1,5-Dimethyltetrazole as a ligand in energetic 3d5 to 3d10-metal coordination compounds

During the last decade, energetic coordination compounds gained considerable attention due to the simple adjustments in their physicochemical properties. By combining different metal cations, energetic anions, and ligands, those compounds can be adapted for their intended use. This study used 1,5-dimethyltetrazole ( 3 ) as a highly endothermic, easily accessible, and insensitive ligand. It is a structural isomer to 1-ethyl-5 H -tetrazole (1-ETZ), which was recently described as a suitable ligand. 1,5-Dimethyltetrazole was synthesized using two different methods: (1) reaction of acetone with azido (trimethyl) silane and (2) reaction of acetoxime benzenesulfonate with sodium azide. Subsequently, 1,5-dimethyltetrazole was reacted with the perchlorate salts of different 3 d metals (e.g., Mn, Fe, Co, Ni, Cu, Zn) to obtain new energetic coordination compounds (ECCs). In addition, copper (II) complexes with 2,4,6-trinitro-phenolate anions were synthesized. The resultant complexes were investigated through low-temperature, single crystal diffraction experiments complemented by elemental analysis, infrared spectroscopy, and differential thermal analysis. Moreover, sensitivities towards impact and friction were investigated. In this study, all ECCs exhibited impact sensitivities between 2 and 10 ​J, friction sensitivities between 128 and 360 ​N, and thermal stabilities of up to 360 ​°C. 1,5-dimethyltetrazole (1,5-DMT) was synthesized using an easy, three-step synthesis procedure from cheap and commonly available starting materials, such as acetone, hydroxylamine, and sodium azide. Owing to its complete insensitivity and high thermal stability, 1,5-DMT serves as an ideal ligand for energetic coordination compounds (ECCs) when combined with 3d metals like copper (II) or zinc (II) perchlorate. Most ECCs exhibit excellent thermal stability together with safe handling. Despite no properties as primary explosives, they can be considered possible burning rate modifiers.