Safe 5-nitrotetrazolate anion transfer reagents

Abstract

Silver 5-nitrotetrazolate (1) and copper(II) 5-nitrotetrazolate 5-nitrotetrazole dihydrate (2) are useful reagents for the synthesis of 5-nitrotetrazole (NT) salts. Both compounds were synthesized and characterized by vibrational spectroscopy (IR and Raman) and differential scanning calorimetry (DSC). In addition, their sensitivity towards friction, shock and electrostatic discharge was tested by standard BAM methods. The extremely high sensitivity of both materials makes the transfer of the NT⁻ anion using 1 and 2 hazardous and not suitable for up-scaling. In order to diminish the hazards involved with the transfer of the energetic anion and to render the synthesis of NT salts suitable for an industrial scale the two compounds were stabilized by coordination with a chelating ligand and silver(ethylendiamine) 5-nitrotetrazolate (3) and bis(ethylendiamine)copper(II) 5-nitrotetrazolate (4) were synthesized in high yields. Both the stabilized NT⁻ anion transfer reagents were characterized by analytical and spectroscopic methods. In addition, the crystal structure of the ethylendiamine copper complex (4) was determined: orthorombic, Pbca; a = 7.5200(1), b = 14.0124(2), c = 14.7740(2) Å; V = 1556.78(4) ų. Furthermore, we synthesized triaminocopper(II) 5-nitrotetrazolate (5), which has potential as a more environmentally-friendly primary explosive. Lastly, the synthetic potential of the ethylediamine adducts 3 and 4 to form energetic salts of NT was investigated.