Spectroscopic and ligand-field properties of [L-prolylglycinato][di(3-aminopropyl)amine]chromium(III) perchlorate.

The mixed ligand complex [Cr(L-progly)(dpt)]ClO4 [H2progly = prolylglycine, dpt = di(3-aminopropyl)amine] has been prepared, and its geometric structure was discussed on the basis of electronic absorption and IR spectral data. The emission and excitation spectra taken at 77 K were also reported. The 12 electronic bands due to spin-allowed and spin-forbidden transitions were assigned. Using the electronic transitions, a ligand-field optimization has been performed to determine the metal-ligand bonding properties for the coordinated atoms. We confirmed that the peptide nitrogen of prolylglycinate has moderate strong sigma- and weak pi-donor properties toward chromium(III) ion.