Crystal structure and thermochemistry of a novel coordination compound 2-pyrazine carboxylate sodium

Abstract

2-Pyrazine carboxylate sodium Na2(PCA)2(s) was synthesized. X-ray crystallography was applied to characterize its crystal structure. Chemical and elemental analyses were used to determine its composition and purity. A precise automatic adiabatic calorimeter was used to measure heat capacities in the temperature range from 78 to 400 K. A polynomial equation of experimental molar heat capacities as a function of the temperature was obtained. The smoothed molar heat capacities and thermodynamic functions of the compound were calculated. The standard molar enthalpies of dissolution for the reactants and products of the synthesis reaction in the selected solvent were measured by an isoperibol solution-reaction calorimeter. The enthalpy change of the reaction was determined to be (1.70 ± 0.82) kJ mol−1, and the standard molar enthalpy of formation of the complex was derived to be −(1,108.70 ± 2.51) kJ mol−1. In addition, the reliability of the designed thermochemical cycle was verified by UV–Vis spectra.