Crystal structure, lattice potential energy, and thermochemical properties of a novel compound barium d-gluconate tetrahydrate

Abstract

A novel compound barium d-gluconate tetrahydrate, Ba[d-C6H11O7]2·4H2O, is synthesized and characterized by chemical analysis, elemental analysis, and X-ray crystallography. Single-crystal X-ray analysis reveals that the compound is formed by two d-gluconate anions, one barium (II) cation and four crystal water molecules. The compound exhibits an outstanding chelate property of d-gluconate anions to barium (II) cations, and the barium (II) cation is ten-coordinated and chelated by six d-gluconate anions. The molecules of the compound are further linked by intermolecular BaO and OH⋯O interactions to form a 3D supramolecular architecture. 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 and the standard molar enthalpy of formation of Ba[d-C6H11O7]2·4H2O(s) is calculated as ΔsHm [Ba[d-C6H11O7]2·4H2O, s]=−(4712.85±1.06)kJ·mol−1 by use of an isoperibol solution-reaction calorimeter. Molar enthalpies of dissolution of Ba[d-C6H11O7]2·4H2O(s) at various molalities are measured at T=298.15K in the double-distilled water. According to the Pitzer theory, the molar enthalpy of dissolution of the title compound at infinite dilution is calculated to be ΔsHm∞=(49.901±1.212)kJ·mol−1. The values of relative apparent molar enthalpies (appH), relative partial molar enthalpies of the solvent (H¯1) and the compound (H¯2) at different molalities m/(mol·kg−1) are derived from the experimental values of the enthalpies of dissolution of the compound.