Ph-Dependent Formation of Two Dihydrazinyltetrazine–Azobistetrazolate Salts with Different Thermal Stabilities and Energetic Performance

Two new energetic salts were prepared through the combination of 3,6-dihydrazinyl-1,2,4,5-tetrazine dichloride ([H2DHT]Cl2) and disodium 5,5 '-azobis(tetrazolate) pentahydrate (Na2AZT center dot 5H2O) in different pH conditions. Under acidic conditions, the 1:1 salt [H2DHT][AZT]center dot 2H2O (2 center dot 2H2O) was isolated, while neutral pH gave access to the formation of the 2:1 salt ([HDHT]2[AZT]center dot 4H2O; 3 center dot 4H2O). Both compounds were characterized by IR and NMR spectroscopy, thermal analysis (thermogravimetric analysis and differential scanning calorimetry), as well as single crystal and powder X-ray diffraction. Based on experimental data, compound 2 center dot 2H2O was found to be more thermally stable, with a decomposition temperature of Tdec = 107 degrees C, compared to compound 3 center dot 4H2O (Tdec = 99 degrees C). Non-covalent interactions (hydrogen bonds and N-N interactions) were evaluated to better understand the structure-property relationships, revealing the effect of crystal packing on the overall energetic properties.