Synthesis and characterization of low-valent actinide complexes with amidinates and related ligands
The oxidation state of four (i.e. M4+) is predominant particularly for the actinides thorium (Th), uranium (U), neptunium (Np) and plutonium (Pu) under reductive conditions, which could potentially occur in a nuclear waste repository. The migration behavior of actinides is significantly affected by the interaction with co-existing inorganic- and organic ligands. In order to investigate the fundamental properties of the interactions between actinides and the co-existing ligands, it is necessary to use model systems with some representative ligands and/or functional groups.
In this PhD project, the interactions of actinides Th, U, Np and Pu with amidinates (R-NH-C(R‘)=N-R) and their derivatives will be studied with a special focus on their lower-valent states (M(IV) and –(III)). Complexes of several transition metals including lanthanides with these ligands have already been synthesized1-2, whereas the relevant complexes with actinides are very limited3-5. The group of Prof. Roesky (Karlsruhe Institute of Technology, KIT) synthesized the ligands used in this thesis6. Hence, one of the main aims of this project is to synthesize the actinide complexes with the amidinate ligands and characterize the synthesized complexes with a variety of analytical methods like single-crystal x-ray diffraction. Syntheses are performed under inert conditions using Schlenk techniques and inert glove boxes. The complexes are characterized also in solution with different spectroscopic techniques including NMR, UV-Vis, IR and TRLFS. These experimental data will be further compared with quantum chemical calculations to obtain an comprehensive overview of the physical/chemical properties of these actinide complexes, such as their electronic nature.
This PhD project is financially supported by the BMBF project “FENABIUM”. (No. 02NUK046B)
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- Benndorf, P.; Preuß, C.; Roesky, P. W., Synthesis of Enantiomeric Pure Lithium and Potassium Benzamidinate Complexes. J. Organomet. Chem. 2011, 696 (6), 1150-1155.