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Ab initio investigation of the spectroscopic constants, bond dissociation energies of germanium monohalides, germanium dihalides and their ionic systems, viz. GeX, GeX−, GeX+, GeX2, GeX2− and GeX2+ (X = F, Cl, Br and I) have been carried out using correlation consistent triple-zeta basis sets for F and Cl and similar triple-zeta basis sets with RECPs for Ge, Br and I atoms. Geometry and frequency of all the neutral and ionic systems of germanium halides are obtained using MP2, CCSD(T) and QCISD(T) methods. The energetics are obtained at the CCSD(T)//MP2, QCISD(T)//MP2, CCSD(T) and QCISD(T) levels. Electron affinity (EA) and ionization potential (IP) of the monohalides and dihalides are reported to be consistent with the data available in literature. The bond dissociation energies (BDEs) to various dissociation asymptotes for most of the ionic systems are to be reported new in literature. The BDEs of the neutral germanium dihalides GeX2 are calculated by using the BDEs of GeX2− and GeX2+ ions and EA and IP of the associated neutral systems. A good agreement is found between the calculated values and the data wherever available. The BDEs of GeX2 for higher halogen member are reported to be new in literature. The enthalpies of formation for atomization and ionization of the neutral GeX2 dihalides are also reported here. The enthalpies of ionization are reported first time in literature and found consistent with other group IV dihalides. The reported molecular properties may be helpful to understand the chemistry involved in the plasma-assisted fabrication process of the Ge-based modern microelectronic devices, as well as will serve as a future reference. [ABSTRACT FROM AUTHOR]

Quantum chemistry calculations were performed to compare the reactivity indexes obtained within the conceptual density functional theory of phenolic and allyl-phenolic molecules and investigated in order to elucidate their antioxidant activity. Selected molecules share allyl and OH phenolic moieties, which can donate hydrogen atoms to highly reactive oxidant species. As a result, they inhibit or decrease the oxidative cycle. The calculation of bond dissociation energy relates this capability, together with reactivity indexes of the radicals produced, in order to measure and compare their stability. These indexes indicate a clear difference between these sets of structures with higher stability manifested by the allyl-phenolic-produced radicals. [ABSTRACT FROM AUTHOR]

The MP2 and CCSD calculations of the geometries and binding energies of the Li+·(N2)n (n = 1-4) complexes are obtained. The potential energy surface showed that these complexes exhibit one minimum state and one transition state. The mono- and di-ligated complexes exhibit linear configurations with a binding energy of 11.1 and 21.2 kcal mol−1, respectively. Trigonal planar and tetrahedral configurations are obtained for tri- and tetra-ligated complexes, respectively. The computed sequential bond dissociation energies (BDEs) of Li+·(N2)n (n = 1-4) complexes are also calculated in which the mono-ligated complex has the largest BDE value. The obtained trend is mainly dependent on the variation in the ion-quadrupole interaction of these ion complexes. These calculations predict that these complexes are of purely electrostatic nature. [ABSTRACT FROM AUTHOR]

Ab initio and density functional theory (DFT) calculations are employed to investigate the formation and isomerization pathways of methyl thionitrate, CHSNO, and the S-N bond dissociation energies (BDE) of the sulfonated methyl thionitrates of the type CHS(O)NO ( n = 0, 1, 2). The calculations indicate that CHSNO may be formed as a stabilized by-product in the reaction CHS + NO which mainly leads to CHSO + NO. In general, the compounds of the type CHS(O)NO ( n = 0, 1, 2) may be formed as bound intermediates in the homologous reactions CHS(O) + NO. The calculated S-N BDE exhibit an interesting dependence on the number of the sulfonic oxygen atoms present in each species. [ABSTRACT FROM AUTHOR]

Density functional theory calculations at the B3LYP/6-31G** theoretical level were performed for two series of guanidine-fused bicyclic skeleton derivatives (B-B7 and C-C7). The heats of formation (HOFs) were calculated via isodesmic reaction; the detonation properties were evaluated using the Kamlet-Jacobs equations; the bond dissociation energies were also analyzed to investigate the thermal stability of the cyclic nitramines. The results show that all the derivatives have high positive HOFs; compounds containing -N groupshave the highest HOFs, while compounds containing -NF groups have the highest density and detonation properties. Taking both of the detonation properties and thermal stabilities into consideration, compounds B1, B2, B5, C3, and C5 can be considered as the potential candidate of high-energy density compounds. [ABSTRACT FROM AUTHOR]

The mechanism, kinetics, and thermochemistry of the gas-phase reactions of CFClC(O)OCHCH,ethyl chlorodifluoroacetate (ECDFA) with the OH radical and Cl atom are investigated. Geometry optimization and frequency calculations have been performed at the MPWB1K/6-31+G(d,p) level of theory and energetic information is refined by using G2(MP2) theory. Transition states are searched on the potential energy surface of reaction channels and each of the transition states is characterized by the presence of only one imaginary frequency. Connections of the transition states between designated local minima are confirmed by intrinsic reaction coordinate calculation. Theoretically calculated rate constants at 298 K using the Canonical Transition State Theory are found to be in good agreement with the experimentally measured ones. Using group-balanced isodesmic reactions as working chemical reactions, the standard enthalpies of formation for CFClC(O)OCHCH, CFClC(O)OCHCH, and CFC(O)OCHCH are also reported for the first time. The hydrogen abstraction occurs mainly from -CH group. The T1 diagnostic calculation suggests that the multi-reference character is not an issue for such systems. The estimated atmospheric life time of ECDFA is expected to be around 24 days. [ABSTRACT FROM AUTHOR]

The characters of high density and high heat of formation of cage molecules have attracted a lot of investigations as potential energetic materials. Several such compounds have been synthesized, e.g., octanitrocubane, hexanitrohexaazaisowurzitane (CL-20), and 4-trinitroethyl-2, 6, 8, 10, 12-pentanitrohexaazaisowurtzitane(TNE-CL-20). In the present study, a new cage compound, namely 2, 4, 6, 8, 10, 12, 13-heptaazatetracyclo [5.5.1.0 3,11.0 5,9] tridecane (HATT), was proposed. Density functional theory has been employed to study the geometric and electronic structures for a series of nitro derivatives of HATT at the B3LYP/6-31G(d,p) level. Thermodynamic properties derived on the basis of statistical thermodynamic principles are linearly correlated with the numbers of nitro group as well as the temperature. Detonation performance was evaluated based on the calculated densities and heats of formation. It is found that some title compounds have high densities of ca. 1.9 g cm −3, detonation velocities over 9.0 km s −1, and detonation pressures of about 40.0 GPa and may be novel potential candidates of high energy density compounds (HEDCs). Thermal stability and pyrolysis mechanism of the nitro HATTs were investigated by calculating the bond dissociation energies ( BDE). In conjunction with the detonation performance and thermal stability, HATTs with no less than five nitro groups are recommended as the preferred candidates of HEDCs. These results provide basic information for the further studies of cage compounds. [ABSTRACT FROM AUTHOR]

Density functional theory method was used to study the heats of formation (HOFs), electronic structure, energetic properties, and pyrolysis mechanism of a series of trinitromethyl-substituted heterocycle (including triazole, tetrazole, furazan, tetrazine, and fused heterocycles) derivatives. It is found that the fused ring, tetrazine, and tetrazole are effective structural units for increasing the HOFs of the derivatives. The substitution of the combination of nitro and trinitromethyl is very useful for improving their HOFs. The calculated energetic properties indicate that the combination of the nitro and trinitromethyl is very helpful for improving their detonation properties and oxygen balances (OB). Most of the title compounds have a good OB over zero. The OB of six compounds are very high and over 22. An analysis of the bond dissociation energies for several relatively weak bonds suggests that the N-O bond in the ring is a trigger bond for BIII-1, CI-3, and CI-4, and the ring-NO and (NO)C-NO bond cleavage is likely to happen in thermal decomposition for the remaining compounds. Considering the detonation performance and thermal stability, seven compounds could be regarded as potential candidates for high-energy compounds. Four compounds may be used as the novel high-energy oxidizers. [ABSTRACT FROM AUTHOR]

The B3LYP/6-31G** method was used to investigate IR and Raman spectra, heat of formation, and thermodynamic properties of a new designed polynitro cage compound 1,3,5,7,9,11-hexanitrotetradecahydro-1 H-1,3,4,5,7,7b,9,11,12a,12b,12b,13-dodecaaza-4,8,12-(epimethanetriyl)cyclohepta[ l]cyclopenta[ def]phenanthrene. The detonation and pressure were evaluated using the Kamlet-Jacobs equations based on the theoretical density and HOFs. The bond dissociation energies and bond orders for the weakest bonds were analyzed to investigate the thermal stability of the title compound. The results show that N-NO bond is predicted to be the trigger bond during pyrolysis. There exists an essentially linear relationship between the WBIs of N-NO bonds and the charges - $$ Q_{{{\text{NO}}_{ 2} }} $$ on the nitro groups. The crystal structure obtained by molecular mechanics belongs to the P2 space group, with lattice parameters Z = 2, a = 11.4658 Å, b = 15.2442 Å, c = 10.2451 Å, ρ = 2.07 g cm. The designed compound has high thermal stability and good detonation properties and is a promising high-energy density compound. [ABSTRACT FROM AUTHOR]

Density functional theory method was used to study the heats of formation (HOFs), electronic structure, energetic properties, and thermal stability for a series of 1,2,3,4-tetrazine-1,3-dioxide derivatives with different substituents and bridge groups. It is found that the groups -NO, -C(NO), and -N=N- play a very important role in increasing the HOFs of the derivatives. The effects of the substituents on the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels and HOMO-LUMO gaps are coupled to those of different substituents and bridges. The calculated detonation velocities and pressures indicate that the group -NO, -NF, -ONO, -C(NO), or -NH- is an effective structural unit for enhancing the detonation performance for the derivatives. An analysis of the bond dissociation energies for several relatively weak bonds indicates that incorporating the groups -NO, -NF, -ONO, -C(NO), and -N=N- into parent ring decreases their thermal stability. Considering the detonation performance and thermal stability, 18 compounds may be considered as the target compounds holding the greatest potential for synthesis and use as high-energy density compounds. Among them, the oxygen balances of four compounds are equal to zero. These results provide basic information for the molecular design of the novel high-energy compounds. [ABSTRACT FROM AUTHOR]

A novel polynitro cage compound 10-(5-nitrimino-1,2,3,4-tetrazol-1-yl)methyl-2,4,6,8,12-pentanitro-hexaazaisowurtzitane, composed of CL-20 and tetrazole framework, has been designed. DFT-B3LYP/6-31G(d) and molecular mechanics methods are employed to calculate its IR spectrum, heat of formation, thermodynamic properties, and crystal structure. Besides, the stability of this compound is evaluated using the bond dissociation energy. The result shows that the initial step of thermal decomposition is the rupture of N-NO bond in the side chain. This compound is most likely to crystallize in the P-1 space group, and corresponding cell parameters are Z = 2, a = 7.65 Å, b = 14.30 Å, c = 10.36 Å, α = 91.53°, β = 50.83°, γ = 89.44°, and ρ = 2.025 g cm. Detonation velocity and detonation pressure of this compound are estimated to be 9.090 km s and 38.078 GPa using the Kamlet-Jacobs equation, similar to those of CL-20. Considering detonation performance and thermal stability, this compound meets the requirements of exploitable high energy density materials. [ABSTRACT FROM AUTHOR]

The molecular structure, heats of formation, energetic properties, strain energy and thermal stability for a series of substituted difurazano[3,4- b:3′,4′- e]piperazines and their analogues were studied using density functional theory. The results show that it is a useful way to increase the heat of formation values of energetic compounds by incorporating a five- or six-membered aromatic heterocycle to construct a fused ring system. The calculated detonation properties reveal that introducing one heterocycle to construct a fused ring structure greatly enhances their detonation properties. The substitution of the -NF, -NO or -NHNO group is very useful for enhancing the detonation performance for the substituted derivatives. According to molecular structure and natural bond orbital analysis, the introduction of the -NO, -NF or -NHNO group decreases the stability of the substituted derivative. There is a weak N-NO bond conjugation in the NO-substituted derivatives. An analysis of the bond dissociation energies for several relatively weak bonds suggests that all the unsubstituted derivatives have good thermal stability, but the substitution of -NO or -NF remarkably decreases their stability. Considering the detonation performance and thermal stability, eight compounds may be considered as the potential candidates of high-energy density materials with less sensitivity. [ABSTRACT FROM AUTHOR]

The B3LYP/6-31G(d) method of density functional theory was used to study molecular geometry, electronic structure, infrared spectrum, and thermodynamic properties. Detonation properties were evaluated using Kamlet-Jacobs equations based on the calculated density and heat of formation. Thermal stability of 3,5,7,10,12,14,15,16-octanitro-3,5,7,10,12,14,15,16-octaaza-pentacyclo[7.5.1.1.0.0]hexadecane (cage-HMX) was investigated by calculating the bond dissociation energy at unrestricted B3LYP/6-31G(d) level. The calculated results show that the first step of pyrolysis is the rupture of the N-NO bond. The crystal structure obtained by molecular mechanics belongs to P2 space group, with lattice parameters a = 8.866 Å, b = 11.527 Å, c = 13.011 Å, Z = 4, and ρ = 2.219 g cm. Both the detonation velocity of 9.79 km s and the detonation pressure of 45.45 GPa are better than those of CL-20. According to the quantitative standard of energetics and stability as a high-energy-density compound, cage-HMX essentially satisfies this requirement. These results provide basic information for molecular design of novel HEDCs. [ABSTRACT FROM AUTHOR]

Density functional theory has been used to investigate geometries, heats of formation (HOFs), C-NO bond dissociation energies (BDEs), and relative energetic properties of nitro derivatives of azole substituted furan. HOFs for a series of molecules were calculated by using density functional theory (DFT) and Møller-Plesset (MP2) methods. The density is predicted using crystal packing calculations; all the designed compounds show density above 1.71 g/cm. The calculated detonation velocities and detonation pressures indicate that the nitro group is very helpful for enhancing the detonation performance for the designed compounds. Thermal stabilities have been evaluated from the bond dissociation energies. Charge on the nitro group was used to assess the impact sensitivity in this study. According to the results of the calculations, tri- and tetra-nitro substituted derivatives reveal high performance with better thermal stability. [ABSTRACT FROM AUTHOR]

Based on the full optimized molecular geometric structures at B3LYP/6-31G**, B3LYP/6-31+G**, B3P86/6-31G**, and B3P86/6-31+G** levels, the densities (ρ), detonation velocities ( D), and pressures ( P) for a series of toluene derivatives, as well as their thermal stabilities, were investigated to look for high energy density compounds (HEDCs). The heats of formation (HOFs) are also calculated via designed isodesmic reactions. The calculations on the bond dissociation energies (BDEs) indicate that the BDEs of the initial scission step are between 48 and 59 kcal/mol, and pentanitrotoluene is the most reactive compound, while 2,4,6-trinitrotoluene is the least reactive compound for toluene derivatives studied. A good linear relationship between BDE/ E and impact sensitivity is also obtained. The condensed phase HOFs are calculated for the title compounds. These results would provide basic information for the further studies of HEDCs. The detonation data of pentanitrotoluene show that it meets the requirement for HEDCs. [ABSTRACT FROM AUTHOR]

The tetrazole is an important functionality of the most of energetic materials due to 80% nitrogen content, stability, and high enthalpy of formation. The present structure-property relationship study focuses on the optimized geometries of tetrazole derivatives obtained from density functional theory (DFT) calculations at B3LYP/6-31G* levels. The heat of formation (HOF) of tetrazole derivatives have been calculated by designing the appropriate isodesmic reactions. The increase in nitro groups on azole rings shows the remarkable increase in HOF. Density has been predicted by using CVFF force field. Increase in the nitro group increases the density. Detonation properties of the designed compounds were evaluated by using the Kamlet-Jacobs equation based on predicted densities and HOFs. Designed tetrazole derivatives show detonation velocity ( D) over 8 km/s and detonation pressure ( P) of about 32 GPa. Thermal stability was evaluated via bond dissociation energies (BDE) of the weakest C-NO bond at B3LYP/6-31G* level. Charge on the nitro group has been used to assess the sensitivity correlation. Overall, the study implies that designed compounds of this series are found to be stable and expected to be the novel candidates of high energy materials (HEMs). [ABSTRACT FROM AUTHOR]

Based on the full-optimized molecular geometric structures at B3LYP/6-31G* and B3P86/6-31G* levels, the densities (ρ), detonation velocities ( D), and pressures ( P) for a series of 1,2,3-triazole derivatives, as well as their thermal stabilities, were investigated to look for high energy density compounds (HEDCs). The heats of formation (HOFs) are also calculated via designed isodesmic reactions. The calculations on the bond dissociation energies (BDEs) indicate that the BDEs of the initial scission step are between 53 and 70 kcal/mol, and 4-nitro-1,2,3-triazole is the most reactive compound, while 1-(2′,4′-dinitrophenyl)-5-nitro-1,2,3-triazole is the least reactive compound for 1,2,3-triazole derivatives studied. The condensed phase heats of formation are also calculated for the title compounds. These results would provide basic information for the further studies of HEDCs. The detonation data of 1-(3′,4′-dinitrophenyl)-4-nitro-1,2,3-triazole and 1-(2′,4′-dinitrophenyl)-4-nitro-1,2,3-triazole show that they meet the requirement for HEDCs. [ABSTRACT FROM AUTHOR]

In this article, density functional theory has been utilized to study on the correlation between impact sensitivities h and the bond dissociation energies (BDEs) of nine triazole energetic explosives. By employing B3LYP and B3P86 method with the 6-311G** basis set, all the molecules have been fully optimized. The BDEs for removal of the NO group in these compounds have also been calculated at the same level. Computed results show that BDEs calculated by B3LYP method are all less than those by B3P86 method. The relationship between the impact sensitivities and the weakest C-NO bond dissociation energy (BDE) values have been investigated. The results indicate a good linear correlation between the impact sensitivity h and the ratio (BDE/ E) of the weakest BDE to the total energy E. [ABSTRACT FROM AUTHOR]