ESR SPECTROSCOPY OF COPPER(II) COMPLEXES WITH AZA-CONTAINING AND THIA-CONTAINING CROWN-ETHERS

Six copper(II) chloride complexes with crown ethers containing besides oxygen also nitrogen or sulfur atoms in 15- or 18-membered cycle were studied by ESR and electron absorption spectroscopies. The g and HFI tenser components determined by spectral simulation indicate rhombic s ymmetry and localization of an unpaired electron on the d(xy) orbital for all the complexes. The unpaired electron fractions on sigma- and p i-type metal ion and ligand AO were estimated from ESR and absorption spectra using LCAO MO method. Both sigma- and pi-type bond covalences were shown to be greater in these complexes compared to only oxygen-co ntaining crown ether complexes. The temperature dependence of g and A components in some complexes may be due to conformational changes.