Crystal structure and thermochemical properties of a novel coordination compound sodium pyruvate C₃H₃O₃Na(s)

Graphical abstract: A novel coordination compound sodium pyruvate C₃H₃O₃Na(s) is synthesised. Elemental analysis and X-ray crystallography are used to characterise the composition and crystal structure of the compound. The lattice potential energy and ionic volume of the anion are obtained from crystallographic data. The standard molar enthalpy of formation of the compound is calculated by an isoperibol solution-reaction calorimeter. Molar enthalpies of dissolution of the compound at various molalities are measured at T = 298.15 K. According to Pitzer’s theory, molar enthalpy of dissolution of the title compound at infinite dilution is calculated. The values of relative apparent molar enthalpies and relative partial molar enthalpies of the solvent and the compound at different concentrations m/(mol · kg⁻¹) are derived. - Highlights: • The sodium pyruvate was synthesised and crystal structure was determined. • The enthalpy change of the synthesis reaction was obtained. • Standard molar enthalpy of formation was obtained. • Molar enthalpy of dissolution at infinite dilution was calculated. - Abstract: A novel coordination compound sodium pyruvate C₃H₃O₃Na(s) is synthesised by a liquid phase reaction. The compound has an obvious bioactivity and can be used as the biological carbon source and the chemical identification of primary and secondary alcohols. It can be also used to determinate transaminase. Elemental analysis and X-ray crystallography are used to characterise the composition and crystal structure of the compound. Single crystal X-ray analysis reveals that the compound is formed by one CH₃COCOO⁻ anion and one Na⁺ cation. An obvious feature of the crystal structure is the formation of the five-membered chelate ring by the coordination of O1 of carboxylate and O3 of keto form with Na⁺ cation, and it is good for the stability of the compound in structure. The lattice potential energy and ionic volume of the anion are obtained from crystallographic data. In accordance with Hess’ law, a reasonable thermochemical cycle is designed according to the practical synthesis reaction of the compound and the standard molar enthalpy of formation of the compound is calculated as an important physical quantity in chemical thermodynamics by use of an isoperibol solution-reaction calorimeter. Molar enthalpies of dissolution of the compound at various molalities are measured at T = 298.15 K in the double-distilled water. According to Pitzer’s electrolyte solution theory, molar enthalpy of dissolution of the title compound at infinite dilution is calculated to be Δ_sH_m^∞ = (19.81 ± 0.69) kJ · mol⁻¹. The values of relative apparent molar enthalpies (^ΦL) and relative partial molar enthalpies of the solvent (L^¯₁) and the compound (L^¯₂) at different concentrations m/(mol · kg⁻¹) are derived from the experimental values of the enthalpies of dissolution of the compound