Probing the weakest bond and the cleavage ofp‐chlorobenzaldehyde diperoxide energetic molecule via quantum chemical calculations and theoretical charge density analysis

Abstract

ABSTRACT:A high-level ab initio Hartree-Fock/Møller-Plesset 2 and density functional theory quantum chemical calculations were performed on p-chlorobenzaldehyde diperoxide energetic molecule to understand its bond topological, electrostatic, and energetic properties. The optimized molecular geometry for the basis set 6-311G** exhibit chair diperoxide ring and planar aromatic side rings. Although the diperoxide ring bear same type of side rings, surprisingly, both the rings are almost perpendicular to each other, and the dihedral angle is 96.1 . The MP2 method predicts the OAO bond distance as $1.466 Å . The charge density calculation reveals that the CAC bonds of chlorobenzaldehyde ring have rich electron density and the value is $2.14 e Å À3. The maximum electron density of the OAO bonds does not lie along the internuclear axes; in view of this, a feeble density is noticed in the ring plane. The high negative values of laplacian of CAC bonds (approximately À22.4 e Å À5) indicate the solidarity of these bonds, whereas it is found too small (approximately À1.8 e Å À5 for MP2 calculation) in OAO bonds that shows the existence of high degree of bond charge depletion. The energy density in all the CAC bonds are found to be uniform. A high electronegative potential region is found at the diperoxide ring which is expected to be a nucleophilic attack area. Among the bonds, the OAO bond charge is highly depleted and it also has high bond kinetic energy density; in consequence of this, the molecular cleavage is expected to happen across these bonds when the material expose to any external stimuli such as heat or pressure treatment.

A theoretical charge density study on nitrogen-rich 4,4′,5,5′-tetranitro-2,2′-bi-1H-imidazole (TNBI) energetic molecule

“…This electrostatic information paves the way to predict the reaction surface of the molecule. These kinds of electronegative regions are found in the reported structures [5][6][7][8] (Fig. 6).…”

“…The IS of a material estimated from the h 50 method is a given weight falling upon the material gives a 50% probability of initiating an explosion. Smaller the magnitude of h 50 greater the sensitivity [5,6,44]. Here, we have examined the relationship between BDE/E and the IS of TNBI.…”

“…Here, we have examined the relationship between BDE/E and the IS of TNBI. The h 50 % equation [5,6,41,44] for the TNBI is…”

“…The sensitivity of an energetic material to external stimuli is also one of the key properties of energetic materials and its potential application is the handling safety [9,10]. Recent report says that, some extent, the sensitivity of the energetic materials is related to the bond topological and electrostatic properties of the material [5][6][7][8]. Hence, to understand the sensitivity of the energetic materials, it is essential to determine the relationship between the above properties of energetic material and their sensitivities for impact, shock, and heat.…”

“…The bond topological characterization of charge density analysis allows to understand the bond strength (strong and weak) of the molecule. Our recent studies on various energetic molecules explore the weakest bonds of the molecule from the bond topological characterization [5][6][7][8]. The sensitivity of an energetic material to external stimuli is also one of the key properties of energetic materials and its potential application is the handling safety [9,10].…”