As an extension of the previous work on the post-modification strategy of pyridine-based PN3P group 10 metal complexes, the triazine-based PN3P pincer ligands incorporating nickel complexes, Me-Et-PN3PNiCl, and Me-Et-PN3PNiI, were synthesized and characterized. The solid state structures suggest that the N-donor atom of triazine-based PN3P ligands have more electron donating than the pyridine-based PNP pincer ligands.
A new non-symmetric PONNP pincer ligand system was developed to: (1) give more parameters for electronic and steric properties (2) to block the influence of acidic proton. However, the unstable metal-hydride complexes indicate the degradable O–P bond or N–P bond of the PONNP ligand. Treating the three ligands, including tert-butyl, phenyl, and cyclopentyl substituents with NiCl2(DME) individually all resulted in the production of [(PtBuONNPtBu)NiCl]+Cl-. It suggests that both O‒P and N‒P can cleave and rearrange during the complexation. The solvent effect and time tracing experiments demonstrated that the O‒P and N‒P bond rearrangement occurs after forming the nickel complex. The finding of [(ONNPtBu)NiCl]22+(Cl-)2 indicates the weakness of the O‒P bond, suggesting the degradation of an oxygen-phosphorus bond may be the initial step of substituents rearrangement.
To ensure the ligand-centered reactivity of (PtBuONNPtBu)*NiCl, a nickel-silver bimetallic complex, [(PtBuONNPtBu)*NiCl]2[AgOTf]2, was produced. In contrast to pyridine-based PN3P*NiH, there are two active sites of [(PtBuONNPtBu)*NiCl]2[AgOTf]2, the N atoms on the imine arm and pyrimidine ring. The solid-structure of the acid-base adduct compound, {[(PtBuONNPtBu)*NiCl][B(C6F5)3], demonstrates that the nitrogen atom on the pyrimidine ring is a better active site than the imine arm because of the steric effect. The molecular structures of [(PtBuONNPtBu)*NiCl]2[AgOTf]2 and {[(PtBuONNPtBu)*NiCl][B(C6F5)3] exhibit that the pyrimidine ring of [(PtBuONNPtBu)*NiCl]2[AgOTf]2 tends to be an aromatic zwitterionic form. The ligand backbone of {[(PtBuONNPtBu)*NiCl][B(C6F5)3] favors the dearomatized form.
| Identifer | oai:union.ndltd.org:kaust.edu.sa/oai:repository.kaust.edu.sa:10754/668891 |
| Date | 03 1900 |
| Creators | Huang, Mei-Hui |
| Contributors | Huang, Kuo-Wei, Physical Science and Engineering (PSE) Division, Mohammed, Omar F., Tung, Vincent, Guan, Hairong |
| Source Sets | King Abdullah University of Science and Technology |
| Language | English |
| Detected Language | English |
| Type | Dissertation |
| Rights | 2022-04-22, At the time of archiving, the student author of this dissertation opted to temporarily restrict access to it. The full text of this dissertation became available to the public after the expiration of the embargo on 2022-04-22. |
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