Influence of Aryl-bonded Substituents on Complex Formation of Benzocrown Ethers with Alkali Metal Ions in Methanol and Acetone Solutions

Article abstract of DOI:10.1002/prac.19943360103

The influence of aryl-bonded substituents upon the complex formation of monobenzocrown ethers towards alkali metal ions in methanol and acetone solutions are investigated by using calorimetric and potentiometric titration.A different complexation behaviour of the ligands in acetone and methanol was found.In the case of the 1:1 complexation of Na⁺ a correlation between substituent effects and stability constants in acetone was noticed, however, the influence of substituents upon complex stability is weak.In methanol solutions no similar correlation could be established.During sandwich complexation of K⁺ in methanol, no significant substituent influences on K₁ and K₂ were observed.On the other hand, a considerable increase of ΔH₂ for both the electron accepting and electron releasing substituents was found, probably caused by changes in ligand-cation solvation due to the substituents.