Exploring Transient Dialumene and Diazido-Dialane: Low Oxidation State Aluminium Chemistry based on a Hybrid Ligand

by Xiaobai Wang
Doctoral thesis
Date of Examination:2025-02-14
Date of issue:2025-06-12
Advisor:Prof. Dr. Dietmar Stalke
Referee:Prof. Dr. Franc Meyer
Referee:Prof. Dr. Manuel Alcarazo
Referee:Prof. Dr. Malte Jun.-Fischer
Referee:Prof. Dr. Daniel Obenchain
Referee:PD Dr. Michael John
Persistent Address: http://dx.doi.org/10.53846/goediss-11322

 

 

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Abstract

English

This thesis focuses on the exploration and development of the hybrid NacNac-Box-akin ligand, DippNac-Indole (DNI), and its application in stabilizing low oxidation state aluminium complexes. The study is structured to advance the understanding of the DNI ligand, starting with its design, potential to provide stability, control reactivity, and influence on the coordination chemistry of aluminium. The first part of this study focuses on the conceptual framework behind the synthesis of the DNI ligand. The design strategy is centered around combining the advantages of both bis(heterocyclo)methane (Box) ligands and β-diketiminate (BDI) ligands. This hybrid approach aims to leverage the rigid indolyl moiety of the Box ligand, which provides structural stability and limits deformation, while also incorporating the steric control provided by the Dipp substituents of the BDI ligand. Following this, the thesis will explore the synthetic methods used to integrate the DNI ligand into aluminium complexes. It will examine how DNI helps to stabilize low oxidation state aluminium complexes, which are usually highly reactive and unstable. The goal is to add to the existing body of knowledge by showcasing how DNI can effectively stabilize aluminium in oxidation states like Al(I) and Al(II), which are typically transient and challenging to handle. The thesis will investigate how the unique properties of the DNI ligand enable these aluminium complexes to engage in bond activation and explore the reactivity of these stabilized aluminium complexes, particularly their ability to activate small molecules and their possible application in catalysis. Subsequently, this thesis introduces new avenues in low-oxidation-state aluminium-azide chemistry. The alumination of azides was investigated using a DNI ligand-supported dialane platform, uncovering previously unobserved reactivity with diverse substituted organic azides (TMSN3, BnN3, 1-AdN3, DippN3). This approach reveals novel insights into the behavior and bonding in aluminium-azide interactions with the help of single-crystal X-ray diffraction and NMR spectroscopy. The final summary will also explore the prospects of DNI and DNI-based dialane ligands in the context of general aluminium chemistry, discussing their potential reactivity, ability to activate small molecules, and future applications in catalysis.
Keywords: Low Oxidation State Aluminium; Hybrid Ligand; Dialumene; Diazido-Dialane; Inorganic Chemistry
 
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