Thermodynamic study of the binding of hexathia-18-crown-6-tetraone with some transition and heavy metal ions in dimethyl sulfoxide solution

Abstract

A conductance study of the interaction between CO²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Pb²⁺ and Hg²⁺ ions with hexathia-18-crown-6-tetraone in dimethyl sulfoxide solution has been carried out at various temperatures. Formation constants of the resulting 1:1 complexes were determined from the molar conductance–mole ratio data and found to vary in the order Hg²⁺>Pb²⁺>Cd²⁺>Cu²⁺>Ni²⁺>Co²⁺>Zn²⁺. The enthalpy and entropy of complexation were determined from the temperature dependence of the formation constants. All complexes formed were enthalpy stabilized but entropy destabilized.