3,6,7‐Triamino‐[1,2,4]triazolo[4,3‐b][1,2,4]triazole: A Non‐toxic, High‐Performance Energetic Building Block with Excellent Stability

Abstract

A novel strategy for the design of energetic materials that uses fused amino-substituted triazoles as energetic building blocks is presented. The 3,6,7-triamino-7H-[1,2,4]triazolo[4,3-b][1,2,4]triazolium (TATOT) motif can be incorporated into many ionic, nitrogen-rich materials to form salts with advantages such as remarkably high stability towards physical or mechanical stimuli, excellent calculated detonation velocity, and toxicity low enough to qualify them as "green explosives". Neutral TATOT can be synthesized in a convenient and inexpensive two-step protocol in high yield. To demonstrate the superior properties of TATOT, 13 ionic derivatives were synthesized and their chemical- and physicochemical properties (e.g., sensitivities towards impact, friction and electrostatic discharge) were investigated extensively. Low toxicity was demonstrated for neutral TATOT and its nitrate salt. Both are insensitive towards impact and friction and the nitrate salt combines outstanding thermal stability (decomposition temperature=280 °C) with promising calculated energetic values.

Crystal Structures of Furazanes

“…The two nitramino moieties are also tilted out of the furazan plane by 44.0° (N6-N5-C1-C2). The two cations have a planar structure except for the two protons located at N13 as reported previously in the literature [4]. As in salt 8, an intensive hydrogen bond network is formed between the three amino groups of the cation and the nitro and nitramino groups of the anion, which makes the salt 12 stable up to 266 °C The bond distances of the anion (C1-C2 = 1.…”

“…The cation has a planar structure except for the two protons located at N13 as reported previously in the literature [4]. All the three amino groups in the cation form hydrogen bonds to the nitro and nitramino groups of the anion, resulting in a strong hydrogen-bonding network.…”

“…We recently reported on the two nitrogen-rich cations 4,4',5,5'-tetraamino-3,3'-bi-triazolium [3] and 3,6,7-triamino [1,2,4]triazolo [4,3-b] [1,2,4]triazolium [4], which can form thermally stable energetic salts. With these two nitrogen-rich cations in hand, we have now synthesized several new ionic furazanes to increase the decomposition temperatures of previously known 3-nitramino-4-nitrofurazan 4 [5] and dinitraminoazoxyfurazan 10 [6].…”

“…Compound 3 can be easily nitrated under relatively "mild" conditions with N2O5 to give 3-nitramino-4-nitrofurazan 4 [5]. The energetic salts hydroxylammonium 3-nitramino-4-nitrofurazan 5, ammonium 3-nitramino-4-nitrofurazan (6), 4,4',5,5'-tetraamino-3,3'-bi-triazolium di-3-nitramino-4-nitrofurazan 7 and 3,6,7-triamino- [1,2,4]triazolo [4,3-b] [1,2,4]triazolium 3-nitramino-4-nitrofurazan 8 can be synthesized by treating compound 4 with the respective base.…”

“…Compound 9 was then stirred in nitric acid (100%) to nitrate the two amino groups to obtain dinitraminoazoxyfurazan 10 [6]. Two thermally stable derivatives 4,4',5,5'-tetraamino-3,3'-bi-triazolium dinitraminoazoxyfurazan 11 and di-3,6,7-triamino- [1,2,4]triazolo [4,3-b] [1,2,4]triazolium dinitraminoazoxyfurazan 12 were obtained by treating the acid 10 with the corresponding bases.…”