Simple, Nitrogen-Rich, Energetic Salts of 5-Nitrotetrazole

Abstract

A new family (ammonium, 1, hydrazinium, 2, guanidinium, 3, aminoguanidinium, 4, diamino-guanidinium, 5, and triaminoguanidinium, 6) of simple, nitrogen-rich energetic salts based on 5-nitro-2 H-tetrazole (HNT) were synthesized. In addition, the hemihydrate of 1 (1a) and the hydrate of 6 (6a) were also isolated. In all cases, stable salts were obtained and fully characterized by vibrational (IR, Raman) spectroscopy, multinuclear ((1)H, (13)C and (14)N) NMR spectroscopy, mass spectrometry, elemental analysis, and X-ray structure determination. Compounds 1and 2 crystallize in the monoclinic space group P2 1/c, 1a and 3 crystallize in C/2 c, 4 in P2 1/n, 5 in P2 1, 6 in orthorhombic P2 12 12 1, and 6a in triclinic P1. Initial safety testing (impact, friction, and electrostatic sensitivity) and thermal stability measurements (DSC) were also carried out. The NT salts all exhibit good thermal stabilities (decomposition above 150 degrees C). The constant volume energies of combustion (Delta c U(exp)) of 1-6 were experimentally determined by oxygen bomb calorimetry to be -1860(30) cal/g ( 1), -1770(30) cal/g ( 1a), -2110(150) cal/g (2), -2250(40) cal/g ( 3), -2470(30) cal/g (4), -2630(40) cal/g (5), -2690(50) cal/g (6), and -2520(50) cal/g (6a). Because of the significant experimental uncertainties obtained in these measurements, their validity was checked by way of quantum chemical calculation (MP2) of electronic energies and an approximation of lattice enthalpy. The predicted constant volume energies of combustion (Delta c U(pred)) calculated by this method were -2095.9 cal/g (1), -1975.7 cal/g ( 1a), -2362.4 cal/g (2), -2526.6 cal/g (3), -2654.6 cal/g (4), -2778.6 cal/g ( 5), -2924.0 cal/g (6), and -2741.4 cal/g ( 6a). From the experimentally determined density, chemical composition, and energies of formation (back calculated from the heats of combustion) the detonation pressures and velocities of 1 (7950 m/s, 23.9 GPa), 1a (7740 m/s, 22.5 GPa), 2(8750 m/s, 30.1 GPa), 3 (7500 m/s, 20.1 GPa) 4(8190 m/s, 24.7 GPa), 5(8230 m/s, 24.4 GPa), 6 (8480 m/s, 26.0 GPa) and 6a (7680 m/s, 20.7 GPa) were predicted using the EXPLO5 code.

Energetic Salts of the Binary 5‐Cyanotetrazolate Anion ([C2N5]−) with Nitrogen‐Rich Cations

“…The vibrations corresponding to the ammonium, hydrazinium, semicarbazidium, guanidinium, aminoguanidinium, and triaminoguanidinium cations in compounds 3-9 have been described previously, and therefore a detailed discussion is omitted from this work. [8,15] To establish a characteristic set of vibrations for the 5-cyanotetrazolate anion, its vibrational frequencies were calculated by quantum chemical methods (see Experimental Section for details of the method used). The quantum chemical calculations facilitated the assignment of the anion bands observed in the vibrational spectra of 1-9, and provided structural information about the 5-cyanotetrazolate anion in the gaseous state.…”

“…[8] The energies of formation of all the compounds were then back-calculated on the basis of the general combustion equations for CHNO compounds (see below for the combustion equations of salts 3-9), Hesss Law, the standard heats of formation for water and carbon dioxide, [28] and a correction for the change in the gas volume during combustion. The high nitrogen content of compounds 3-9 results in high positive heats of formation.…”

“…Both 1·1.5 H 2 O and 2 were used as starting materials for the synthesis of a new family of nitrogen-rich salts containing the 5-cyanotetrazolate anion and nitrogen-rich cations, namely ammonium (3), hydrazinium (4), semicarbazidium (5), guanidinium (6), aminoguanidinium (7), diaminoguanidinium (8), and triaminoguanidinium (9). Compounds 1-9 were synthesised in good yields and characterised by using analytical and spectroscopic methods.…”

“…[8] However, in comparison with B (anhydrous), alkali or transitionmetal salts of B have sensitivities comparable to commonly used primary explosives, and might have potential as more environmentally friendly alternatives to lead(II) azide in initiating devices. [9] In addition, a recent report from our group showed that both metal and nitrogen-rich salts of 5-azido-1H-tetrazole (C) are very powerful explosives.…”

“…Consequently, we wish to present our work on the preparation, characterisation, and energetic testing of the sodium (1) and potassium (2) salts of 5-cyanotetrazole, as well as those of the nitrogen-rich ammonium (3), hydrazinium (4), semicarbazidium (5). guanidinium (6), aminoguanidinium (7), diaminoguanidinium (8), and triaminoguanidinium (9) derivatives.…”