Synthesis, characterization, and thermochemistry of the solid state coordination compound Zn(Nic)2 · H2O(s) (Nic = nicotinic acid)

A novel compound, viz.   zinc nicotinate monohydrate, was synthesized by the method of room temperature solid phase synthesis. The techniques of FT-IR chemical and elemental analyses and X-ray powder diffraction were applied to characterise the structure and composition of the complex. In accordance with Hess’ law, a thermochemical cycle was designed and the enthalpy change of the solid phase reaction of nicotinic acid with hydrated zinc acetate was determined to be ΔrHm∘=(46.71±0.21)kJ·mol-1 by use of an isoperibol solution-reaction calorimeter. The standard molar enthalpy of formation of the title complex Zn(Nic)2 · H2O(s) was calculated as −(1062.3 ± 2.0) kJ · mol−1 by use of the enthalpies of dissolution and other auxiliary thermodynamic data.