Solid-liquid phase equilibrium and thermodynamic analysis of metal dithiolene complex: The case of zinc dibutyldithiocarbamate

Abstract

The structure and properties of Bis (dibutyldithiocarbamato) zinc (BZ) were investigated in both solution and solid phases. The single crystal structure of BZ is reported, and crystal packing and Hirshfeld surface analyses reveal the dominant hydrophobic interactions in the solid-state structure. The solution thermodynamic properties including solid-liquid equilibrium solubility and thermodynamic functions of mixing were determined in twelve solvents (methanol, ethanol, n-propanol, n-butanol, isopropanol, acetonitrile, n-hexane, n-heptane, cyclohexane, ethyl acetate, acetone and toluene). The equilibrium solubility data was measured by the gravimetric method at temperatures ranging from (283.15 to 323.15) K. The solubility of BZ in twelve solvents decreases in general as the polarity of solvent increases and basically follows the rule of “like dissolves like”. The solubility is monotonously rising with increasing temperature as expected in all solvents. Further, the statistical correlations were well performed by the modified Apelblat equation, λh equation and NRTL model, and the modified Apelblat equation achieves the best fitting results. Finally, thermodynamic functions of mixing (enthalpy, entropy, and Gibbs energy) were derived, and the results suggest a spontaneous and entropy-driven mixing process. The crystallographic and solubility data, correlated models, and derived thermodynamic functions provide thermodynamic fundamentals for separation and purification of BZ crystallization in industrial production.