Comparison of 1‐Ethyl‐5H‐tetrazole and 1‐Azidoethyl‐5H‐tetrazole as Ligands in Energetic Transition Metal Complexes

Abstract

Energetic coordination compounds (ECC) based on 3d or 4d transition metals show promising characteristics to be used as potential replacements for highly toxic leadcontaining primary explosives. Herein we report the synthesis of 12 new ECC based on 1-azidoethyl-5H-tetrazole (AET) or 1-ethyl-5H-tetrazole (1-ETZ) as nitrogen-rich ligandsa s well as variousc entral metals (Cu 2 + ,F e 2 + ,Z n 2 + ,A g + )a nd anions such as perchlorate and nitrate. The influence of the increased endothermicity by adding an additional azide group was studied by comparing analogous ECC based on AET and 1-ETZ. Furthermore, the compounds were extensively analyzed by XRD, IR, EA, solid-state UV/Vis,a nd DTAa s well as their sensitivities toward impactand friction were determined with BAM standard techniques, together with their sensitivity against electrostatic discharge. The sensitivities were compared with the one toward ball drop impact measurements. Classicali nitiation tests (nitropenta filled detonators) and ignitionbylaser irradiation highly prove the potential use of the most promising compounds in lead-freei nitiation systems.[a] M.

1‐Amino‐5‐methyltetrazole in Energetic 3 d Transition Metal Complexes – Ligand Design for Future Primary Explosives

“…While [Cu(1‐AT) 6 ](ClO 4 ) 2 and [Fe(1‐AT) 6 ](ClO 4 ) 2 do not possess a no‐fire‐limit towards friction stimuli, compounds 2 – 5 could successfully be improved. The stability increases in the following order: Fe 2+ <Cu 2+ <Mn 2+ <Zn 2+ – which is in accordance with our previous findings [20]. While the aqua ligand in 4 does not seem to strongly affect the stability of the complex, the two aqua ligands in [Cu(1‐MAT) 4 (H 2 O) 2 ](ClO 4 ) 2 have a highly stabilizing effect.…”

Comparison of 1-Propyl-5H-tetrazole and 1-Azidopropyl-5H-tetrazole as Ligands for Laser Ignitable Energetic Materials

“…In the row of perchlorate complexes, the temperature stability is increasing in the following order: Fe 2+ < Cu 2+ < Zn 2+ < Mn 2+ , which is in accordance with previous findings. 17 Comparing analogous complexes based on the different ligands APT and PT, the clear trend of higher stability for compounds based on 2 is observable. While the free nitrogen-rich molecules only show a difference of 11 °C, the iron(II) and copper(II) perchlorate composed complexes deviate 56 and 44 °C, respectively.…”

“…For the synthesis of the new ligand 1azidopropyl-5H-tetrazole (1), a simple two-step synthesis was performed similar to that of 1-azidoethyl-5H-tetrazole (Scheme 1). 17 The starting material 3-chloropropylamine hydrochloride is a cheap commercially available molecule, which can be reacted…”

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

“…Thus, similar effects in copper complexes based on these ligands have already been observed in previous works of our group. 39,40 The third complex having a 2D structure, [Cu 4 (N 3 ) 8 (2-MAT) 2 ] (9), is showing a sufficient thermal stability of 161 °C, however measurements regarding compound 3 and 4, only forming 1D polymeric chains, gave exothermic events at the same or even higher temperatures (3: T exo = 161 °C; 4: T exo = 170 °C). Accordingly, the hydrogen bonding specifically formed by the amino groups of the ligands in 3 and 4 are believed to counterbalance the effects of a 2D polymer on the thermal stabilities of a complex.…”