Aggregation Study on Lithiated Five-membered Heterocycles – Towards the Pentuple Ion
by Markus Granitzka
Date of Examination:2013-02-15
Date of issue:2014-01-30
Advisor:Prof. Dr. Dietmar Stalke
Referee:Prof. Dr. Dietmar Stalke
Referee:Prof. Dr. George M. Sheldrick
Referee:Dr. Heidrun Sowa
Referee:Prof. Dr. Thomas Waitz
Referee:Dr. Inke Siewert
Referee:Prof. Dr. Ulf Diederichsen
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Abstract
English
The main work of this thesis focuses on the elucidation of the aggregation of 2-thienyllithium, methyl-substituted 2-thienyllithium and 2-furyllithium in the solid state and in solution. The addition of an adequate donor base to lithium organics reduces their aggregation. Their solid-state structures is determined by single crystal X-ray diffraction experiments and their coordination behaviour in solution by means of multi nuclear NMR techniques. For many lithium organics the deaggregation proceeded by going from oligomers to monomers, via hexamers, tetramers and dimers. The investigations of the established aggregation ladder should take one step further by searching for yet unknown, however theoretically predicted, aggregates in between the established rungs of the ladder. The scope of the second part is the development of synthetic routes and structurally investigation on the coordination behavior of bis(2-thienyl)diethylamino-phosphane in late transition metal complexes using single crystal X-ray diffraction. The study will shine light on different coordination geometries by forming complexes with different metals, and it will be investigated if different metals coordinate selectively to the soft sulfur or phosphorus coordination site. Moreover, the transformation of bis(2-thienyl)diethylaminophosphane to the bis(2-thienyl)phosphane, a promising P,S-ligand, is another interest, and the effect of variation/elongation of the heterocyclic side arms shall be examined by challenging syntheses of heterocyclic substituted phosphanes.
Keywords: Lithium; Lithium organics; X-Ray; NMR; Phosphane; Aggregation