The application of N-heterocyclic carbenes (NHCs) in organic and organometallic chemistry has been well-established. The utilization of Zr(NMe2)4 for transmetallation has facilitated the synthesis of CCC-NHC pincer transition metal complexes since 2005 by our group, including Fe, Co, Rh, Ir, Ni, and Pt. However, there have been no reports on the synthesis, characterization, and application of CCC-NHC pincer complexes involving Re and Mn to date. This dissertation aims to address this gap by discussing the synthesis and catalytic activities of CCC-NHC pincer Re and Mn complexes in crossed-coupling reactions. Chapter II will focus on the synthesis of the CCC-NHC pincer Re complex. The synthesis involved transmetallation with CCC-NHC pincer Zr complex using Re(CO)5Cl. The Re complex was characterized by 1H and 13C NMR spectroscopy, mass spectroscopy and its structure was determined by X-ray crystallographic methods. Catalytic activities of Re complex were demonstrated through borrowing hydrogen reactions for the crossed-coupling between ketones and primary alcohols, yielding α-alkylated ketones with water as the only by-product. The borrowing hydrogen reaction improved the economic efficiency when it did not require the good leaving group that conversed from primary alcohols. A wide range of substrates yielded yields ranging from 53% to 92%. Chapter III willdiscuss the expanded application of the Re complex, including borrowing hydrogen reactions for coupling between primary and secondary alcohols, as well as one-pot synthesis of quinolines via dehydrogenative/oxidative cyclization reactions. Control experiments support the proposed catalytic cycle of borrowing hydrogen reactions by the Re complex. In Chapter IV, the synthesis and catalytic activities of CCC-NHC pincer Mn complex are examined. The proposed structure of the Mn complex was supported by NMR spectroscopy, mass spectroscopy, and single X-ray diffraction. The Mn complex demonstrates catalytic activities through borrowing hydrogen and dehydrogenative cyclization, yielding α-alkylated ketones, 2-oxindole derivatives, and quinolines. The control experiments were set up and the proposed mechanism of Mn complex for borrowing hydrogen reaction were consistent with Re complex.
| Identifer | oai:union.ndltd.org:MSSTATE/oai:scholarsjunction.msstate.edu:td-7265 |
| Date | 13 August 2024 |
| Creators | Pham, Huy Hoang |
| Publisher | Scholars Junction |
| Source Sets | Mississippi State University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Theses and Dissertations |
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