A comparative analysis of the structures of copper(II) and nickel(II) chelate complexes with N-substituted 2-aminoethanols, 3-aminopropan- 1 -ols, glycines and beta-alanines is performed. It is shown that tetradentate ligands based on 3-aminopropan- 1 -ol and P-alanine, sterically hindered 2-aminoethanol derivatives and tridentate enamino ketone derivatives tend to form oligonuclear copper(II) and nickel(II) complexes. Glycine derivatives do not provide the formation of oligonuclear copper(II) and nickel(II) complexes. The magnetic properties of a number of polynuclear complexes are compared.