scholarly journals Homolytic C-NO2 Bond Cleavage in Diaminodinitroethylene Isomers - A DFT Treatment

Author(s):  
Lemi Türker

Diaminodinitroethylene (DADNE) has three isomers including the well known geminal isomer, FOX-7. In the present study, the homolytic cleavage of one of the C-NO2 bonds of these isomers has been considered within the constraints of density functional theory at the level of UB3LYP/6-311++G(d,p). Transition states for that type of bond rupture are obtained. Various quantum chemical properties of the parent compounds and the decomposed systems are obtained, compared and discussed. Also the activation energies are calculated. The transition state originating from cis DADNE and the one from the geminal DADNE are found to be the most and least stable ones, respectively among the all.

Author(s):  
Lemi Türker

1,3,5-Triamino-2,4,6-trinitrobenzene, known as TATB, is an insensitive energetic material. On the other hand, certain metals like Al, Mg etc., are often involved in formulation of certain ammunition to increase the heat output of the composite. In the present study, the interaction of TATB and magnesium is considered in TATB+Mg and TATB+2Mg composites within the constraints of density functional theory at the level of B3LYP/6-311++G(d,p). The magnesium component disturbs TATB molecule mainly conformationally without causing any bond rupture. The composite formation is favorable, exothermic and they are electronically stable. As the magnesium content increases, the composites become more sensitive to impulse stimulus. Certain physicochemical, quantum chemical and spectral data are collected and discussed.


Author(s):  
Lemi Türker

Interaction of 1,1-diamino-2,2-dinitroethylene with nAl+mGa (n,m:1,2) admixture has been investigated within the constraints of density functional theory at the level of UB3LYP/6-311++G(d,p). Various multiplicity states arise for the composites due to the open-shell ground state electronic configurations of Al and Ga atoms. The composites are electronically stable, thermodynamically exothermic and have favorable Gibbs’ free energy of formation values. Various quantum chemical properties have been obtained and discussed. The calculated UV-VIS spectra indicate that some of the composites are infrared absorbing systems beyond 700 nm.


Author(s):  
Lemi Türker

Diaminodinitroethylene (DADNE) has three constitutional isomers; cis, trans and geminal. In the present study, epoxides of these isomers are considered within the restrictions of density functional theory at the level of UB3LYP/6-31G(d,p). Certain geometrical and quantum chemical properties of them are computed. The homolytic dissociation energy for C-NO2 bond in each case has been calculated at the level of UB3LYP/6-311++G(d,p). Based on the calculations performed, certain predictions are made for the impact sensitivities and specific impulse values of these epoxide derivatives of DADNE isomers.


Author(s):  
Lemi Türker

1,3,5-triamino-2,4,6-trinitrobenzene known as TATB is an insensitive high energy density material. It has two more constitutional isomers. The present study deals with all these triaminotrinitrobenzene isomers within the constraints of density functional theory at the levels of RB3LYP/6-31G(d,p) and UB3LYP/6-31G(d). Some geometrical and quantum chemical properties have been obtained and compared. The calculated IR and UV-VIS spectra are produced. Additionally the NICS values have been collected by calculating absolute NMR shielding values at the ring centers, NICS(0), and aromaticity of these isomers are compared. UB3LYP/6-31+G(d) level of calculations revealed that monoionic forms of these isomeric compounds are stable.


Author(s):  
Lemi Türker

1,3,3-Trinitroazetedine (TNAZ) is a powerful but insensitive energetic compound having C-NO2 and N-NO2 groups attached to a four-membered backbone. Aluminum powders are often added to explosives in order to have enhanced blast effect, etc. In the present study, aluminized TNAZ system is modeled for 1-3 Al atom(s) per TNAZ molecule within the restriction of density functional theory at the levels of UB3LYP/6-311++G(d,p) and UB3LYP/cc-PVDZ. Certain structural, physical and quantum chemical properties are obtained and discussed. The considered properties are found to be highly dependent on the multiplicity (thus the number of Al atoms present) of the composite systems considered. Also, calculated IR and UV-VIS spectra of the composites have been presented.


Author(s):  
Lemi Türker

Flindersine is a natural product of plant kingdom. Its structure contains a lactam group which could undergo 1,3-type proton tautomerism. It also has an embedded pyran moiety which might show valence tautomerism. Presently, those tautomers are investigated within the restrictions of density functional theory at the level of B3LYP/6-311++G(d,p). Certain quantum chemical output has been collected compared and discussed. Also the possibility of valence tautomerism has been searched by proposing two transition state paths.


Author(s):  
Lemi Türker

Various metal components like Al, B, Zr etc., as energetic particles are employed in thermobaric explosives. In composite systems compatibility of ingredients with each other is an important point to be considered. In the present study, effect of zinc on TEX, which is a caged explosive of nitramine type is investigated within the constraints of density functional theory at the levels of B3LYP/6-31+G(d), ωB97X-D/6-31G(d) and ωB97X-D/6-31+G(d). Various quantum chemical properties have been calculated for the TEX+Zn composite and compared with TEX. The zinc atom interacts with TEX molecule via destructive reduction of the explosive. The B3LYP/6-31+G(d) level of calculation predicts cleavage of one of the etheric bond of the cage as well as N-NO2 bond. Whereas, ωB97X-D/6-31G(d) and ωB97X-D/6-31+G(d) level of treatments show cleavage of only one of the N-NO2 bonds. In all the cases the zinc atom acquires some positive charge development.


Author(s):  
Lemi Türker

Pindone is a rodenticide having three keto groups in its structure. Presently, 1,3-type keto-enol tautomerism of pindone has been studied within the constraints of density functional theory at the level of B3LYP/6-311++G(d,p). Various structural and quantum chemical properties of these tautomers have been obtained, compared and discussed. Endocyclic and exocyclic enol forms of pindone are accompanied by dipole moment vectors having opposite directions. The endocyclic enol structure is found to be more stable than the exocyclic enol and pindone. IR and UV-VIS spectra are obtained. NICS(0) values are calculated to visualize the effect of tautomerism on the local aromaticity of the structures considered.


2016 ◽  
Vol 39 (3-4) ◽  
Author(s):  
Sandeep Pokharia ◽  
Rachana Joshi ◽  
Mamta Pokharia ◽  
Swatantra Kumar Yadav ◽  
Hirdyesh Mishra

AbstractThe quantum-chemical calculations based on density functional theory (DFT) have been performed on the diphenyltin(IV) derivative of glycyl-phenylalanine (H


Author(s):  
Vladimir Tsirelson ◽  
Adam Stash

This work extends the orbital-free density functional theory to the field of quantum crystallography. The total electronic energy is decomposed into electrostatic, exchange, Weizsacker and Pauli components on the basis of physically grounded arguments. Then, the one-electron Euler equation is re-written through corresponding potentials, which have clear physical and chemical meaning. Partial electron densities related with these potentials by the Poisson equation are also defined. All these functions were analyzed from viewpoint of their physical content and limits of applicability. Then, they were expressed in terms of experimental electron density and its derivatives using the orbital-free density functional theory approximations, and applied to the study of chemical bonding in a heteromolecular crystal of ammonium hydrooxalate oxalic acid dihydrate. It is demonstrated that this approach allows the electron density to be decomposed into physically meaningful components associated with electrostatics, exchange, and spin-independent wave properties of electrons or with their combinations in a crystal. Therefore, the bonding information about a crystal that was previously unavailable for X-ray diffraction analysis can be now obtained.


Sign in / Sign up

Export Citation Format

Share Document