XAFS Study of Benzimidazole Mixed Ligand Complexes of Copper.

X-ray absorption fine structure has been studied at the Cu K-edge in copper complexes having benzimidazole as primary ligand and chloride, bromide, nitrate, sulphate as secondary ligands. The spectra have been recorded on beamline BL-8 of Indus-2 synchrotron at RRCAT, Indore. From the X-ray absorption near edge structure (XANES) data, various X-ray absorption parameters, viz., shift of the edge, shift of the principal absorption maximum and edge-width have been obtained. The experimentally observed values of chemical shifts indicate that copper is in oxidation state +2 in the samples. The chemical shifts have also been used to determine effective nuclear charge on the central metal ion in the complexes. The first shell bond distances have been determined from the extended X-ray absorption fine structure (EXAFS) data by three different graphical methods, namely, Levy’s, Lytle’s and LSS methods. Fourier transforms of the normalized spectra have also been used to obtain bond lengths. The bond lengths determined from LSS method and that determined from the Fourier transformation method are in good agreement with each other. The present results obtained using synchrotron have been compared with those reported earlier using laboratory X-ray spectroscopic set-up employing X-ray tube. [ABSTRACT FROM AUTHOR]