DFT Studies on η⁶-Coronene-Cr(CO)₃ Complexes

Lemi Türker* and Selçuk Gümüş

Middle East Technical University, Department of Chemistry, 06531, Ankara, Turkey
* Corresponding author: E-mail: lturker@metu.edu.tr
Phone: +90 312 2103244; fax: +90 312 2103200

Abstract
Two types of Cr(CO)₃ complexes of coronene have been considered theoretically at the level of DFT (B3LYP/6- 31G(d)), in order to investigate some molecular orbital, electronic and thermodynamic properties. The effect of complexation on the stability and aromaticity of coronene has been investigated by NICS calculations. According to the results, both in the gas phase and in aqueous solution, B-type complex has been found to be more stable than the A-type, however, the energy difference is such that B to A conversion could be possible by means of haptotropic shift of the chromium moiety. The interaction energy of the B-type complex is greater then the A-type, supporting the stability of the former over the latter. NICS calculations indicated that aromaticity of the outer rings has been drastically decreased by complexation.

Keywords: Coronene, Cr(CO)₃ complexes, haptotropic shift, NICS, aromaticity