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.

Automated summary

Two new energetic salts were synthesized by combining 3,6-dihydrazinyl-1,2,4,5-tetrazine dichloride ([H2DHT]Cl2) and disodium 5,5'-azobis(tetrazolate) pentahydrate (Na2AZT·5H2O) under different pH conditions. Compound 2·2H2O was obtained under acidic conditions, while compound 3·4H2O was formed at neutral pH. Both compounds were characterized and compound 2·2H2O exhibited higher thermal stability compared to compound 3·4H2O.