Nitrogen-Rich 5-(1-Methylhydrazinyl)tetrazole and its Copper and Silver Complexes

Nitrogen-rich 5-(1-methylhydrazinyl)­tetrazole (<b>1</b>, MHT) was synthesized by using a straightforward method. White plate crystals of <b>1</b> were isolated in acetonitrile and crystallized in the monoclinic system <i>P</i>2₁/<i>c</i> (# 14) (<i>a</i> = 3.8713(18) Å, <i>b</i> = 12.770(6) Å, <i>c</i> = 9.974(5) Å, α = 90°, β = 93.397(6)°, γ = 90°, <i>V</i> = 492.3(4) ų, <i>Z</i> = 4). The reactions of Cu­(II) and Ag­(I) ions in aqueous solution with <b>1</b> were investigated and found to form two complexes under mild conditions. The crystal structures of <b>2</b> and <b>3</b> are discussed with respect to the coordination mode of the MHT anion. Thermal stabilities were determined from differential scanning calorimetry (DSC) combined with thermogravimetric analysis (TGA) tests. Impact sensitivity was determined by BAM standards showing that these MHT salts are insensitive to impact (>40 J) confirmed by UN standards. The energies of combustion of <b>1</b>–<b>3</b> were determined using oxygen bomb calorimetry values and were used to obtain the corresponding enthalpies of formation. Combined with these data above, the neutral MHT is an attractive nitrogen-rich ligand for metallic energetic materials. Its copper and silver coordinated complexes are of interest as potential “green” metal energetic materials with high thermal stability as well as low sensitivity to impact and a high molar enthalpy of formation