COORDINATION OF TRANSITION-METAL IONS BY CHELATING CATION-EXCHANGE RESINS - CO(II), NI(II) AND CU(II) COORDINATED BY THE IMINODIACETATE GROUP IN CHELEX-100

The interaction between the iminodiacetate group of the chelating ion-exchange resin Chelex-100 and Co(II), Ni(II) and Cu(II) has been studied with the aid of electronic spectra and EPR. It is concluded that the iminodiacetate functional group in Chelex-100 coordinates as a tridentate chelating ligand to these metal ions. The coordination polyhedron (distorted octahedral) is completed by either water molecules or by carboxylate oxygens from excess, neighbouring iminodiacetate groups, resulting in a chromophore [MO5N]. No evidence is found for species MO6 as suggested in earlier work whereas species MO4N2, like those observed in monomeric (M(iminodiacetate)2 chelates, are neither observed. © 1979.