SPECTROSCOPIC CHARACTERIZATION OF SOME Cu(II) COMPLEXES

摘要

3-hydroxy-4-methoxy benzaldehyde semicarbazone (HMBS) is a biologically active compound which has several potential donor sites. This compound has been used for complexation with Cu(II) ions to synthesize complexes of general formula [Cu(HMBS)_2X_2] where X is Cl~-, NO_3~- and CH_3COO~-. Cu(II) is a d~9 system for which ~2D term is generated. Under Oh symmetry, this term splits into ~2E_g and ~2T_(2g). the ground term ~2E_g is doubly degenerate and hence suffers strong Jahn- Teller effect and accordingly the further splitting of terms occur to lower the symmetry from perfect O_h. Here, the ligand occupies four planar positions while the two axial positions have been varied by using different ions like Cl~-, NO_3~- and CH_3COO~-. These variations on the axial positions also add to the distortion in O_h symmetry. Under strong distortion, the electronic spectral band splits into multiplets exhibiting tetragonal distortion in complexes. The extent of distortion has been derived by the derivation of the two radial parameters D_s and D_t from electronic spectral bands. The ESR spectra of complexes reveal the real position of the only unpaired electron of the d~9 system in complexes.