Energetic propane-1,3-diaminium and butane-1,4-diaminium salts of N,N'-dinitroethylenediazanide: syntheses, crystal structures and thermal properties.

The acidity of the amine H atoms and the consequent salt formation ability of ethylenedinitramine (EDNA) were analyzed in an attempt to improve the thermal stability of EDNA. Two short-chain alkanediamine bases, namely propane-1,3-diamine and butane-1,4-diamine, were chosen for this purpose. The resulting salts, namely propane-1,3-diaminium N,N'-dinitroethylenediazanide, C3H12N22+·C2H4N4O42-, and butane-1,4-diaminium N,N'-dinitroethylenediazanide, C4H14N22+·C2H4N4O42-, crystallize in the orthorhombic space group Pbca and the monoclinic space group P21/n, respectively. The resulting salts display extensive hydrogen-bonding networks because of the presence of ammonium and diazenide ions in the crystal lattice. This results in an enhanced thermal stability and raises the thermal decomposition temperatures to 202 and 221 °C compared to 180 °C for EDNA. The extensive hydrogen bonding present also plays a crucial role in lowering the sensitivity to impact of these energetic salts.