Ligand field properties of histidine on the sharp-line excitation spectrum of trans(imidazole)-bis( L-histidinato- O, N, N′)chromium( III) nitrate

Abstract

Ligand field calculations have been performd based on the data from the absorption and low temperature sharp-line excitation spectra of trans(imidazole)-[Cr( L-his) 2]NO 3. The angular overlap parameters determined for imidazole nitrogen are 6233 cm −1 for e σNim and −549 cm −1 for e πNim . This indicates that the imidazole nitrogen is a weak σ-donor and its π-interaction can be interpreted by back-donation to the electron withdrawing empty molecular orbitals on the imidazole nitrogen.