Synthesis, crystal structure, thermal decomposition, and explosive properties of [Bi(tza)₃]_n (tza = tetrazole acetic acid)

Abstract

A coordination compound based on tetrazole acetic acid (Htza) and bismuth(III), [Bi(tza)₃] _n , was synthesized and characterized by single crystal X-ray diffraction analysis, elemental analysis, FT-IR, and ¹H NMR spectroscopy. The crystallographic data show that the crystal belongs to monoclinic, P2₁/n space group, a = 0.91968(19) nm, b = 0.94869(19) nm, c = 1.7824(4) nm, β = 101.488(3)°, and Z = 4. The central bismuth(III) is nine-coordinate by three nitrogens from three tetrazole rings and six oxygens of the carboxylate of another three tza⁻ ions, with each tza⁻ tridentate, chelating, bridging coordination. The coordination bonds and the intramolecular hydrogen bonds make the complex pack into a layered structure in polymer form. The thermal decomposition mechanism of the title complex was investigated by DSC and TG-DTG techniques. Under nitrogen at a heating rate of 10°C min⁻¹, thermal decomposition of the complex contains two intense exothermic processes between 217.4°C and 530.3°C in the DSC curve; the final decomposed residue at 570°C was Bi₂O₃. Sensitivity tests showed that [Bi(tza)₃] _n was sensitive to impact and flame stimulus.

Keywords:

• Bismuth
• Tetrazole acetic acid
• Crystal structure
• Thermal decomposition
• Sensitivity

Acknowledgments

This project was financially supported by Science and Technology fund on Applied Physical Chemistry Laboratory (No. 9140C3703051105), fund of the State Key Laboratory of Explosion Science and Technology (No. YBKT10–05 and ZDKT10–01b), and Program for New Century Excellent Talents in University (No. NCET–10–0051 and No. CNET–09–0051).