UV–Vis absorption study of some tetragonal chromium (III) complexes

A UV–Vis absorption study was performed in order to elucidate the electronic energy levels of three tetragonal chromium (III) complexes, namely trans-[Cr(en)2(CN)2]ClO4, trans-[Cr(cyclam)(CN)2]ClO4, and trans-[Cr(NH3)4(CN)2]ClO4. The absorption spectra of the preceding complexes have been analyzed via Gaussian analysis to locate the quartet band maxima of the tetragonal components. The deconvoluted band maxima were then fitted with the tetragonal energy matrices of d3 configuration with full configuration interaction, neglecting spin–orbit interaction. The ligand field parameters Dq, Dt, and Ds along with the electron correlation parameters have been extracted via the fitting procedure. The significance of these parameters and the translated angular overlap model parameters has been discussed. We have also uncovered in the spectrum of the ethylenediamine complex the low intensity doublet absorption bands and a high intensity charge transfer band which have been tentatively assigned.