Dense Hydrogen-Bonded Assembly of Hydrogen-Rich Cations and Pentazolate Anions: A Series of Highly Insensitive Ionic Salts

Compounds containing the pentazolate anion (<i>cyclo</i>-N₅^-) represent a distinctive group of energetic materials that have received extensive attention in recent years. <i>Cyclo</i>-N₅^- was used as a polynitrogen anion for the syntheses of energetic salts through metathesis reactions. Propamidinium (<b>1</b>), 5-amino-4-carbamoyl-1<i>H</i>-imidazol-3-ium (<b>2</b>), (1<i>H</i>-1,2,3-triazol-4-yl)methanaminium (<b>3</b>), 5-amino-4<i>H</i>-1,2,4-triazol-1-ium (<b>4</b>), 5-amino-3-methyl-4<i>H</i>-1,2,4-triazol-1-ium (<b>5</b>), and amino(pyrimidin-2-yl)methaniminium (<b>6</b>) pentazolates were obtained with high yields (>80%), and their crystal structures were confirmed through single-crystal X-ray diffraction analyses. Hirshfeld surface analyses and 2D fingerprint plots generated by CrystalExplorer17 demonstrated that these compounds exhibited extensive hydrogen-bonding networks in their crystal packing. Mechanical sensitivity tests showed that all the prepared salts were highly insensitive (IS > 35 J, FS > 360 N), providing valuable insights for the further exploration of broader energetic materials containing <i>cyclo</i>-N₅^-.