Potentiometric investigation of Schiff base equilibria involving salicylaldehyde and tridentate α-aminoacids with Cu(II), Ni(II) and Zn(II) in aqueous medium

摘要

Potentiometric determination of equilibrium constants and species distribution of Schiff base complexes, in aqueous solution, involving salicylaldehyde (A) and tridentate α-amino acids (B) (L-threonine, L-glutamine and L-glutamic acid) with metal ions Cu(II), Ni(II) and Zn(II) (M) indicates preference for the formation of Schiff base complexes rather than the ligands binding as such to the metal ions. Binary stability constants follow the Irving-Williams order: Cu(II) > Ni(II) > Zn(II), The influence of additional coordination sites such as -OH, -CONH_2 and -COOH in the formation of ternary complexes is also discussed.