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

Nitrogen-rich 5-(1-methylhydrazinyl)­tetrazole (1,
MHT) was synthesized by using a straightforward method. White plate
crystals of 1 were isolated in acetonitrile and crystallized
in the monoclinic system P21/c (# 14) (a = 3.8713(18) Å, b = 12.770(6) Å, c = 9.974(5) Å, α
= 90°, β = 93.397(6)°, γ = 90°, V = 492.3(4) Å3, Z = 4).
The reactions of Cu­(II) and Ag­(I) ions in aqueous solution with 1 were investigated and found to form two complexes under
mild conditions. The crystal structures of 2 and 3 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 1–3 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.