Sombat Ketrat – Projects
Quantum chemical investigation of the haptotropic rearrangement of Cr(CO)3 templates on polycyclic aromatic systems.
Chromium-arene complexes are widely used in modern organic synthesis. The Cr(CO)3 fragment can act as a template in the subsequent reactions of the complex, which proceed with enhanced stereoselectivly and regioselectivly. The metal-ligand fragment can migrate along the π-system of the arene ligand, i.e., perform a so-called haptotropic rearrangement. Under appropriate conditions it was found to be possible to make the Cr(CO)3 fragment move reversibly, i.e., to construct a molecular switch.
The goal of this project is the quantum chemical investigation of the haptotropic rearrangement of metal-containing templates (CrL3, with L = CO, PR3) on functionalized multi-ring aromatic π-electron systems. We intend to clarify the reaction mechanism, i.e., especially we aim to determine the local minima on the energy hypersurface as well as the corresponding saddle points of the connecting lowest-energy reaction pathways. The calculations should indicate how electronic and steric effects, e.g., resulting from suitable substituents on the aromatic system or the CrL3-template, can be used for a controlled induction and steering of the haptotropic rearrangement. We also plan to investigate the reversible positioning of the CrL3-template by means of changes of the external conditions and parameters (e.g., pH-value, oxidation or reduction of ligands, electronic excitations). Finally calculations on possible follow-up reactions of the CrL3-template complexes will be studied. The calculations will be performed mainly with first-principles methods, i.e., density functional theory and, for verification of energy-differences, single-point MP2 and/or CCSD(T) approaches. If necessary solvent effects will also be included. The properties of interesting educts, products and intermediates will be calculated and bonding properties will be analyzed.
This project is funded by the German Science Foundation () in the framework of the (). The theoretical work described above is carried out in close collaboration with the corresponding experimental investigations in the group of ().
- Theoretical study of haptotropic rearrangements of chromium tricarbonyl complexes with arene system. S. Ketrat and M. Dolg, in preparation.