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Based on the full optimized molecular geometric structure at B3LYP/cc-pvtz method, the newly designed compound 4, 10-dinitro-2, 6,8, 12-tetraoxa-4, 10-diazatetracyclo[5.5.0.05, 903, 11]dodecane (TEX) was investigated. Additionally, the IR spectrum, the thermal stability, and the detonation performance were predicted. The obtained crystal structure of TEX belongs to Pbca space group and lattice parameters are Z = 8, a = 8.614 Å, b = 12.877 Å, c = 26.065 Å, ρ = 2.015 g ·cm-3. Calculation results show that TEX has better detonation properties than HMX and is a high energy density compound with better stability. [ABSTRACT FROM AUTHOR]

In the present work, theoretical study on the mechanism and kinetics of the gas-phase reactions of CFCFCHOCH (HFE-365mcf3) with the OH radicals have been performed using meta-hybrid modern density functional M06-2X in conjunction with 6-31+G(d,p) basis set. Reaction profiles for OH-initiated hydrogen abstraction are modeled including the formation of pre-reactive and post-reactive complexes at entrance and exit channels. Our calculations reveal that hydrogen abstraction from the -CH group is thermodynamically more facile than that from the -CH group. This is further ascertained by the calculated C-H bond dissociation energy of CFCFCHOCH molecule. The rate constants of the titled reactions are computed over the temperature range of 250-450 K. The calculated rate constant value at 298 K is found to be in reasonable agreement with the experimental results. The atmospheric life time of HFE-365mcf3 is estimated to be 42 days. The atmospheric fate of the alkoxy radicals, CFCFCH(O)OCH and CFCFCHOCHO are also investigated for the first time using the same level of theory. Out of three plausible decomposition channels, our results clearly point out that reaction with O is the dominant atmospheric sink for the decomposition of CFCFCH(O)OCH radical in the atmosphere. [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]

Theoretical investigation has been carried out on the kinetics and reaction mechanism of the gas-phase reaction of 3-hydroxy-2-butanone (3H2B) with OH radical using dual-level procedure employing the optimization at DFT(BHandHLYP)/6-311 ++G(d,p) followed by a single-point energy calculation at the CCSD(T)/6-311 ++G(d,p) level of theory. The pre- and post reactive complexes are also validated at entrance and exit channels, respectively. Thus reaction may be proceed via indirect mechanism. The intrinsic reaction coordinate (IRC) calculation has also been performed to confirm the smooth transition from a reactant to product through the respective transition states. The rate coefficients were calculated for the first time over a wide range of temperature (250-450 K) and described by the following expression: k = 7.56 × 10exp[ −(549.3 ± 11.2)/T] cm molecules. At 298 K, our calculated rate coefficient 1.20 × 10 cm molecule s is in good agreement with the experimental results. Our calculation indicates that H-abstraction from α-C-H site of 3H2B is the dominant reaction channel. Using group-balanced isodesmic reactions, the standard enthalpies of formation for 3H2B and radicals generated by hydrogen abstraction are reported for the first time. The branching ratios of the different reaction channels are also determined. Also, the atmospheric lifetime of 3H2B is also calculated to be 1.04 days. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Detailed theoretical investigation has been performed on the mechanism, kinetics and thermochemistry of the gas phase reactions of CF 3 CHFCF 2 OCF 3 with OH radicals and Cl atoms using M06-2X/6-31+G(d,p) level of theory. The energetic calculations were refined by using aug-cc-pVTZ basis set. Our calculations reveal that OH-initiated hydrogen abstraction is thermodynamically and kinetically more facile than that from the Cl-initiated hydrogen abstraction. Using group-balanced isodesmic reactions, the standard enthalpies of formation (Δ H f °) for species and bond dissociation energies for C H bond are also reported. The Δ H f ° for CF 3 CHFCF 2 OCF 3 and •CF(CF 3 )CF 2 OCF 3 species calculated from M06-2X/6-31+G(d,p) results are −523.15 and −471.65 kcal mol −1 , respectively. The rate constants evaluated by canonical transition state theory (CTST) are found to be 1.22 × 10 −15 and 3.40 × 10 −17 cm 3 molecule −1 s −1 which are in a reasonable agreement with the available experimental data of (1.43 ± 0.28) × 10 −15 and (4.09 ± 0.42) × 10 −17 cm 3 molecule −1 s −1 , respectively, for OH and Cl-initiated hydrogen abstraction reactions. The atmospheric life time of CF 3 CHFCF 2 OCF 3 is estimated to be 38.5 years. The atmospheric fate of the alkoxy radical, CF 3 CF(O•)CF 2 OCF 3 is also investigated for the first time using same level of theory. [ABSTRACT FROM AUTHOR]

An azo bridge (-N = N-) can not only desensitize explosives but also dramatically increase their heats of formation and explosive properties. Amino and nitro are two important high energy density functional groups. Here, we present calculations on 1-nitro-1-triazene (NH-N = N-NO). Thermal stability and detonation parameters were predicted theoretically at CCSD(T)/6-311G* level, based on the geometries optimized at MP2/6-311G* level. It was found that the p → π conjugation interaction and the intramolecular hydrogen bonding that exist in the system together increase the thermal stability of the molecule. Moreover, the detonation parameters were evaluated to be better than those of the famous HMX and RDX. Finally, the compound was demonstrated to be a high energy density material. [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]

Density functional theory studies on cyclic nitramines were performed at B3LYP/6-311G(d,p) level. The crystal structures were obtained by molecular packing calculations. Heats of formation (HOFs) were predicted through designed isodesmic reactions. Results indicate that the value of HOF relates to the number of =N-NO2 group and aza nitrogen atom and increases with the augment of the number of =N-NO2 group and aza nitrogen atom for cyclic nitramines. Detonation performance was evaluated by using the Kamlet-Jacobs equations based on the calculated densities and HOFs. All the cyclic nitramines exhibit better detonation performance than 1,3,5-trinitro-1,3,5-triazacyclohexane and 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane. The stability of cyclic nitramines was investigated by the bond dissociation energies. The result shows that the increase of =N−NO2 group or aza nitrogen atom reduces the stability of the title compounds. These results provide basic information for molecular design of novel high energetic density materials. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A Theoretical study on the mechanism of the reactions of CFClC(O)OCH with the OH radical and Cl atom is presented. Geometry optimization and frequency calculations have been performed at the MPWB1K/6-31+G(d,p) level of theory and energetic information is further refined by calculating the energy of the species using G2(MP2) theory. Transition states are searched on the potential energy surface involved during the reaction channels and each of the transition states are characterized by presence of only one imaginary frequency. The existence of transition states on the corresponding potential energy surface is ascertained by performing intrinsic reaction coordinate (IRC) calculation. Theoretically calculated rate constants at 298 K and atmospheric pressure using the canonical transition state theory (CTST) 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)OCH CFClC(O)OCH and CFC(O)OCH are also reported for the first time. [ABSTRACT FROM AUTHOR]

Density functional theory calculations at B3LYP/6-31G** and B3P86/6-31G** levels were performed to predict the densities ( ρ), detonation velocities (D), pressures (P) and the thermal stabilities for a series of 1,2,4-triazole derivatives for looking 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 position of the subsitutent group has great effect on the BDE and the BDEs of the initial scission step are between 31 and 65 kcal/mol. In addition, the condensed phase heats of formation are also calculated for the title compounds. These results would provide basic information for further studies of HEDCs. [Figure not available: see fulltext.] [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]

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]

Abstract: DFT calculations using MPWB1K method with COSMO continuum solvation model have been carried out to quantify the trans influence of various X ligands (E X) in [PtIICl3X]n− complexes as well as the mutual trans influence of two X and Y ligands (E XY) in [PtIICl2XY]n− complexes. A quantitative structure energy relationship (QSER) is derived for predicting the E XY using E X and E Y and this relationship showed a strong similarity to a QSER derived for predicting E XY of [PdIICl2XY]n− complexes. Quantification of the contributions of E X and E XY to the bond dissociation energy of the ligand X (BDE X) in complexes of the type [MIIX(Y)X′(Y′)] (M = Pd, Pt) is also achieved. The BDE X of any ligand X in these complexes can be predicted using the equations, viz. BDE X(Pd) = 1.196E X − 0.603E XY − 0.118E X’Y’ + 0.442D X + 15.169 for Pd(II) complexes and BDE X(Pt) = 1.420E X − 0.741E XY − 0.125E X’Y’ + 0.498D X + 13.852 for Pt(II) complexes, where D X corresponds to the bond dissociation energy of X in [MIICl3X]n− complexes. These expressions suggest that the mutual trans influence from X and Y is more dominant than the mutual trans influence from X′ and Y′ and both factors contribute significantly to the weakening of M–X bond. We also obtained a strong linear relationship between E X and the electron density ρ(r) at the bond critical point of M–Cl bond trans to the X in [MIICl3X]n− and this allows us to express the BDE X(Pd) and BDE X(Pt) in terms of only the ρ(r) and D X. We have demonstrated that using a database comprising of D X and the ρ(r), the bond dissociation energy of X in complexes of the type [MIIX(Y)X′(Y′)] can be predicted. [Copyright &y& Elsevier]

Abstract: The heats of formation (HOFs) were calculated for a series of neopentyl difluoroamino compounds by using density functional theory (DFT) method with 6-311G∗∗ basis set, as well as semi-empirical methods. In the isodesmic reactions designed for the computation of HOF, the neopentane was chosen as a reference compound. The HOFs increase smoothly as –ONO2 groups being replaced by –NF2 and –NO2. However, HOFs increase dramatically as –ONO2 groups being replaced by –N(NO2)CH3 and –N3 groups. The variations of HOFs are different with different substituents. The semi-empirical MO (MNDO, AM1, and PM3) methods did not produce accurate and reliable results for the HOFs of the title compounds. The relative stability of the title compounds was evaluated based on the calculated HOFs, the energy gaps between the frontier orbitals and the bond order of C–R bond (C–NF2, C–ONO2, C–NO2 and C–N3). The magnitudes of intramolecular group interactions were predicted through the disproportionation energies. Thermal stabilities were evaluated via bond dissociation energies (BDE) at the B3LYP/6-311G∗∗ level. These results provide basic information for the molecular design of novel high energetic density materials. [Copyright &y& Elsevier]