Diploma- & Master thesis
Synthesis and Characterisation of U(IV) complexes with N-heterocyclic carbenes
Dr. Juliane März
Chemistry of the f-elements
Carbenes are divalent neutral carbon derivates, where only six valence electrons exist. The carbene centre can be in a singlet- or triplet-groundstate, depending on the substituents on the carbon and their influence on the carbene orbitals. N-heterocyclic unsaturated five-membered derivates are very stable, because of the 6π-electronic stabilization and two nitrogen atoms directly neighbouring the carbene centre. These molecules exhibit exclusively soft σ-donor properties and thus are an interesting class of ligands for actinides. Because the coordination chemistry of tetravalent actinides is underdeveloped, there still has to be much work done. For example, the first U(IV)complex was not published until 2004 by Evans.1 Especially the binding motif to soft donor atoms is very little investigated. The goal of this work is to synthesise complexes like 10 of tetravalent Uranium with the NHCs 1,3-Diisopropylimidazol-2-yliden 9a and 1,3-Bis(2,6-diisopropylphenyl)imidazol-2-yliden 9b. The characterization shell include both, investigations in solution via NMR and uv-vis-spectroscopy, and characterisation in solid phase via single crystal X-ray diffractometry and infrared-spectroscopy. Theoretical investigations like frequency analysis and structure optimisation shell complete the experimental data.
- W. J. Evans, S. A. Kozimor, J. W. Ziller, Polyhedron 2004, 23, 2689–2694.