Advancement and stabilization of copper(ii) azide by the use of triazole- and tetrazole ligands – enhanced primary explosives

Abstract

Copper(II) (cupric) and copper(I) (cuprous) azide are both very powerful primary explosives with good thermal stabilities. However, both suffer from extreme sensitivities, which makes them unsuitable for any application. One brilliant concept for the synthesis of new ecofriendly, non-water soluble, and very powerful primary explosives is the assembly of ligands in the coordination sphere of copper(II) azide. Blocking of possible coordination sites through endothermic azoles allows the desensitization of copper(II) azide and leads to compounds with manageable sensitivities. 13 different nitrogen-rich tri- and tetrazole derivatives were used for the synthesis of energetic copper(II) azide complexes. The water insoluble compounds are highly promising candidates for the replacement of lead and perchlorate containing primary explosives. For the characterization, the complexes were analyzed by single crystal X-ray diffraction, elemental analysis (EA), infrared (IR) spectroscopy, and differential thermal analysis (DTA) measurements with heating rates of 5 °C min⁻¹. The bulk material purity of selected complexes was confirmed by X-ray powder diffraction. The sensitivities toward impact (IS), friction (FS), and electrostatic discharge (ESD) of all synthesized compounds were tested and determined according to BAM (Bundesanstalt für Materialforschung und -prüfung) standards. The most promising compounds were investigated in copper shell initiation experiments with PETN as main charge.