Synthesis, structure, and thermal behavior of a 2-D polymeric Ca(II) compound with tetrazole-1-acetic acid

Abstract

A 2-D polymeric Ca(II) compound, [Ca(tza)₂(H₂O)₂] _n , was synthesized by the reaction of tetrazole-1-acetic acid with calcium carbonate. The product was characterized by X-ray single-crystal diffraction, elemental analysis, and IR spectroscopy. The calcium center is six-coordinate in a slightly distorted octahedral configuration by four carboxylic oxygens from four different tza⁻ ligands and two waters. The 2-D supramolecular laminar structure in b-axis × c-axis plane was constructed via four bridging tza⁻ ions connecting one Ca(II) with four adjacent Ca(II) ions. Differential scanning calorimetry and thermogravimetric–differential thermogravimetric analysis were applied to assess the thermal decomposition behavior. The kinetic parameters were obtained by non-isothermal reaction kinetics, and the Arrhenius equation can be expressed as lnk = 21.96–262.2 × 10³/RT. The values of critical temperature of thermal explosion, ΔS^≠ , ΔH^≠ , and ΔG^≠ were obtained as 574 K, −67.62 J mol⁻¹ K⁻¹, 257.52 kJ mol⁻¹, and 295.59 kJ mol⁻¹, respectively.

Keywords:

• Calcium complex
• Tetrazole-1-acetic acid
• Crystal structure
• Thermal behavior

Acknowledgments

We gratefully acknowledge the financial support from the National Natural Science Foundation of China (Nos. 10776002 and 20911120033), the Project of State Key Laboratory of Science and Technology (ZDKT08-01, YBKT10-03) and Doctoral Candidate Innovation Research Support Program by Science & Technology Review (kjdb201001-2).