The experimental and theoretical chemistry of 1,2,3,4-tetrazines have been actively studied in the last 20 years. The increasing interest in this class of compounds is due to the fact that the 1,2,3,4-tetrazine ring is a promising building block for the development of energetic and physiologically active compounds. The review considers various types of 1,2,3,4-tetrazines including completely unsaturated nonannulated tetrazines and their N-oxides; nitrogen-substituted tetrazines; annulated tetrazines with a nitrogen atom common to two heterocycles; 1,2,3,4-tetrazine 1,3-dioxides fused to benzene, pyridine, 1,2,3-triazole or 1,2,5-oxadiazole ring; and also 1,2,3,4-tetrazine 1,3-dioxide fused to one more 1,2,3,4-tetrazine 1,3-dioxide ring. Methods of synthesis and reactivity of these compounds, their crystallographic features, spectral characteristics and thermal stability are described. The results of quantum chemical studies for 1,2,3,4-tetrazine derivatives are presented. The prospects of using 1,2,3,4-tetrazines as energetic compounds are discussed. The bibliography includes 189 references.

A strategy for the synthesis of 5-((2-cyanoethyl)-X-amino)-[1,2,3]triazolo[4,5-c][1,2,5]oxadiazol-5-ium-4-ides (X = H; CH₂CH₂CN; NO₂ (4a); CN (4b); CO₂Et (4c)) starting from 3-amino-4-azido-1,2,5-oxadiazole was developed. The key step in this strategy is the intramolecular thermolytic cyclization of the azido group and the bis(2-cyanoethyl)triazene group. Removal of the 2-cyanoethyl protecting group from amides 4a–c gave potassium salt of the corresponding nitramide and sodium salts of cyano- and ethoxycarbonylamide. The structure and thermal stability of the synthesized compounds were studied experimentally using multinuclear NMR spectroscopy, X-ray crystallography, thermogravimetry, and differential scanning calorimetry.

A comparative study of structures, stability and energetic performance of ammonium and hydrazinium salts of 4H-[1,2,3]triazolo[4,5-c][1,2,5]oxadiazole (triazolofurazan, TF) as well as its N-oxide and N-nitroimide was performed.

The synthesis verification of 3-amino-4-azido-1,2,5-oxadiazole and its structural characterization by IR, NMR spectroscopy, X-ray diffraction, and elemental analysis have been carried out. Its thermal behavior (TG-DSC), standard enthalpy of formation, sensitivity to mechanical stimuli, and detonation parameters have been studied. Our study has revealed the broad prospects of 3-amino-4-azidofurazan application as a precursor to novel energetic materials.