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.

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.