ESR SPECTRA OF THE SQUARE PLANAR COPPER(II) COMPLEXES WITH VARIOUS N₄-MACROCYCLIC LIGANDS

Abstract

The ESR parameters were determined for copper(II) complexes with various 14-, 15- and 16-membered N₄-macrocyclic ligands. Of these ESR parameters g^‖ has the most simple relation to the covalency of the coordination bonds in the present compounds, i.e., the smaller the g^‖ value the larger the covalency. The order of covalencies derived from the g^‖ values nicely matches with that supposed from the size of macrocyclic rings and the charge of the ligands. The approach to the estimation of covalency of the coordination bonds by use of copper hyperfine coupling constant was examined, but it was found that this approach gives rather unreliable results for the present compounds.