Energetic Salts of the Binary 5-Cyanotetrazolate Anion ([C2N5](-)) with Nitrogen-Rich Cations

The reaction of cyanogen (NC-CN) with MN3 (M=Na, K) in liquid SO2 leads to the formation of the 5-cyanotetrazolate anion as the monohemihydrate sodium (1 center dot 1.5H(2)O) and potassium (2) salts, respectively. Both 1 center dot 1.5H(2)O and 2 were used as starting materials for the synthesis of a new family of nitrogen-rich salts containing the 5-cyanotetrazolate anion and nitrogen-rich cations, namely ammonium (3), hydrazinium (4), semicarbazidium (5), guanidinium (6), aminoguanidinium (7), diaminoguanidinium (8), and triaminoguanidinium (9). Compounds 1-9 were synthesised in good yields and characterised by using analytical and spectroscopic methods. In addition, the crystal structures of 1 center dot 1.5 H2O, 2, 3, 5, 6, and 9 center dot H2O were determined by using low-temperature single-crystal X-ray diffraction. An insight into the hydrogen bonding in the solid state is described in terms of graph-set analysis. Differential scanning calorimetry and sensitivity tests were used to assess the thermal stability and sensitivity against impact and friction of the materials, respectively. For the assessment of the energetic character of the nitrogen-rich salts 3-9, quantum chemical methods were used to determine the constant volume energies of combustion, and these values were used to calculate the detonation velocity and pressure of the salts using the EXPLO5 computer code. Additionally, the performances of formulations of the new compounds with ammonium nitrate and ammonium dinitramide were also predicted. Lastly, the ICT code was used to determine the gases and heats of explosion released upon decomposition of the 5-cyanotetrazolate salts.