Studies on thermal decomposition and explosive properties of some novel metal complexes of aryl mercapto tetrazoles

Abstract Several energetic metal complexes of aryl mercapto tetrazoles have been investigated for their thermal decomposition and explosive properties. Peak decomposition temperatures and the enthalpy of decomposition data have been used to assess the thermal reactivity of the ligands and their corresponding metal complexes. Among the different ligands studied, ortho nitro phenyl mercapto tetrazole (ONPMT) is the most thermally sensitive one, thus confirming the tetrazole group to be a trigger group. Metal complexes (with metal ions from 3d transition metal ion series and heavy metal ions such as Hg (II) and Pb (II) ions) synthesised with ONPMT exhibit a high degree of explosive sensitivity, comparable to other primary explosives. While Ag(I)-ONPMT complex is the most sensitive, the chloro complex of Ni (II) is the most stable one. Attempts have been made to explain the thermal and explosive sensitivity characteristics of the metal-ligand complexes keeping in view the various physico-chemical factors affecting sensitivity. Some preliminary structure - property correlations could be drawn. Standard performance tests carried out on a few tetrazole-metal complexes reveal that their performance is comparable to that of lead styphnate. These complexes are, however, inferior in their initiating strength with respect to dextrinated lead azide, perhaps due to their lower bulk density.