X-ray absorption studies of copper (II) mixed ligand complexes with ethylenediamine (en) as one of the ligands

X-ray K-absorption spectra of six biologically important copper (II) complexes having ethylenediamine (en) as primary ligand and nitrate, thio-cynate, perchlorate, bromide, chloride and sulphate as secondary ligands have been studied using a bent crystal 0.4 m Cauchois-type transmission spectrograph. Various parameters, e.g., chemical shift, energy position of the principal absorption maximum, effective nuclear charge and edge-width have been determined. The K-absorption edges have been found to split into two components, i.e., K1 and K2 in all of these complexes. All the complexes have been found to have copper in oxidation state +2. The relative ionic character of the complexes has also been determined and correlated with spectrochemical series.