Nitrogen-Rich Salts of 1-Methyl-5-nitriminotetrazolate: An Auspicious Class of Thermally Stable Energetic Materials

Abstract

1-Methyl-5-nitriminotetrazole (1) was formed by nitration of 1-methyl-5-aminotetrazole, which was obtained by methylation of sodium 5-aminotetrazolate. 1 was deprotonated using potassium hydroxide forming the corresponding potassium salt (2), which was transformed into silver 1-methyl-5-nitriminotetrazolate (3) by the reaction with silver nitrate. Guanidinium (4), 1-aminoguanidinium (5), 1,3-diaminoguanidinium (6), 1,3,5-triaminoguanidinium (7), and azidoformamidinium (8) 1-methyl-5-nitriminotetrazolate were prepared by metathesis reactions either using 2 and guanidinium perchlorates or 3 and guanidinium chlorides under the precipitation of KClO4 or AgCl, respectively. All compounds were fully characterized by single crystal X-ray diffraction, vibrational spectroscopy, multinuclear NMR spectroscopy, elemental analysis, differential scanning calorimetry (DSC) as well as bomb calorimetry. Since the packing of molecules in the solid state influences the properties of materials significantly, a detailed description of the crystal structures of 3, 4, 6, 7, and 8 is given. Using the heats of combustion the heats of formations were calculated to be strongly endothermic. Several detonation parameters like the detonation pressure and detonation velocity were calculated using the EXPLO5 software. In addition the sensitivities were tested using the BAM drop hammer and friction tester. With respect to developing new high explosives triaminoguanidinium 1-methyl-5-nitriminotetrazolate shows the most promising values and was therefore successfully tested in a Koenen Test (critical diameter ≤ 10 mm)