Chelate Coordination Compounds as a New Class of High-Energy Materials: The Case of Nitro-Bis(Acetylacetonato) Complexes

Abstract

The existence of areas of strongly positive electrostatic potential in the central regions of the molecular surface of high-energy molecules is a strong indicator that these compounds are very sensitive towards detonation. Development of high-energy compounds with reduced sensitivity towards detonation and high efficiency is hard to achieve since the energetic molecules with high performance are usually very sensitive. Here we used Density Functional Theory (DFT) calculations to study a series of bis(acetylacetonato) and nitro-bis(acetylacetonato) complexes and to elucidate their potential application as energy compounds with moderate sensitivities. We calculated electrostatic potential maps for these molecules and analyzed values of positive potential in the central portions of molecular surfaces in the context of their sensitivity towards detonation. Results of the analysis of the electrostatic potential demonstrated that nitro-bis(acetylacetonato) complexes of Cu and Zn have similar values of electrostatic potential in the central regions (25.25 and 25.06 kcal/mol, respectively) as conventional explosives like TNT (23.76 kcal/mol). Results of analysis of electrostatic potentials and bond dissociation energies for the C-NO2 bond indicate that nitro-bis(acetylacetonato) complexes could be used as potential energetic compounds with satisfactory sensitivity and performance.

Tris(3-nitropentane-2,4-dionato-κ2 O,O′) Complexes as a New Type of Highly Energetic Materials: Theoretical and Experimental Considerations

“…Analysis of electrostatic potential maps of the nitro-bis(acetylacetonato) complex of copper (Cu(AcAc-NO 2 ) 2 complex) showed that the value of the positive potential in the central regions of this complex (25.25 kcal/mol) is similar to the value of the electrostatic potential in the central regions of classical explosives like 2,4,6-trinitrotoluene-TNT (23.76 kcal/mol). Also, the calculated BDE value for the C-NO 2 bond of the Cu(AcAc-NO 2 ) 2 complex (59.50 kcal/mol) is very similar to the BDE value calculated for the C-NO 2 bond of the 2,4,6-trinitrotoluene (58.90 kcal/mol) [19,22]. However, the Cu(AcAc-NO 2 ) 2 complex forms coordination polymers in which monomer units are linked through nitro-groups, and this type of structure may prevent the dissociation of C-NO 2 bonds [32].…”

“…All geometry optimizations, vibrational frequency calculations, wave function file calculations, and BDE calculations were performed using the Gaussian09 program package [38]. Geometry optimizations, vibrational frequency calculations, and electrostatic potential map calculations were performed using the M06 functional and cc-PVDZ basis sets since this level of theory showed satisfactory results when applied to similar systems [22]. BDE values were calculated using the B3LYP/6-311++G** level of theory, following the previously proposed methodology [19].…”

“…Another approach for the design of HEM molecules with desired properties is the introduction of additional structural features in the HEM molecule that may provide new tools for the modification of the highly energetic properties of these compounds. A good example in this respect represents the class of high-energy transition metal complexes [2,[20][21][22][23][24][25][26][27][28][29]. Examples of simple Werner-type transition metal complexes that can act as explosives when exposed to adequate external stimuli have been known for more than 50 years [26].…”

“…Our recent Density Functional Theory study showed that nitro-bis(acetylacetonato) complexes may act as high-energy molecules with moderate sensitivity toward detonation [22]. In this study, two important indicators of the sensitivity of HEMs were analyzed: positive values of electrostatic potential and Bond Dissociation Energies of the weakest chemical bond in the molecule (the C-NO 2 bond).…”

How Do Small Differences in Geometries Affect Electrostatic Potentials of High-Energy Molecules? Critical News from Critical Points

“…Based on the calculated wave function files, electrostatic potential maps were calculated and visualized using Wave Function Analysis-Surface Analysis Suite (WFA-SAS) software [24]. Electrostatic potential maps were calculated at the M06/cc-pVDZ level of theory since this level of theory was successfully used for similar calculations in previous studies [16,25]. Critical points in electrostatic potential maps, and not in electron density were considered for the analysis.…”