A novel compound [Mn(H2O)6](AMTZ)2(PA)2 (AMTZ = 4-amino-3,5-dimethyl-1,2,4-triazole and PA = Picrate) with Extensive hydrogen bonds: Synthesis, structure and thermal characters

Abstract

The title compound 1, (Mn(H2O)6)(AMTZ)2(PA)2, contains 4-animo-3,5-dimethyl-1,2,4-triazole (AMTZ) and picrate (PA) and was characterized by elemental analysis, FT-IR spectroscopy and Single-Crystal X-ray diffraction. The space group of compound 1 is triclinic P-1(2), with a = 6.797(2) u A, b = 9.800(3) u A, c = 13.197(4) u A, =, =, =. The central Mn 2+ is octahedral and surrounded by two kinds of centrosymmetric molecules, AMTZ and PA. The compound has an extended 3-D supramolecular structure due to water molecules coordinated though hydrogen bonds to the nitrogen and oxygen atoms and the offset face-to- face π ··· π packing. The differential scanning calorimetry (DSC) analysis shows that two exothermic processes take place at 341.4 ◦ C and 473.9 ◦ C. The kinetic parameter of the first exothermic process was studied using Kissinger's method and Ozawa's method. This provided the enthalpy of formation (−3337.7 kJ·mol −1 ), critical temperature of thermal explosion (588.79 K). The entropy of activation (� S / = ), enthalpy of activation (� H / = ), and free energy of activation (� G / = ) were, respectively, -209.78 J·K −1 ·mol −1 , 155.50 kJ·mol −1 and 267.75 kJ·mol −1 . A flame sensitivity test showed that the 50% firing height (h50) was 20 cm.