Spectrochimica Acta Part A 56 (2000) 1653 – 1660 Spectroscopic properties and ligand field analysis of cis -diazido(1,4,8,11-tetraazacyclotetradecane)chromium(III) azide Jong-Ha Choi * Department of Chemistry, Andong National Uniersity, Andong 760 -749, South Korea Received 13 August 1999; accepted 6 January 2000 Abstract The emission and excitation spectra of cis -[Cr(cyclam)(N 3 ) 2 ](N 3 ) (cyclam =1,4,8,11-tetraazacyclotetradecane) taken at 77 K are reported. The infrared and visible spectra at room temperature are also measured. The vibrational intervals due to the electronic ground state are extracted from the far-infrared and emission spectra. The ten electronic bands due to spin-allowed and spin-forbidden transitions are assigned. Using the observed transitions, a ligand field analysis has been performed to determine the bonding property of azido group in the chromium(III) complex. It is found that azide ligand has weak - and -donor properties toward chromium(III) ion. The zero-phonon line in the excitation spectrum splits into two components by 249 cm -1 , and the large 2 E g splitting can be reproduced by the ligand field theory. © 2000 Elsevier Science B.V. All rights reserved. Keywords: Electronic transitions; AOM parameters of azide ligand; Chromium(III) www.elsevier.nl/locate/saa 1. Introduction The synthesis, hydrolysis, spectral properties, photobehavior and X-ray crystal structure of the cis -diacidochromium(III) complexes containing the tetradentate marcrocyclic ligand cyclam (1,4,8,11-tetraazacyclotetradecane) have been ex- tensively studied [1 – 10]. We also described the vibrational and electronic energy levels based on the emission, far-infrared and electronic spectra [11–15]. The application of electronic spec- troscopy to chromium(III) complexes promises to provide information concerning metal-ligand bonding properties as well as molecular geometry. With the use of excitation or absorption spec- troscopy the narrow intraconfigurational transi- tions due to the spin-forbidden in chromium(III) system can be located with a precision two orders of magnitude greater than can the broad spin-al- lowed bands. In particular, the splittings of sharp- line electronic transitions are very sensitive to the exact bond angles around the metal. Thus it is possible to extract structural information from the electronic spectroscopy without a full X-ray struc- ture determination [16,17]. * Tel.: +82-54-8505458; fax: +82-54-8411627. E-mail address: jhchoi@andong.ac.kr (J.-H. Choi) 1386-1425/00/$ - see front matter © 2000 Elsevier Science B.V. All rights reserved. PII:S1386-1425(00)00221-3