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

• Published in: Chemistry, an Asian journal an Asian journal, 2019-06, Vol.14 (11), p.2018-2028
• Main Authors: Wurzenberger, Maximilian H. H., Gruhne, Michael S., Lommel, Marcus, Szimhardt, Norbert, Klapötke, Thomas M., Stierstorfer, Jörg
• Format: Article
• Language: English
• Subjects: Chemistry; Coordination compounds; Copper; copper(II); Detonators; Electrostatic discharges; energetic coordination compounds; energetic materials; explosives; Impact tests; laser ignition; Ligands; PETN; Sensitivity; Silver; Tetrazoles; Transition metal compounds
• ISSN: 1861-4728; 1861-471X
• DOI: 10.1002/asia.201900269

Energetic coordination compounds (ECC) based on 3d or 4d transition metals show promising characteristics to be used as potential replacements for highly toxic lead‐containing 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 ligands as well as various central metals (Cu2+, Fe2+, Zn2+, Ag+) and 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, and DTA as well as their sensitivities toward impact and 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. Classical initiation tests (nitropenta filled detonators) and ignition by laser irradiation highly prove the potential use of the most promising compounds in lead‐free initiation systems. Being very energetic: The performance of energetic coordination compounds (ECC) can be easily adjusted to the desired properties by varying one of their building blocks. In this study, the substitution of one proton of 1‐ethyltetrazole with an azide group and the comparison of the analog complexes by applying both ligands is discussed. ECC, consisting of the azide‐ligand, show promising performances, making them potential lead azide replacements.