# Safe Stockpiling of the MTX‑1 Primary Explosive in Alkali or Alkaline Earth Metal Complexes and Coordination Polymers

## TL;DR

This paper explores how to safely store the explosive MTX-1 by forming stable complexes with metal ions, reducing its sensitivity to heat and mechanical stress.

## Contribution

The study identifies specific metal ions that form the most stable complexes with MTX-1, offering a safer storage method for this explosive material.

## Key findings

- MTX-1 forms stable complexes with Mg²⁺, Ca²⁺, and Li⁺, which are insensitive to mechanical and thermal stimuli.
- Larger metal ions like Na⁺, Sr²⁺, and Ba²⁺ form one-dimensional coordination polymers with MTX-1.
- Thermal treatment of these complexes leads to water loss and slight sensitivity, but they can be rehydrated in moist air.

## Abstract

The safe stockpiling of high-energy combustible and explosive
materials
is important for environmental and human population protection, particularly
in mining and military areas. MTX-1 (2-(tetrazol-5-yl-diazenyl)­guanidine)
is used in percussion primer compositions that react rapidly with
the hydroxides of alkali or alkaline earth metals to form complexes
of diverse composition. These are insensitive to mechanical stimuli
and to intense heat under high confinement. The most stable complexes
were found to be those with ions having the smallest effective ion
radii (Mg2
+ and Ca2
+),
followed by Li+. These complexes form discrete mononuclear
(Mg2
+ and Ca2
+) or dimeric
(Li+) structures in the solid state. One-dimensional (1D)
(Na+, Sr2
+, and Ba2
+), 2D (K+ and Rb+), and 3D (Cs+) coordination polymeric structures were found for the remaining
complexes with larger ions. Detailed topological analysis of the electron
density and quantitative estimation of π–π stacking
interactions were performed. Complexes could be used for intense flame
coloring in pyrotechnics. Upon thermal treatment of complexes over
∼200 °C, water is lost from the coordination sphere of
the metal ion, which leads to materials that are slightly sensitive
and rehydrate in moist air. Recovery of insoluble MTX-1 is possible when these complexes are treated with an aqueous acid.