*Please refer to dissertation for diagrams. / Part I describes the silicon-hydrogen bond activation (SiHA) of silanes with both electron-deficient iridium porphyrin carbonyl chloride (Ir(ttp)Cl(CO)) and electron-rich iridium porphyrin methyl (Ir(ttp)Me) to give iridium(III) porphyrin silyls (Ir(ttp)SiR3). Firstly, Ir(ttp)SiR3 were synthesized in moderate to good yields conveniently from the reactions of Ir(ttp)Cl(CO) and Ir(ttp)Me with silanes, via SiHA in solvent-free conditions and non-polar solvents at 200°C. Base facilitated the SiHA reaction even at lower temperature of 140°C. Specifically, K3PO4 accelerated the SiHA with Ir(ttp)Cl(CO), while KOAc promoted the SiHA by Ir(ttp)Me. Mechanistic experiments suggest that Ir(ttp)Cl(CO) initially forms iridium porphyin cation (Ir(ttp)+), which then reacts with silanes likely via heterolysis to give iridium porphyrin hydride (Ir(ttp)H). Ir(ttp)H further reacts with silanes to yield Ir(ttp)SiR3. On the other hand, Ir(ttp)Me and Ir(ttp)SiR3 undergo either oxidative addition (OA) or sigma-bond metathesis (SBM) to form the products. In the presence of base, a penta-coordinated silicon hydride species likely forms and reacts with Ir(ttp)Me to form iridium porphyrin anion (Ir(ttp) -) that can further react with silane to yield Ir(ttp)H after protonation. Ir(ttp)H finally reacts with excess silane to give Ir(ttp)SiR 3.* / Part II describes successful base promoted aromatic carbon-fluorine (C-F) and carbon-hydrogen (C-H) bond activation of fluorobenzenes in neat conditions to give the corresponding iridium(III) porphyrin aryls (Ir(ttp)Ar) at 200°C in up to 95% yield. Mechanistic studies suggested that Ir(ttp)SiEt3 is firstly converted to Ir(ttp)- in the presence of KOH. Ir(ttp)- cleaves the aromatic C-F bond via an S NAr process. As the reaction proceeds, a hydroxide anion can coordinate to the iridium center of Ir(ttp)Ar to form an iridium porphyrin trans aryl hydroxyl anion (trans-[ArIr(ttp)OH]-). In the presence of water, trans-[ArIr(ttp)OH]- can give Ir(ttp)OH and ArH. Ir(ttp)OH then undergoes aromatic C-H bond activation reaction to give Ir(ttp)Ar'. Furthermore, the aromatic C-F bond activation products were found as the kinetic products, and aromatic C-H bond activation products were the thermodynamic ones.* / Part III describes the successful C(C=O)-C(alpha) bond activation of acetophenones by high-valent iridium porphyrin complexes (Ir(ttp)X, X = Cl(CO), (BF4)(CO), Me) in solvent-free conditions at 200°C to give the corresponding iridium porphyrin benzoyls (Ir(ttp)COAr) in up to 92% yield. Mechanistic studies suggest that Ir(ttp)X reacts with acetophenones to give alpha-CHA product as the primary product, which can re-convert back to the active intermediate Ir(ttp)OH or Ir(ttp)H in the presence of water formed from the concurrent iridium-catalyzed aldol condensation of acetophenones. Then Ir(ttp)OH cleaves the aromatic C-H bonds to produce the aromatic CHA products, which are more thermally stable than the alpha-CHA product. Both Ir(ttp)H and Ir(ttp)OH were the possible intermediates to cleave the C(C=O)-C(alpha) bond to give thermodynamic products of Ir(ttp)COAr. On the other hand, only Ir(ttp)(BF 4)(CO) can react with the aliphatic ketones, likely due to the stronger Lewis acidity and the HBF4 generated in catalyzing the aldol condensation of aliphatic ketones to facilitate the formation of Ir(ttp)OH and Ir(ttp)H.* / The objectives of the research focus on the bond activation chemistry by iridium porphyrin complexes with three organic substrates, (1) hydrosilanes (HSiR3), (2) fluorobenzenes (C6HnF6-n , n = 0--6), and (3) aromatic or aliphatic ketones (RCOR, R = alkyl or aryl). / Li, Baozhu. / Adviser: Kin Shing Chan. / Source: Dissertation Abstracts International, Volume: 72-01, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese.
| Identifer | oai:union.ndltd.org:cuhk.edu.hk/oai:cuhk-dr:cuhk_344469 |
| Date | January 2010 |
| Contributors | Li, Baozhu., Chinese University of Hong Kong Graduate School. Division of Chemistry. |
| Source Sets | The Chinese University of Hong Kong |
| Language | English, Chinese |
| Detected Language | English |
| Type | Text, theses |
| Format | electronic resource, microform, microfiche, 1 online resource (xii, 228 leaves : ill.) |
| Rights | Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/) |
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