Parent 1,4-dihydro-[1,2,3]triazolo[4,5-d][1,2,3]triazole and its derivatives as precursors for the design of promising high energy density materials†

The design of novel high energy density materials (HEDMs) is still one of the significant challenges in the field of applied chemistry. Newly discovered scaffolds are rare, but they open up new possibilities for HEDM design. Herein, a simple and effective two-step approach to previously unknown 1,4-dihydro-[1,2,3]triazolo[4,5-d][1,2,3]triazole (1) is presented. This compound is an individual energetic material (d = 1.84 g cm⁻³, , T_onset = 193 °C (all experimental values), D = 8.5 km s⁻¹, P = 34 GPa (calculated ones)), but may also serve as a scaffold for the synthesis of structurally diversified related compounds. The precursors of triazolo–triazole 1 are previously unknown 5-amino-4-diazo-4H-1,2,3-triazolium chloride (4) and 5-amino-4-diazo-4H-1,2,3-triazole (5), which can also serve as starting materials for the synthesis of a variety of novel heterocycles. For example, the diazo compound 5 was used for the regioselective synthesis of a 2,5-disubstituted triazolo–triazole 10 bearing an N₄-tripoid fragment. Overall, the developed approach to triazolo–triazole 1, 5-amino-4-diazo-4H-1,2,3-triazolium chloride (4) and 5-amino-4-diazo-4H-1,2,3-triazole (5) is expected to make these high nitrogen systems more accessible and affordable for the design of nitrogen containing fused heterocycles.