Lone pair/π-hole interactions in the edge-to-face stacking of the criss-cross construction molecule: Towards thermally stability, low sensitivity, and high detonation performance

Abstract

4-Azasydnone-3,5-dinitropyrazole was synthesized and fully characterized by IR, multinuclear NMR spectroscopy, elemental analysis and differential scanning calorimetry (DSC). Its crystal structure was determined by single-crystal X-ray diffraction and packing characteristics were thoroughly studied by non-covalent interaction (NCI) and Hirshfeld surface analysis. The theoretical detonation pressure (P) and velocity (vD) were also calculated (Gaussian 09 and EXPLO5). Attributing to the lone pair/π-hole interactions in its dense edge-to-face packing structure, DNPA shows a high density (1.86 g cm−3), good thermal stability (Td = 229 °C), excellent detonation performance (vD = 8703 m s−1, P = 32.7 GPa) and acceptable sensitivities (IS = 17 J, FS = 230 N), and is deservedly superior to 1,3,5-trinitro-1,3,5-triazinane (RDX). These advantages highlight the potential use of DNPA as high-energy–density materials.