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

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^-1K^-1, 257.52 kJ mol^-1, and 295.59 kJ mol^-1, respectively.