Energetics and Ionic–Electronic and Geometric Variabilities of Hydroxylammonium-Based Salts

Abstract

In the present work, we study the formation energy of energetic ionic salts (EISs), as well as the volumetric and electric variabilities of ions involved in EISs, by employing 25 hydroxylammonium cations (HA+) in 22 salts as examples. We identify the viability of a dispersion-corrected density functional theory method, PBE-D3(BJ), to describe the lattice parameters, with a mean relative deviation of 1.26% and a maximal relative deviation of 2.5%. Thereby, the ionization energy, formation energy, and lattice energy are predicted. The variability of volume (V HA+) is confirmed in different HA+-based salts, as well as between two HA+ of the same lattice with Z′ > 1. The largest difference of V HA+ among the 25 HA+ reaches ∼9%. This variability of V HA+ is originated from the difference in crystal field effects, or intermolecular interactions. That is, the stronger intermolecular hydrogen bond tends to exhibit a stronger drag and pull effect on HA+ and leads to a larger V HA+. In comparison, it exhibits a more significant variability of electricity, as the maximal total Mulliken charge of HA+ (Q HA+) is >1.67 times the minimal one. Moreover, the observed Q HA+ varying from 0.164 to 0.438 e is much less than the apparent charge of 1 e, suggesting the highly insufficient charge of HA+ in EISs. This means that the ionic bonding does not necessarily govern the intermolecular interactions in common EISs. Besides, an electrostatic potential (ESP) minimum-oxygen balance (OB) correlation is found in the anions countering HA+, as the more negative OB tends to cause a more negative ESP minimum. All of these findings are expected to richen the insight into the nature of EISs as a special group of EMs.

Crystal Packing of Planar Organic Azide Molecules

“…Previous study showed a rough positive correlation between the Coulomb force (Σ F i ) and n–π coupling energy, in which F i is positively dependent on the negative and positive ESP extremes, i.e., larger ESP extremes generally suggest stronger coupling energy . Moreover, a recent work confirmed a correlation of ESP extremes with the oxygen balance of organic energetic anions involved in 25 hydroxylammonium salts, as the higher OB generally leads to a higher negative ESP extreme . All of these suggest that the addition of oxazole is beneficial to enhance intermolecular interaction.…”

“…61 Moreover, a recent work confirmed a correlation of ESP extremes with the oxygen balance of organic energetic anions involved in 25 hydroxylammonium salts, as the higher OB generally leads to a higher negative ESP extreme. 62 All of these suggest that the addition of oxazole is beneficial to enhance intermolecular interaction. After all, it is more electronegative than N atoms, which are contained in −N 3 .…”

Fluorine‐Containing Functional Group‐Based Energetic Materials

“…The design and synthesis of high energy density materials (HEDMs) that exhibit high density, low sensitivity, and good energetic performance continues to attract significant research interest [1,2] . The major challenge in developing HEDMs is achieving balance between energy and stability [3–7] . Generally, a high energetic material exhibits poor stability.…”

“…[1,2] The major challenge in developing HEDMs is achieving balance between energy and stability. [3][4][5][6][7] Generally, a high energetic material exhibits poor stability. Among energetic materials, traditional explosives, such as 2-methyl-1,3,5trinitrobenzene (TNT), 2,4,6-triamine-1,3,5-trinitrobenzene (TATB), 1,3,5-trinitroperhydro-1,3,5-triazine (RDX), 1,3,5,7tetranitro-1,3,5,7-tetrazoctane (HMX), 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105), 2,2-dinitroethene-1,1-diamine (FOX-7) and 1,2-bis-(2,4,6-trinitrophenyl)-ethylene (HNS) have been used in industrial, mining, and military applications.…”