1‐ and 2‐Tetrazolylacetonitrile as Versatile Ligands for Laser Ignitable Energetic Coordination Compounds

2-(1H-Tetrazol-1-yl)acetonitrile (1-TAN), 2-(2H-tetrazol-2-yl)acetonitrile (2-TAN), 5-((1H-tetrazol-1-yl)methyl)-1H-tetrazole (1-HTMT) and 5-((2H-tetrazol-2-yl)methyl)-1H-tetrazole (2-HTMT) were used as nitrogen-rich ligands for energetic coordination compounds (ECCs). The obtained energetic materials were analyzed concerning their physiochemical properties, providing viable data on the safety of handling. The properties in laser-ignitable primers and in lead-free detonator assemblies were evaluated.

Abstract

1- and 2-Tetrazolylacetonitrile (1- and 2-TAN) have been synthesized by the reaction of chloroacetonitrile with 1H-tetrazole under basic conditions. They further were reacted with sodium azide in the presence of zinc(II) chloride to form 5-((1H-tetrazol-1-yl)methyl)-1H-tetrazole (1-HTMT) and 5-((2H-tetrazol-2-yl)methyl)-1H-tetrazole (2-HTMT). The nitrogen-rich compounds have been applied as ligands for Energetic Coordination Compounds (ECCs) and show interesting coordinative behavior due to different bridging modes. The structural variability of the compounds has been proved by low-temperature X-ray analysis. The ECCs were analyzed for their sensitivities to provide information about the safety of handling and their capability to serve as primary explosives in detonator setups to replace the commonly used lead styphnate and azide. All colored ECCs were evaluated for their ignitability by laser initiation in translucent polycarbonate primer caps. In addition, the spin-crossover characteristics of [Fe(1-TAN)₆](ClO₄)₂ were highlighted by the measurement of the temperature-dependent susceptibility curve.

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