Highly functional energetic complexes: stability tuning through coordination diversity of isomeric propyl-linked ditetrazoles

Abstract

A series of functional new energetic coordination compounds (ECCs) were prepared and their physicochemical properties tuned by the use of various metal(ii) centers and three different ditetrazolylpropane isomers.

A Smart Access to the Dinitramide Anion – The Use of Dinitraminic Acid for the Preparation of Nitrogen‐Rich Energetic Copper(II) Complexes

“…All used ligands (Scheme 2 ) were either purchasable (NH 3 , ATRI) or synthesized using literature known procedures. Tetrazole derivatives were either prepared by the reaction of alkyl halides (MAT, dtm, 2,2‐dte, 1,2‐dtp) or dimethyl sulfate (1‐MTZ) with 1,5 H ‐tetrazole[ 9b , 13a , 14 , 20a , 21 ] and through ring closure reactions using sodium azide, triethyl orthoformate, and the respective alkyl amine or diamine (AET, AMT, 1,1‐dte, idtp, dtb). [ 13b , 22 ] For the syntheses of the complexes, freshly prepared aqueous solutions of copper(II) dinitramide as well as stochiometric amounts of the respective ligands were combined (Scheme 3 & Scheme 4 ) and the resulting reaction mixtures were left for crystallization at ambient conditions.…”

“…The crystalline materials were filtered off, washed with a small amount of ice‐cold water when necessary and dried in air overnight. The use of other common monotetrazoles such as 1‐amino‐5 H ‐tetrazole, [17] 1,5‐dimethyltetrazole, [23] 1,5‐diaminotetrazole, [24] and 1‐methyl‐5‐aminotetrazole [25] or ditetrazoles such as di(tetrazol‐2‐yl)propane, [9b] which have already been successfully used as ligands, did not result in isolable crystalline ECC. One factor that could play a crucial role here is that in our synthesis we were limited to the solvent water because of the ion exchange and could not use organic solvents such as acetonitrile.…”

“…already showed that the implementation of propylene bridged ditetrazoles in complexes can increase thermal stability through the linking of the ligand between several metal centers. [9b] Furthermore, a comparison of the previously known complexes shows that probably none of them is able to successfully initiate PETN. Therefore, the focus should also lie on the incorporation of ligands that are known to enhance the performance of the complexes by their high positive heat of formation.…”

“…Typically, a mixture of ammonium dinitramide with any copper(II) salt is reacted with the respective ligand. [9b] Alternatively, a copper(II) complex with any anion and the desired ligand is formed in solution and a dinitramide salt is added. [8] Thus, in every case, ions are left behind which can contaminate the sample or lead to a wrong composition of the complex.…”

Toxicity Assessment of Energetic Materials by Using the Luminescent Bacteria Inhibition Test

“…Due to the toxicity of the copper(II)metal towards microorganisms [38], similar results were observed for the copper(II)complexes 31 – 33 , which were more toxic compared to their used ligands only (Table 6). Those propyl‐linked bitetrazoles ( 28 – 30 ) have a little variation in their substitution pattern, but the EC 50 values are in the range of 0.36 g L −1 ( 30 ) to 10.30 g L −1 ( 28 ) [39]. Whereby, the 2,2‐substituted is the most toxic, followed by 1,2‐substitued and the 1,1‐substituted is the non‐toxic tetrazole.…”