Abstract: The choice ofsuitable ligand platforms is crucial to organometallic coordination chemistry
and homogeneous catalysis. Among the various ligand platforms available, pincer ligands
offer a convenient route to manipulate the properties of the resulting complexes. The
pincer chemistry of rhodium has attracted attention for over 40 years, and Rh complexes
are dominated by Rh(I) and Rh(III) low-spin states, thus they are more predictable than
other paramagnetic species. Compared to other pincer ligand platforms, pyridine-based
pincer complexes are particularly attractive as they exhibit diverse reactivities. Our group
realized a new class of the PN3
(P) pincer system, with altered the unique catalytic
performances, thermodynamic and kinetic properties due to their pseudo-dearomatized
nature.
In Chapter 2, selective carbonylation of benzene to benzaldehyde using a phosphorus nitrogen PN3P Rh(I) complex was realized. The PN3P Rh pincer chloride complex
cPePN3PRhCl was capable of activating C−H bond of benzene to give the phenyl complex
cPePN3PRh(C6H5) using KN(SiMe3)2 as a base. Furthermore, the benzoyl complex
cPePN3PRh(CO)(C6H5) was obtained by treating a benzene solution of cPePN3PRh(C6H5) with
CO gas. In dilute HCl, a high yield of 90% benzaldehyde was formed with regeneration of
the cPePN3PRhCl. This is the first example of selective carbonylation of benzene into
benzaldehyde accomplished by directly inserting CO without irradiation.
In Chapter 3, the ligand-centered reactivity of a pseudo-dearomatized PN3P
*rhodium complex towards molecular oxygen wasrealized. For the dearomatized rhodium carbonyl
complex (tBuPN3P*RhCO), one of the C−H bonds of the pseudo-dearomatized pyridine ring
was oxidized by O2 to create an α, β-unsaturated carbonyl functionality. Moreover, the
resulting metal complex with the post-modified PN3P ligand could react with thiophenol
and 4-methylaniline to afford the corresponding oxidative Michael addition products.
In Chapter 4, to further explore the ligand-centered reactivity of tBuPN3P
*RhCO, a series of second-generation diimine-amido PN3P-pincer carbonyl complexes were synthesized
by reaction of tBuPN3P*RhCO and various alkyl/benzyl halides via a post-modification
strategy, and these complexes were well characterized by NMR, HRMS, FT-IR, and single
crystal diffraction. Moreover, a plausible mechanism for the formation of 2nd
-generation PN3P complexes was proposed
| Identifer | oai:union.ndltd.org:kaust.edu.sa/oai:repository.kaust.edu.sa:10754/670974 |
| Date | 08 1900 |
| Creators | Zhou, Chunhui |
| Contributors | Huang, Kuo-Wei, Physical Science and Engineering (PSE) Division, Yu, Han, Lai, Zhiping, Wang, Shaowu |
| Source Sets | King Abdullah University of Science and Technology |
| Language | English |
| Detected Language | English |
| Type | Dissertation |
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