N2 Splitting and Functionalization in the Coordination Sphere of Tungsten
by Bastian Schluschaß
Date of Examination:2020-09-22
Date of issue:2020-12-02
Advisor:Prof. Dr. Sven Schneider
Referee:Prof. Dr. Sven Schneider
Referee:Prof. Dr. Franc Meyer
Referee:Prof. Dr. Manuel Alcarazo
Referee:Prof. Dr. Dirk Schwarzer
Referee:Dr. Michael John
Referee:Dr. Christian Sindlinger
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Abstract
English
The splitting and functionalization of N2 remains one of the most challenging reactions in coordination chemistry. In this thesis a series of four isostructural end-on N2 bridged ditungsten-PNP-pincer complexes are synthesized and thoroughly characterized. Furthermore, their properties with respect to NN-bond scission are investigated. In this context, it is shown that proton induced N2-splitting competes with proton-reduction and that the selectivity is controlled by the respective acid and reaction temperature. In an other example, N2-cleavage is found to be in equilibrium with reverse nitride coupling. Interestingly, the reaction can also be driven photolytically, which was studied extensively using transient spectroscopy combined with DFT-analysis. The so-formed nitride species is functionalized with CO in an intramolecular mechanism to give cyanate, which can be liberated to close a synthetic cycle.
Keywords: Nitrogen Fixation; Coordination Chemistry; Photochemistry; Tungsten Pincer Complexes; Nitride CO coupling