Kinetics and equilibria of dialkylthallium(III) complexes of some thiacrown-ethers in acetonitrile

The rate constants k₁ and activation enthalpies H of complex formation of dialkylthallium(III) perchlorates with some thia-18-crown-6 ethers were determined in acetonitrile. The equilibrium constants K were also obtained. More symmertrical thiacrown-ethers give smaller k₁ and K values, which are mainly regulated by the entropy term rather than the enthalpy term. Diethylthallium(III) ion gives smaller rate constants than those of dimethylthallium(III) ion. The K values of these complexes decrease as oxygen of the 18-crown-6 was replaced by sulfur.