Journal of Photosciences

Electronic Spectroscopy and Ligand Field Analysis of cis-[Cr(cycb)Cl2]Cl

Volume 11(2004), 19-23 page

ÀúÀÚ: Jong-Ha Choi, In-Gyung Oh, Subodh Kumar and Keon Sang Ryoo

   11-1-19.pdf (201.9K)

Keywords: Chromium(III)  Electronic transitions  AOM parameters, Ligand field properties


The sharp-line absorption spectrum of microcrystalline samples of cis-[Cr(cycb)Cl2]Cl (cycb = rac-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane) has been measured between 13000 and 16000 cm-1 at temperatures down to 5K. The 77K emission and excitation spectra, and 298 K infrared and visible absorption spectra have also been measured. The nine electronic bands due to spin-allowed and spin-forbidden transitions were assigned. Using the observed transitions, a ligand field analysis has been performed to probe the ligand field properties of coordinated atoms in the title chromium(III) complex. The zero-phonon line in the sharp-line absorption spectrum splits into two components by 240 cm-1, and the large 2Eg splitting can be reproduced by the modern ligand field theory. It is confirmed that nitrogen atoms of the macrocyclic cycb ligand have a strong ¥ò-donor character, but chloride ligand has weak ¥ò- and ¥ð-donor properties toward chromium(III) ion.