Maximum Compaction of Ionic Organic Explosives: Bis(hydroxylammonium) 5,5′-Dinitromethyl-3,3′-bis(1,2,4-oxadiazolate) and its Derivatives

Within this contribution on bis(oxadiazoles) we report on bis-hydroxylammonium 5,5'-dinitro-methyl-3,3'-bis(1,2,4-oxadiazolate), which (to the best of our knowledge) shows the highest density (2.00 gcm(-3) at 92 K, 1.95 gcm(-3) at RT) ever reported for an ionic CHNO explosive. Also the corresponding bis(ammonium) salt shows an outstanding density of 1.95 gcm(-3) (173 K). The reaction of the 3,3'-bis(1,2,4-oxadiazolyl)-5,5'-bis(2,2'-dinitro)-diacetic acid diethyl ester with different nitrogen-rich bases, such as ammonia, hydrazine, hydroxylamine, and triaminoguanidine causes decarboxylation followed by the formation of the corresponding salts (cation/anion stoichiometry 2: 1). The reactions are performed at ambient temperature in H2O/MeOH mixtures and furnish qualitatively pure products showing characteristics of typical secondary explosives. The obtained compounds were characterized by multinuclear NMR spectroscopy, IR and Raman spectroscopy, as well as mass spectrometry. Single-crystal X-ray diffraction studies were performed and the structures of all compounds were determined at low temperatures. The thermal stability was measured by differential scanning calorimetry (DSC). The sensitivities were explored by using the BAM drophammer and friction test. The heats of formation were calculated by the atomization method based on CBS-4M enthalpies. With these values and the X-ray densities, several detonation parameters such as the detonation pressure, velocity, energy, and temperature were computed using the EXPLO5 code.