COMPLEXING ABILITY OF MONENSIN ANION FOR ALKALI-METAL CATIONS IN BINARY-MIXTURES OF DIPOLAR APROTIC-SOLVENTS

Cyclic voltammetric studies have been carried out on monensin anion co mplexes with the alkali metal cations in binary mixtures of dimethylsu lfoxide with acetonitrile, acetone and hexamethylphosphoric triamide, respectively. The log K-s values obtained for the complexity constants can be well described by empirical relation log K-s = alpha D-N + bet a, where D-N stands for the effective donor number of a given solvent mixture and alpha and beta mark the regression coefficients. This resu lt is in agreement with the predominant role of cation solvation. The complexes show a sharp stability maximum for the Na+ complex in all me dia under investigation.