Improving the anti-hygroscopicity and safety of hydroxylamine pentazolate salt (NH3OH+N5−) by cocrystallization

Abstract

As a research hotspot in energetic materials, pentazolate salts have been restricted in widespread application due to their strong hygroscopicity and high sensitivity. In this study, a cocrystal of NH₃OH⁺N₅⁻ and 18-crown-6 (18C6) was prepared (1 : 1 molar ratio) via the solvent-evaporation method. It was characterized by single crystal X-ray diffraction, powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), and noncovalent interaction analysis. Crystal structure analysis shows that hydrogen bonds between NH₃OH⁺ cations and the 18C6 ring drive cocrystal formation. Non-covalent interaction analysis shows that in NH₃OH⁺N₅⁻ and the cocrystal, N–H⋯N (63.9%) and N–H⋯O (43.0%) hydrogen bonds account for a significant proportion of the weak interactions, respectively. The results confirm that cocrystal formation improves the anti-hygroscopicity and safety of the compound (IS = 25 J, FS = 192 N).