SYNTHESIS, SPECTRAL CHARACTERIZATION AND STABILITY OF THE NEW ND (III) AND CO (II) HETEROMETALLIC COMPLEXES WITH AMINOPOLYCARBOXYLIC ACIDS

New heterometallic complexes of Nd(III) and Co(II) based on ethylenediaminetetraacetic and ethylenediaminedisuccinic acids have been synthesized. The complexes studied by electron absorption spectroscopy, IR-spectroscopy, and thermogravimetric analysis. The influence of a number of factors on the properties and structure of heteronuclear complexes is discussed. The spectral characteristics of homonuclear and heteronuclear complexes are compared. A theoretical analysis of the geometry of Co(II) and Nd(III) complexes with ethylenediaminesuccinic acid was carried out by the semi-empirical PM7 method. It has been shown that the f-d-complexes are of the folded type, in which the ligand-complexone realizes the maximum denticity to Nd(III), and the Co(II) coordination sphere is formed by bridging edta/edds carboxyl groups and intrasphere water molecules. The Co(II) coordination polyhedron corresponds to a distorted octahedron, and the Nd(III) coordination polyhedron corresponds to a one-capped square antiprism (C4v) with the coordination number Nd(III)=8. During study fixed that heterometallic complexes have the same structure in solutions and in the solid state.