Nitrogen‐Rich 5,5′‐Bistetrazolates and their Potential Use in Propellant Systems: A Comprehensive Study

Abstract

A large variety of twice-deprotonated nitrogen-rich 5,5'-bistetrazolates, that is, the ammonium (1), hydrazinium (2), hydroxylammonium (3), guanidinium (4), aminoguanidinium (5), diaminoguanidinium (6), triaminoguanidinium (7), and diaminouronium (8) salts, have been synthesized. Energetic compounds 1-8 were fully characterized by single-crystal X-ray diffraction (except 8), NMR spectroscopy, IR and Raman spectroscopy, and differential scanning calorimetry (DSC) measurements. With respect to their potential use in propellant applications, the sensitivity towards impact, friction, and electrical discharge were determined. Several propulsion and detonation parameters (e.g., heat of explosion, detonation velocity) were computed by using the EXPLO5 computer code based on calculated (CBS-4M) heats of formation and X-ray densities. Additionally, the performance of 1-8 in various formulations was investigated by calculating the specific energy and specific impulse of the compounds under isochoric conditions.

Preparation and Crystal Structure of Diaqua(μ-5,5'-bistetrazolato-κ4N1,N2,N5,N6)copper(II)

“…However, this bond length is in agreement with the Cu-N bond of the similar bis(5-amino-1,2,4-triazol-3-yl)copper(II) complex [7]. The Cu1-N2 ii bond can be arranged as a normal coordinative bond but is with 2.27 Å still longer than the Cu1-O1, Cu1-O2, Cu1-N1 and Cu1-N6 [9]. However, the C-bridged tetrazole rings of the 5,5'-BT are twisted to each other (<(N1-C1-C2-N5) = 24.9°) due to sterical effects and the above mentioned weak bond between N5 and Cu1.…”

Pushing the limits of energetic materials – the synthesis and characterization of dihydroxylammonium 5,5′-bistetrazole-1,1′-diolate

“…† Its density of 1.918 g cm À3 is significantly higher than that of non oxide dihydroxyl ammonium 5,5 0 bistetrazolate (1.742 g cm À3 ) recently pub lished. 17 The reason for this may be the strong hydrogen bond network (involving all four hydrogen atoms of the hydroxyl ammonium cations) (Fig. 1).…”

Preparation, Crystal and Properties of Nitrogen-Rich Energetic Salt of Bis(semicarbazide) 5,5′-Bitetrazole-1,1′-diolate

“…The C-N bonds were 1.329 Å for N4-C1 and 1.342 Å for N1-C1, shorter than the normal C-N bond of 1.47 Å and longer than the normal C=N bond of 1.27 Å [19], while the C-C bond was 1.446 Å, which is in the normal range of 1.32 Å for the C=C bond and 1.53 Å for the C-C bond. The bond angles for the tetrazole ring of the BTO anion have a max of 129.89˝for N1-C1-O1 and 105.53˝for N3-N2-C1.…”

“…As shown in Table 2, in the BTO anion, the N-N bond lengths range from 1.315 Å for N2-N3 to 1.337 Å for N3-N4 with an average value of 1.329 Å, which was 0.125 Å shorter than the normal N-N bond length (1.454 Å) and 0.084 Å longer than the normal N=N bond (1.245 Å) [19]. The C-N bonds were 1.329 Å for N4-C1 and 1.342 Å for N1-C1, shorter than the normal C-N bond of 1.47 Å and longer than the normal C=N bond of 1.27 Å [19], while the C-C bond was 1.446 Å, which is in the normal range of 1.32 Å for the C=C bond and 1.53 Å for the C-C bond.…”