Energetic Salts Based on Monoanions of N,N‐Bis(1H‐tetrazol‐5‐yl)amine and 5,5′‐Bis(tetrazole)

Abstract

High-density energetic salts that contain nitrogen-rich cations and the 5-(tetrazol-5-ylamino)tetrazolate (HBTA(-)) or the 5-(tetrazol-5-yl)tetrazolate (HBT(-)) anion were readily synthesized by the metathesis reactions of sulfate salts with barium compounds, such as bis[5-(tetrazol-5-ylamino)tetrazolate] (Ba(HBTA)(2)), barium iminobis(5-tetrazolate) (BaBTA), or barium 5,5'-bis(tetrazolate) (BaBT) in aqueous solution. All salts were fully characterized by IR spectroscopy, multinuclear ((1)H, (13)C, (15)N) NMR spectroscopy, elemental analyses, density, differential scanning calorimetry (DSC), and impact sensitivity. Ba(HBTA)(2) x 4 H(2)O crystallizes in the triclinic space group P1, as determined by single-crystal X-ray diffraction, with a density of 2.177 g cm(-3). The densities of the other organic energetic salts range between 1.55 and 1.75 g cm(-3) as measured by a gas pycnometer. The detonation pressure (P) values calculated for these salts range from 19.4 to 33.6 GPa, and the detonation velocities (nu(D)) range from 7677 to 9487 m s(-1), which make them competitive energetic materials. Solid-state (13)C NMR spectroscopy was used as an effective technique to determine the structure of the products that were obtained from the metathesis reactions of biguanidinium sulfate with barium iminobis(5-tetrazolate) (BaBTA). Thus, the structure was determined as an HBTA salt by the comparison of its solid-state (13)C NMR spectroscopy with those of ammonium 5-(tetrazol-5-ylamino)tetrazolate (AHBTA) and diammonium iminobis(5-tetrazolate) (A(2)BTA).