28 août 2024
9h00
Conversion of Borohydrides in Reactions with BH3 and CO2 by Jian WANG
Pour l'obtention du grade académique de doctorat en Sciences
Dodecaborate anion (B₁₂H₁₂²⁻) is an icosahedral cluster consisting of twelve boron and twelve hydrogen atoms, forming a highly symmetric and stable polyhedral structure. This anion has attracted significant interest in both academic research and in practical due to its unique properties, such as high thermal stability, chemical inertness, and the potential to form various derivatives through substitution reactions. Unlike typical boranes, which are often reactive and less stable, B₁₂H₁₂²⁻ stands out for its exceptional robustness, making it an ideal candidate for applications ranging from medicine to materials science. The objective of this thesis was to develop novel, simple, and efficient methods for synthesizing B₁₂H₁₂²⁻ salts using cost-effective and manageable borane precursors, rather than traditional methods that rely on B₂H₆ and B₁₀H₁₄. To achieve this, we employed DMS∙BH₃ and borohydrides as precursors, successfully obtaining a series of high-purity B₁₂H₁₂²⁻ compounds through simple solvothermal synthesis. Our research highlights the critical role of factors such as temperature, solvent choice, reaction duration, and the enclosed system in synthesizing high-purity solvated metal-B₁₂H₁₂ compounds. Following the synthesis, we investigated the desolvation processes and proposed solvent exchange as a more efficient alternative to conventional cation exchange methods for obtaining anhydrous metal-B₁₂H₁₂ salts. Furthermore, our experimental work has outlined a stepwise mechanism for the formation of B₁₂H₁₂²⁻, providing valuable insights into the synthesis process. Notably, the relatively straightforward reaction setups employed in this work led to the discovery of entirely new and highly favorable conditions for the high-purity synthesis of this class of materials.
Jury members :
- Prof. Yaroslav Filinchuk (UCLouvain), supervisor
- Prof. Eric Gaigneaux (UCLouvain), chairperson
- Prof. Michael Singleton (UCLouvain) , secretary
- Prof. Tom Leyssens (UCLouvain)
- Prof. Hai-Wen Li (HGMRI, China)
- Prof. Torben René Jensen (AU, Denmark)
The public defense of Jian WANG will be conducted solely by videoconference (Meeting ID: 322 066 723 737 - Passcode: 2jaS9s)