Complex Formation of Some Anilinium Ion Derivatives with 18-Crown-6, 1,10-diaza-18-crown-6 and Cryptand C222 in Acetonitrile, Dimethylformamide and their 1 : 1 Mixture

The complexation reactions between the protonated salts of aniline, o-hydroxy aniline, o-amino aniline and 2,3-benzo aniline (-naphthylamine) and macrocyclic ligands 18-crown-6,1,10-diaza-18-crown-6 and cryptand C222 have been studied conductometrically in acetonitrile, dimethylformamide and their 1 : 1 (mol–mol) mixture at 25 °C. Formation constants of the resulting 1 : 1 complexes were determined from the computer fitting of the molar conductance-mole ratio data. In all cases studied, the stability of the complexes decreases in the order C222 > 1,10-diaza-18-crown-6 > 18-crown-6. There is also an inverse relationship between the stabilities of the complexes and the Gutmann donor number of the solvents. It was found that, in the aromatic anilinium series used, increasing the bulkiness of the organic substituent in the ortho position results in a loss of complex stability.