Beaufils, Alicia (2025). Synthesis and Catalytic Application of Complexes with Pyridylidene Amide Ligands in Transfer Hydrogenation. (Thesis). Universität Bern, Bern
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Abstract
This thesis aimed to expand the family of coordinatively unsaturated donor-flexible complexes to better comprehend the intrinsic stability of such species, often described as entry points or reaction intermediates in numerous catalytic cycles. N,N’-bidentate donor-flexible ligands have shown to be useful systems for this purpose, and in combination with the evidenced flexibility of pyridylidene amide (PYA), we aimed to develop N,N’-PYA ruthenium complexes and explore their activity in catalytic transfer hydrogenation. Chapter II presented the synthetic protocol to obtain the model coordinatively unsaturated N,N’-PYA ruthenium complex. Reactivity studies with a series of two-electron donor ligands demonstrated the flexibility of the ligand scaffold for the stabilization of both 16- and 18-electron species. The accessibility of the ruthenium center is further evidenced by the excellent performance of the complex in the catalytic transfer hydrogenation of ketones using ethanol. Chapter III further investigated the catalytic application of this complex in transfer hydrogenation reactions. It presented the first example of chemoselective room-temperature transfer hydrogenation of C=C bond in a,b-unsaturated carbonyls using ethanol to yield a variety of functionalized products. Preliminary mechanistic studies showed the potential implication of a ruthenium-alkoxide complex as an initially formed species. Chapter IV focused on further improvement of catalytic performances in transfer hydrogenation using the synthesis of a second generation of coordinatively unsaturated N,N’-PYA ruthenium complexes. Modulation of the ligand scaffold enhanced the selectivity in C=C bond transfer hydrogenation of a,b-unsaturated ketones, with significantly less over-hydrogenation of the C=O bond over time.
| Item Type: | Thesis |
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| Granting Institution: | Faculty of Science, University of Bern |
| Dissertation Type: | Single |
| Date of Defense: | 27 March 2025 |
| Subjects: | 500 Science > 540 Chemistry |
| Institute / Center: | 08 Faculty of Science > Department of Chemistry, Biochemistry and Pharmaceutical Sciences (DCBP) |
| Depositing User: | Alicia Beaufils |
| Date Deposited: | 13 Jan 2026 16:36 |
| Last Modified: | 13 Jan 2026 16:36 |
| URI: | https://boristheses.unibe.ch/id/eprint/5980 |
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