POTENTIOMETRIC AND PROTON NMR-STUDIES ON ZINC(II)-AMINOHYDROXAMIC ACIDS

Potentiometric and NMR studies on Zn(II) ions interaction with alaninehydroxamic acid, leucinehydroxamic acid, sarcosinehydroxamic acid, and histidinehydroxamic acid have shown that metal ion initiates its coordination with two oxygens of the hydroxamic group. The deprotonation of the amino group leads to formation of dinuclear species Zn2L3 in the case of the three former ligands and the tridentate coordination involving side-chain imidazole nitrogen in the case of histidine derivative. The formed complexes are very stable although in very basic solutions the hydroxy-species may be formed.