Low-Temperature Heat Capacities and Standard Molar Enthalpy of Formation of Dichloro Bis(2-aminopyridine) Zinc (II), ZnCl2(C5H6N2)2(s)

Abstract

Dichloro bis(2-aminopyridine) zinc (II), ZnCl 2 (C 5 H 6 N 2 ) 2 (s), was synthesized by the method of solvonthermal synthesis in which 2-aminopyridine and zinc chloride were chosen as the reactants. X-ray crystallography, chemical analysis, and elemental analysis were applied to characterize the structure and composition of the complex. Low-temperature heat capacities of the title compound were measured with a precise small-sample automated adiabatic calorimeter over the temperature range from 78 K to 398 K. A polynomial equation of the heat capacities as a function of temperature was fitted by a least-squares method. Smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature (298.15 K) were calculated and tabulated at intervals of 5 K based on the fitted polynomial. A reasonable thermochemical cycle was designed, and the standard molar enthalpies of dissolution for the reactants and products of the synthesis reaction in a selected solvent were measured by an isoperibol solution-reaction calorimeter. In addition, the enthalpy change of the reaction was calculated from the data of the above standard molar enthalpies of dissolution. Finally, the standard molar enthalpy of formation of the complex ZnCl 2 (C 5 H 6 N 2 ) 2 (s) was determined to be −(400.52±1.66) kJ·mol −1 in accordance with Hess's law.

Synthesis, crystal structure, spectroscopic study and Hirshfeld surface analysis of [Ni(C6H8N2)3]Cl2.2(H2O) (1)

“…The bi-functional organic amine 2-aminomethylpyridine include a pyridine ring and an aliphatic amine group is an excellent choice as an organicinorganic synthesis model. It is used in large-scale industrial applications [6], it is also used for analytical chemistry and medical detection [7]. In addition, some metal-pyridine coordination compounds have been explored for the design of novel nonlinear optical materials [8].…”