Laser ignitable explosives are potential candidates in future applications for replacing toxic and very sensitive primary explosives, which are used in current devices. In this study, the literature unknown ligand 1-azidopropyl-5H-tetrazole (APT, 1) was synthesized for the first time and applied in energetic coordination compounds (ECC). The complexes are based on different 3d transition metals (Mn 2+ , Fe 2+ , Cu 2+ , and Zn 2+ ) as well as various oxidizing anions (NO 3 − , ClO 4 − , and ClO 3 − ) and were tested toward their capability as laser ignitable explosives. Furthermore, analogous complexes based on the literature known ligand 1-propyl-5H-tetrazole (PT, 2) were investigated for comparing the influence of the additional azide group toward the performance of the ECC. Toxicity measurements using Vibrio fischeri and the decreased sensitivities prove their usability as safer laser ignitable explosive with lower toxicities compared to currently used explosives.

For the first time, the highly sensitive 1-(nitratomethyl)-5H-tetrazole (1-NAMT) was synthesized, representing the shortest possible 1-(nitratoalkyl)-5H-tetrazole with a combined nitrogen and oxygen content of 81.4%. Compared to its related ethyl derivative, 1-(nitratoethyl)-5H-tetrazole, it exhibits improved oxygen balance, resulting in higher detonation parameters. 1-NAMT was thoroughly analyzed by single-crystal diffraction experiments accompanied by elemental analysis, IR spectroscopy, and multinuclear (1H, 13C, and 14N) NMR measurements. The thermal behavior of 1-NAMT was analyzed by differential thermal analysis supported by thermogravimetric analysis. Furthermore, energetic coordination compounds (ECCs) of Cu with different inorganic (e.g., nitrate, chlorate, and perchlorate) and nitroaromatic anions (e.g., picrate and styphnate) were synthesized and thoroughly analyzed. It is shown that the formation of ECCs with nitroaromatic anions (T dec ∼ 180 °C) is a suitable strategy to improve the rather low thermal stability of 1-NAMT (125 °C).

Energetic coordination compounds (ECCs) show promising properties to be used as potential substitutes for highly toxic lead-containing primary explosives. The concept is to combine the three building blocks: (i) ligand, (ii) transition metal, and (iii) anion, acting as (i) fuel, (ii) matrix, and (iii) oxidizer (e.g., ClO4 –, NO3 –, ClO3 –) or energetic component (e.g., DN–, N3 –, picrate, styphnate, trinitrophloroglucinate). By variation of the ligands, the complexes’ properties can be adjusted toward their desired performance and sensitivities. In the present study, 1-vinyl-5H-tetrazole (1-VTZ, 1) and 1-allyl-5H-tetrazole (1-ATZ, 2) were used as nitrogen-rich endothermic ligands to form 3d metal (Mn2+, Fe2+, Cu2+, Zn2+, Co2+, Ni2+)-based ECCs. The influence of the introduction of an unsaturated C–C bond (1-ETZ vs 1-VTZ and 1-PTZ vs 1-ATZ) on the performance and sensitivity of the complexes is discussed, as is the lengthening of the alkenyl chain (1-VTZ vs 1-ATZ). For further insights, the novel complexes were compared to literature-known complexes based on N1-substituted C2- and C3-derived tetrazole ligands, respectively. The ligand 1-VTZ (1) was prepared by elimination of hydrogen chloride from 1-(2-chloroethyl)-5H-tetrazole in methanolic KOH solution. 1-ATZ (2) was obtained by a heterocyclization reaction of allylamine with triethyl orthoformate and sodium azide in an acetic acid medium. All compounds were intensively characterized with analytical methods such as XRD, IR, EA, DTA, TGA, and sensitivity measurements (IS and FS). The energetic performances were visibly evaluated in fast heating experiments. Furthermore, PETN initiation and laser ignition experiments were carried out for promising ECCs.

5‐Methyl‐2,4,6‐trinitrobenzene‐1,3‐diol (trinitro‐orcinol, H2TNO) as a close structural relative to the well‐known energetic materials trinitroresorcinol (styphnic acid) and trinitrotoluene (TNT) is prepared in high purity and analyzed concerning its vapor pressure using the transpiration method. Several energetic coordination compounds (ECCs) of its respective anion were produced and compared with structurally close styphnate complexes to give an insight into physiochemical trends of the ECC. The synthesized compounds were further analyzed by elemental analysis, IR spectroscopy, differential thermal analysis and low temperature X‐ray diffraction analysis. To classify the reported compounds among the energetic materials, they were tested for their sensitivities towards mechanical stimuli such as impact, friction and electrostatic discharge as well as their behavior towards flame.

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