Please use this identifier to cite or link to this item: http://scholarbank.nus.edu.sg/handle/10635/17061
Title: SYNTHESIS, STRUCTURE AND CATALYTIC APPLICATION OF NOVEL CARBENE COMPLEXES WITH BENZOTHIAZOLIN-2-YLIDENE LIGANDS
Authors: YEN SWEE KUAN
Keywords: Benzothiazolin-2-ylidene, N,S-Heterocyclic Carbene Complex, Monocarbene, Biscarbene, Mononuclear, Dinuclear, Mix-NSHC-ligand complexes
Issue Date: 28-Jul-2009
Source: YEN SWEE KUAN (2009-07-28). SYNTHESIS, STRUCTURE AND CATALYTIC APPLICATION OF NOVEL CARBENE COMPLEXES WITH BENZOTHIAZOLIN-2-YLIDENE LIGANDS. ScholarBank@NUS Repository.
Abstract: N,S-heterocyclic carbene Pd(II) complexes and their catalytic activity were studied. A range of monocarbene, biscarbene and mononuclear, dinuclear Pd(II)-NSHC have been synthesized. This work was carried out with the objective of preparing new transition metal complexes containing the NSHC ligand and understanding of their formation. The solvent-free synthesis of benzothiazolium salts (carbene precursors) is discussed. The synthesis of bis-[PdBr2(NSHC)2] complex and dinuclear [PdBr2(NSHC)]2 complex which were prepared in CH3CN and DMSO respectively is presented. Trans-[PdBr2(NSHC)(Sol)] (Sol = CH3CN, and DMF) were thus obtained when the dinuclear Pd(II) was introduced in to these coordinating solvents. Two major compounds, cis- and trans- bis-[PdBr2(NSHC)2] complexes and two minor monocarbene complexes were obtained from an one pot reaction in CH3CN. Salt-metathesis of cis-[PdBr2(NSHC)2] with AgO2CCF3 afforded the mixed dicarboxylato-bis(carbene). These complexes were investigated as catalysts in Mizoroki-Heck and Suzuki-Miyaura coupling reactions. The synthesis and structural characterization of a series of mixed-NSHC-ligand complexes with phosphine, aromatic N-heterocycles, pyridyl and azole ligands are also discussed. Cis-[PdBr2(NSHC)(PR3)] complexes were obtained from the bridge-cleavage reaction of dinuclear Pd(II)-NSHC with triphenylphosphine, tricyclohexylphosphine and 2-diphenylphosphanyl-pyridine. Use of neutral aromatic N-bidentate heterocycles (aromatic N-bidentate heterocycles = pyrazine, 1,2-bis(4-pyridyl)ethane, 4,4¿-bipyridine and trans-1,2-bis(4-pyridyl)-ethylene) gave the dinuclear N-heterocycles bridged [Pd2Br4(NSHC)2(u-N-heterocycles)] complexes. A series of mononuclear trans-PdI2(NSHC)(pyridyl) [pyridyl = pyridine, 2-aminopyridine, 3-iodopyridine and 4-tert-butyl-pyridine] and trans-PdX2(NSHC)(azole) [X = Br, I, azole = imidazole, 1-(2, 4, 6-trimethyl-phenyl)-1H-imidazole, benzimidazole, benzothiazole and benzooxazole] have been synthesized andcharacterized. The catalytic activity of selected mixed-NSHC-ligand complexes has been studied. The coordination chemistry, spectroscopic properties and catalytic activities between N,S- and N,N-NHC Pd(II) are compared too. The ring-opening of benzothiazolium salts in the presence of a silver salt in devoted. Four cyclometallated Pt(II)-NSHC/NNHC complexes are compared. Finally, the formation of the 5-membered and 6-membered fused ring imidazolium salts from oxidative addition and reductive elimination involving an intermediate metal-hydride carbene complex observed by 1H NMR spectroscopy is presented.
URI: http://scholarbank.nus.edu.sg/handle/10635/17061
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1. YSK-Cover pages and dedication- 12 April 2010.pdf11.71 kBAdobe PDF

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2. YSK-Table of Content-12 April 2010(2).pdf43.01 kBAdobe PDF

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3. YSK-Acknowlegdements-12 April 2010.pdf15.48 kBAdobe PDF

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4. YSK-Abstract-12 April 2010.pdf18.15 kBAdobe PDF

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5. YSK-List of Table - 12 April 2010(2).pdf25.74 kBAdobe PDF

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6. YSK-List of Figures - 12 April 2010(2).pdf60.61 kBAdobe PDF

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7. YSK-List of Schemes - 12 April 2010(2).pdf32.95 kBAdobe PDF

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8. YSK-List Of Abbreviations-12 April 2010(3).pdf37.48 kBAdobe PDF

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9. YSK-List of Structure- 12 April 2010(2).pdf86.19 kBAdobe PDF

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10.YSK-Chapter 1_Introduction-12 April 2010.pdf211.02 kBAdobe PDF

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11.YSK-Chapter 2_Results and Discussion (All)-25 April 2010(2).pdf6.86 MBAdobe PDF

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13.YSK-Chapter_Four_Conclusion-12 April 2010(2).pdf48.18 kBAdobe PDF

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14.YSK-Reference-25 April 2010(2).pdf137.68 kBAdobe PDF

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15.YSK-Publication-12 April 2010(2).pdf34.23 kBAdobe PDF

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