two acetate anions, without free molecules. The two complexes and the ligand triadimenol were also screened for antifungal activities against four selected fungi. The antifungal results reveal that both the complexes show better bioactivities in comparison with L, and that complex 1 has higher bioactivities than complex 2. To elaborate the reasons of the enhanced bioactivities after complexation, the interaction levels between Cu2+ cation and triadimenol, as well as the density functional theory (DFT) method were carried out. The results indicate that three factors made the antifungal activities stronger after forming Cu(ii) complexes: new active site of copper cation, synergic interactions between Cu2+ cation and L, and improved penetration of the metal complexes into the lipid membranes.

Variational Effect and Anharmonic Torsion on Kinetic Modeling for Initiation Reaction of Dimethyl Ether Combustion.

The reaction of dimethyl ether (DME) with molecular oxygen has been considered to be the dominant initiation pathway for DME combustion compared to the C-O bond fission. This work presents a detailed mechanism and kinetics investigation for the O2 + DME reaction with theoretical approaches. Using the CCSD(T)/6-311+G(2df,2pd) potential energy surface with the M06-2X/MG3S gradient, Hessian, and geometries, rate constants are evaluated by multistructural canonical variational transition-state theory (MS-CVT) including contributions from hindered rotation and multidimensional tunneling over the temperature range 200-2800 K. The CCSD(T) and QCISD(T) with 6-311+G(2df,2pd) calculations predict a barrier of 190-194 kJ mol-1 for the O2 + DME reaction based on the optimized structures at various levels. It is proposed that there exists a weakly interacting adducts on the product side with subsequent dissociation to the separate HO2 and CH3OCH2 radicals. Torsions in transition state are found to be significantly coupled to generate four conformations whose contributions do influence the rate constant predictions. Variational effects are observed to be significant at high temperatures, while tunneling effect quickly becomes insignificant with temperature. Finally, four-parameter Arrhenius expression 9.14 × 1013(T/300)-3.15 exp[-184.52(T + 110.23)/(T2 + 110.232)] cm3 mol-1 s-1 describes the temperature dependence of MS-CVT rate constants with small-curvature tunneling correction.

Synthesis and crystal structure of a two-dimensional sodium coordination polymer of 4,4'-(diazenediyl)bis(1H-1,2,4-triazol-5-one).

The crystal engineering of coordination polymers has aroused interest due to their structural versatility, unique properties and applications in different areas of science. The selection of appropriate ligands as building blocks is critical in order to afford a range of topologies. Alkali metal cations are known for their mainly ionic chemistry in aqueous media. Their coordination number varies depending on the size of the binding partners, and on the electrostatic interaction between the ligands and the metal ions. The two-dimensional coordination polymer poly[tetra-µ-aqua-[µ4-4,4'-(diazenediyl)bis(5-oxo-1H-1,2,4-triazolido)]disodium(I)], [Na2(C4H2N8O2)(H2O)4]n, (I), was synthesized from 4-amino-1H-1,2,4-triazol-5(4H)-one (ATO) and its single-crystal structure determined. The mid-point of the imino N=N bond of the 4,4'-(diazenediyl)bis(5-oxo-1H-1,2,4-triazolide) (ZTO(2-)) ligand is located on an inversion centre. The asymmetric unit consists of one Na(+) cation, half a bridging ZTO(2-) ligand and two bridging water ligands. Each Na(+) cation is coordinated in a trigonal antiprismatic fashion by six O atoms, i.e. two from two ZTO(2-) ligands and the remaining four from bridging water ligands. The Na(+) cation is located near a glide plane, thus the two bridging O atoms from the two coordinating ZTO(2-) ligands are on adjacent apices of the trigonal antiprism, rather than being in an anti configuration. All water and ZTO(2-) ligands act as bridging ligands between metal centres. Each Na(+) metal centre is bridged to a neigbouring Na(+) cation by two water molecules to give a one-dimensional [Na(H2O)2]n chain. The organic ZTO(2-) ligand, an O atom of which also bridges the same pair of Na(+) cations, then crosslinks these [Na(H2O)2]n chains to form two-dimensional sheets. The two-dimensional sheets are further connected by intermolecular hydrogen bonds, giving rise to a stabile hydrogen-bonded network.

A new Co(II) complex of diniconazole: synthesis, crystal structure and antifungal activity.

A new Co(II) complex of diniconazole, namely diaqua[(E)-(RS)-1-(2,4-dichlorophenyl)-4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl-κN(4))pent-1-en-3-ol]cobalt(II) dinitrate dihydrate, [Co(C15H17Cl2N3O)3(H2O)2](NO3)2·2H2O, was synthesized and characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. Crystal structural analysis shows that the centrosymmetric Co(II) cation is coordinated by four diniconazole ligands and two water molecules, forming a six-coordinated octahedral structure. There are also two free nitrate counter-anions and two additional solvent water molecules in the structure. Intermolecular O-H...O hydrogen bonds link the complex cations into a one-dimensional chain. In addition, the antifungal activity of the complex against Botryosphaeria ribis, Gibberella nicotiancola, Botryosphaeria berengriana and Alternariasolani was studied. The results indicate that the complex shows a higher antifungal activity for Botryosphaeria ribis and Botryosphaeria berengriana than diniconazole, but a lower antifungal activity for Gibberella nicotiancola and Alternariasolani.

Near-infrared luminescent PMMA-supported metallopolymers based on Zn-Nd Schiff-base complexes.

On the basis of self-assembly from the divinylphenyl-modified Salen-type Schiff-base ligands H2L(1) (N,N'-bis(5-(3'-vinylphenyl)-3-methoxy-salicylidene)ethylene-1,2-diamine) or H2L(2) (N,N'-bis(5-(3'-vinylphenyl)-3-methoxy-salicylidene)phenylene-1,2-diamine) with Zn(OAc)2·2H2O and Ln(NO3)3·6H2O in the presence of pyridine (Py), two series of heterobinuclear Zn-Ln complexes [Zn(L(n))(Py)Ln(NO3)3] (n = 1, Ln = La, 1; Ln = Nd, 2; or Ln = Gd, 3 and n = 2, Ln = La, 4; Ln = Nd, 5; or Ln = Gd, 6) are obtained, respectively. Further, through the physical doping and the controlled copolymerization with methyl methacrylate (MMA), two kinds of PMMA-supported hybrid materials, doped PMMA/[Zn(L(n))(Py)Ln(NO3)3] and Wolf Type II Zn(2+)-Ln(3+)-containing metallopolymers Poly(MMA-co-[Zn(L(n))(Py)Ln(NO3)3]), are obtained, respectively. The result of their solid photophysical properties shows the strong and characteristic near-infrared (NIR) luminescent Nd(3+)-centered emissions for both PMMA/[Zn(L(n))(Py)Nd(NO3)3] and Poly(MMA-co-[Zn(L(n))(Py)Nd(NO3)3]), where ethylene-linked hybrid materials endow relatively higher intrinsic quantum yields due to the sensitization from both (1)LC and (3)LC of the chromorphore than those from only (1)LC in phenylene-linked hybrid materials, and the concentration self-quenching of Nd(3+)-based NIR luminescence could be effectively prevented for the copolymerized hybrid materials in comparison with the doped hybrid materials.

Thermolysis, nonisothermal decomposition kinetics, specific heat capacity and adiabatic time-to-explosion of [Cu(NH3)4](DNANT)2 (DNANT= dinitroacetonitrile).

A new energetic copper complex of dinitroacetonitrile (DNANT), [Cu(NH3)4](DNANT)2, was first synthesized through an unexpected reaction. The thermal decomposition of [Cu(NH3)4](DNANT)2 was studied with DSC and TG/DTG methods. The gas products were analyzed through a TG-FTIR-MS method. The nonisothermal kinetic equation of the exothermic process is dα/dT = 10(10.92)/ß4(1 - α)[-ln(1 - α)](3/4) exp(-1.298 × 10(5)/RT). The self-accelerating decomposition temperature and critical temperature of thermal explosion are 217.9 and 221.0 °C. The specific heat capacity of [Cu(NH3)4](DNANT)2 was determined with a micro-DSC method, and the molar heat capacity is 512.6 J mol(-1) K(-1) at 25 °C. Adiabatic time-to-explosion of Cu(NH3)4(DNANT)2 was also calculated to be about 137 s.

Anion-induced self-assembly of luminescent and magnetic homoleptic cyclic tetranuclear Ln4(salen)4 and Ln4(salen)2 complexes (Ln = Nd, Yb, Er, or Gd).

Unique homoleptic cyclic tetranuclear Ln(4)(Salen)(4) complexes [Ln(4)(L)(2)(HL)(2)(µ(3)-OH)(2)Cl(2)]·2Cl (Ln = Nd, 1; Ln = Yb, 2; Ln = Er, 3; Ln = Gd, 4) or Ln(4)(Salen)(2) complexes [Ln(4)(L)(2)(µ(3)-OH)(2)(OAc)(6)] (Ln = Nd, 5; Ln = Yb, 6; Ln = Er, 7; Ln = Gd, 8) have been self-assembled from the reaction of the hexadentate Salen-type Schiff-base ligand H(2)L with LnCl(3)·6H(2)O or Ln(OAc)(6)·6H(2)O (Ln = Nd, Yb, Er, or Gd), respectively (H(2)L: N,N'-bis(salicylidene)cyclohexane-1,2-diamine). The result of their photophysical properties shows that the strong and characteristic NIR luminescence for complexes 1-2 and 5-6 with emissive lifetimes in microsecond ranges are observed, and the sensitization arises from the excited state (both (1)LC and (3)LC) of the hexadentate Salen-type Schiff-base ligand with the flexible linker. Temperature dependence (1.8-300 K) magnetic susceptibility studies of the eight complexes suggest the presence of an antiferromagnetic interaction between the Ln(3+) ions.

catena-Poly[(chloridozinc)-µ-5-(1-methyl-1H-benzimidazol-2-yl-κN(3))-1,2,3-triazol-1-ido-κ(2)N(1):N(3)].

In the title complex, [Zn(C(10)H(8)N(5))Cl](n), the Zn(II) ion is four-coordinated by one Cl atom and three N atoms from two in situ-generated deprotonated 5-(1-methyl-1H-benzimidazol-2-yl-κN(3))-1,2,3-triazol-1-ide ligands in a slightly distorted tetra-hedral geometry. The Zn(II) ions are bridged by the ligands, forming a helical chain along [001]. C-H⋯N and C-H⋯Cl hydrogen bonds and π-π inter-actions between the imidazole rings [centroid-centroid distance = 3.4244 (10) Å] assemble the chains into a three-dimensional supra-molecular network.

Preparation, non-isothermal decomposition kinetics, heat capacity and adiabatic time-to-explosion of NTOxDNAZ.

NTOxDNAZ was prepared by mixing 3,3-dinitroazetidine (DNAZ) and 3-nitro-1,2,4-triazol-5-one (NTO) in ethanol solution. The thermal behavior of the title compound was studied under a non-isothermal condition by DSC and TG/DTG methods. The kinetic parameters were obtained from analysis of the DSC and TG/DTG curves by Kissinger method, Ozawa method, the differential method and the integral method. The main exothermic decomposition reaction mechanism of NTOxDNAZ is classified as chemical reaction, and the kinetic parameters of the reaction are E(a)=149.68 kJ mol(-1) and A=10(15.81)s(-1). The specific heat capacity of the title compound was determined with continuous C(p) mode of microcalorimeter. The standard mole specific heat capacity of NTOxDNAZ was 352.56 J mol(-1)K(-1) in 298.15K. Using the relationship between C(p) and T and the thermal decomposition parameters, the time of the thermal decomposition from initialization to thermal explosion (adiabatic time-to-explosion) was obtained.

1-(2,4-Dinitro-phen-yl)-3,3-dinitro-azetidine.

In the title compound, C(9)H(7)N(5)O(8), the dihedral angle between the mean plane of the azetidine ring and that of the benzene ring is 26.1 (1)°; the planes of the two nitro groups of the azetidine ring are aligned at 88.7 (1)°.

1-Benzoyl-3,3-dinitro-azetidine.

In the title gem-dinitro-azetidine derivative, C(10)H(9)N(3)O(5), the azetidine ring is almost planar, the maximum value of the endocyclic torsion angle being 0.92 (14)°. The gem-dinitro groups are mutually perpendicular and the dihedral angle between the azetidine and benzene rings is 46.70 (10)°

Thermal behavior, specific heat capacity and adiabatic time-to-explosion of G(FOX-7).

[H(2)N=C(NH(2))(2)](+)(FOX-7)(-)-G(FOX-7) was prepared by mixing FOX-7 and guanidinium chloride solution in potassium hydroxide solution. Its thermal decomposition was studied under the non-isothermal conditions with DSC and TG/DTG methods. The apparent activation energy (E) and pre-exponential constant (A) of the two exothermic decomposition stages were obtained by Kissinger's method and Ozawa's method, respectively. The critical temperature of thermal explosion (T(b)) was obtained as 201.72 degrees C. The specific heat capacity of G(FOX-7) was determined with Micro-DSC method and theoretical calculation method and the standard molar specific heat capacity is 282.025 J mol(-1) K(-1) at 298.15 K. Adiabatic time-to-explosion of G(FOX-7) was also calculated to be a certain value between 13.95 and 15.66 s.

Nonisothermal decomposition kinetics and computational studies on the properties of 2,4,6,8-tetranitro-2,4,6,8-tetraazabicyclo[3,3,1]onan-3,7-dione (TNPDU).

The thermal decomposition and the nonisothermal kinetics of the thermal decomposition reaction of 2,4,6,8-tetranitro-2,4,6,8-tetraazabicyclo[3,3,1]onan-3,7-dione (TNPDU) were studied under the nonisothermal condition by differential scanning calorimetry (DSC) and thermogravimetry-derivative thermogravimetry (TG-DTG) methods. The kinetic model function in differential form and the value of Ea and A of the decomposition reaction of TNPDU are f(alpha) = 3(1 - alpha)[-ln(1 - alpha)](2/3), 141.72 kJ mol(-1), and 10(11.99) s(-1), respectively. The critical temperature of thermal explosion of the title compound is 232.58 degrees C. The values of DeltaS(++), DeltaH(++), and DeltaG(++) of this reaction are -15.50 J mol(-1) K(-1), 147.65 kJ mol(-1), and 155.26 kJ mol(-1), respectively. The theoretical investigation on the title compound as a structure unit was carried out by the DFT-B3LYP/6-311++G** method. The IR frequencies and NMR chemical shift were performed and compared with the experimental results. The heat of formation (HOF) for TNPDU was evaluated by designing isodesmic reactions. The detonation velocity (D) and detonation pressure (P) were estimated by using the well-known Kamlet-Jacobs equation, based on the theoretical densities and HOF. The calculation on bond dissociation energy suggests that the N-N bond should be the trigger bond during the pyrolysis initiation process.