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Three nitrogen-rich heterocyclic compounds containing the diamino-pyrimidine mono- N -oxide moiety were synthesized via mild oxidation reactions. Oxidation of the furazano-pyrimidine compound ( 1 ) with a mixture of trifluoroacetic anhydride (TFAA) and hydrogen peroxide (50%) gave the nitrate salt ( 3 ). All of the compounds were characterized by NMR spectra, elemental analysis, and single-crystal X-ray diffraction. They show high thermal stability and good detonation performance as well as low sensitivity. 

3,6-Diamino-1 H -[1,2,4]triazolo[4,3- b ][1,2,4]triazole ( 1 ) and its energetic salts ( 2–9 ) were designed and synthesized based on a fused-triazole backbone with two C-amino groups as substituents. Their physicochemical and energetic properties were measured or calculated. Among them, compound 1 exhibits superior thermostability ( T d (onset) : 261 °C), surpassing its analogues 3,7-diamino-7 H -[1,2,4]triazolo[4,3- b ][1,2,4]triazole (DATT, 219 °C) and 3,6,7-triamino-7 H -[1,2,4]triazolo[4,3- b ][1,2,4]triazole (TATOT, 245 °C). The differences in thermal stabilities were further investigated by determining the lowest bond dissociation energies (BDE) where a positive correlation between the stability of the molecules and the lowest BDE values is observed. The results show that 1 with the highest value for the lowest BDE has a superior thermostability in comparison to DATT and TATOT. The energetic salts ( 2–9 ) also exhibit remarkable thermal stabilities as well as low impact and friction sensitivities. The fused-triazole backbone 1 H -[1,2,4]triazolo[4,3- b ][1,2,4]triazole with two C-amino groups as substituents is shown to be a promising building block for construction of very thermally stable energetic materials.