Ternary complexes of some bivalent metal ions with (trans-1,2-cyclohexylenedinitrilo)tetra-acetic acid and indole-3-butyric acid

Abstract

Formation constants of ternary complexes with (trans-1,2,-cyclohexylenedinitrilo)tetra-acetic acid (CDTA) as primary ligand and indole-3-butyric acid (IBA) as secondary ligand with metal ions Mn(II), Fe(II), Co(II), Ni(II), Cu(II), and Zn(II) have been determined by Irving-Rossotti pH titration technique in 50% (v/v) aqueous methanol at (298 ± 1) K and fixed ionic strength of μ = 0.1 M (NaClO 4). Formation constants of binary complexes have also been determined under identical conditions. The order of stabilities in terms of metal ions is Mn(II) < Fe(II) < Co(II) < Ni(II) < Cu(II) > Zn(II) for binary complexes and Mn(II) < Fe(II) < Co(II) > Ni(II) < Cu(II) > Zn(II) for ternary complexes.