Covalent bonding in copper(II) complexes with hetarylformazans according to EPR spectra

Covalent bonding in a number of copper(II) complexes with hetarylformazans that have pseudotetrahedral or square-planar symmetry of the nearest metal environment was analyzed from EPR spectra. The dependence of the unpaired electron delocalization on the pseudotetrahedral distortion of the coordination polyhedron was determined. A change in the Zeeman coupling parameters was interpreted. Various contributions to the components of the hyperfine coupling (HFC) and ligand hyperfine coupling (LHFC) tensors were calculated. pd-Mixing of the AO of the copper ion was found to have a slight effect on the HFC parameters. In the components of the LHFC tensor, the contribution from isotronic LHFC is decisive.