published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

A new class of ruthenium-COD complexes containing carbon-bridged carboranyl-cyclopentadienyl (-indenyl or -fluorenyl) ligands was synthesized. These complexes showed a different reactivity in COD displacement reactions in comparison with the classical LRuCl(COD) (L = Cp, indenyl) complexes presumably due to the presence of sterically bulky and constrained organic-inorganic hybrid ligands. However, the COD ligands in these complexes can be replaced by bidentate tertiary phosphines, 2,2'-bipyridine, mono-phosphites with small cone angles, primary amines or N-heterocyclic carbene to give the corresponding COD displacement complexes. The ruthenium-amine complexes are much more labile than the ruthenium-COD ones. The amine ligands can be substituted by CH3CN to afford more active ruthenium-acetonitrile complex. / Reactions of dilithium salt of linked cyclopentadienyl-carboranyl ligands with 1 equiv of RuCl2(PPh3)3 in THF afforded the corresponding doubly-linked cyclopentadienyl-carboranyl ruthenium(II) hydride complexes. Such intramolecular coupling of a cyclopentadienyl with an o-carboranyl unit is driven by steric factors. Both carboranyl and phosphines with large cone angles are essential for such coupling reactions. The doubly-linked cyclopentadienyl-carboranyl compound was released from the corresponding ruthenium hydride complex by treatment with excess HBF 4·OEt2, followed by hydrolysis. This ligand is not accessible by any other known methods. / Reactions of the ruthenium-acetonitrile complex with SiMe3 substituted alkynes afforded mononuclear bis(vinylidene)metal or vinylvinylidenemetal, respectively, indicating that sterically demanding ancillary ligand and bulky alkynes are both important components to stabilize the above complexes. Treatment of the ruthenium-acetonitrile complex with internal alkynes afforded eta 4-Ru cyclobutadiene or ruthenacyclopentatriene complexes, respectively. Interestingly, interaction of ruthenium-acetonitrile complex with terminal aromatic alkynes gave ruthenium tricyclic complexes involving coupling reactions between Cp and alkynes. The possible reaction mechanism was proposed with the help of the DFT calculations. / Reactions of the ruthenium-amine complex with alkynes gave ruthenium aminocarbene or enamine complexes depending on the electronic properties of alkynes. Electron-rich alkynes gave aminocarbene complexes, whereas electron-deficient alkynes afforded enamine ones. The [eta5:sigma-Me 2C(C5H4)(C2B10H10)]Ru fragment remained intact during the reactions, which may play a role in these controlled reactions. / Sun Yi. / "May 2006." / Adviser: Zuowei Xie. / Source: Dissertation Abstracts International, Volume: 67-11, Section: B, page: 6398. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 157-177). / 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, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

M.Sc. / In this study, the pyrazolyl-based ligands were synthesised and used in the synthesise of new ruthenium pyrazolyl-based complexes. The ruthenium pyrazolyl-based complex 2.4 was tested as a catalyst for the self-metathesis reaction of 1-octene. The N^N ligands: 2-(3,5-dimethylpyrazol-1-ylmethyl)pyridine (L1) and 4-(3,5- dimethylpyrazol-1-ylmethyl)pyridine (L2) were prepared from the reaction of 2- picolyl chloride (for L1) and 4-(bromomethyl)pyridine (for L2) with 3,5- dimethylpyrazole. Reactions of L1 and L2 with [RuCl2(PPh3)3] and [RuCl3·3H2O] produced [2-(3,5-dimethyl-pyrazol-1-ylmethyl)pyridine) dichlorotriphenylphosphine]ruthenium (2.1) and bis[4-(3,5-dimethylpyrazol-1- ylmethyl)pyridine-trichloride]ruthenium (2.3), respectively. The N^O ligands: 2- (3,5-dimethylpyrazol-1-yl)ethanol (L3), 2-(3,5-diphenylpyrazol-1-yl)ethanol (L4), were prepared from the reaction of 2-hydroxyethylhydrazine (for L3) and dibenzoylmethane (for L4) with 2-hydroxyethylhydrazine. Reaction of L3 with (3-phenylindenylidene)dichlorobis-(triphenylphosphine)ruthenium produced [3-phenylindenylidene-(3,5-dimethylpyrazol-1-yl)-ethanolate chlorotriphenylphosphine]ruthenium (2.4). Ligands, 2-(3,5-dimethylpyrazol-1-ylmethyl)-phenol (L5) and bis(3,5- dimethylpyrazol-1-yl)acetic acid (L6), were prepared from the reaction of o-(α- bromo-methyl) phenyl methanesulfonate (for L5) and dibromoacetic acid (for L6) with 3,5-dimethylpyrazole. Reaction of L6 with [RuCl2(PPh3)3] produced bis-[(3,5-dimethylpyrazol-1-yl)-acetic-acid-chloro(bistriphenylphosphine)] ruthenium (2.6). The C^N ligands: 1-[2-(3,5,-dimethylpyrazol-1-yl)-ethyl]-3- methyl-3H-imidazol-1-ium bromide (L7) and 1-[2-(3,5,-dimethylpyrazol-1-yl)- ethyl]-3-methyl-3H-imidazol-1-ium bromide (L8) were prepared from the reaction of 1-(2-bromoethyl)-3,5-dimethyl-1H-pyrazole (for L7) and 1-(2- bromoethyl)-1H-pyrazole (for L8) with 1-methylimidazole. Reactions of L7 and L8 with silver(I) oxide (Ag2O) produced 3,5-dimethyl-1-[2-(3-methyl-2,3- dihydro-imidazol-1-yl)-ethyl-1H-pyrazole]silver bromide (2.7) and 1-[2-(3- methyl-2,3-dihydro-imidazol-1-yl)-ethyl-1H-pyrazole]silver bromide (2.8), respectively. Reactions of silver complexes (2.7) and (2.8), respectively, with [RuCl2(PPh3)3] produced 3,5-dimethyl-1-[2-(3-methyl-2,3-dihydro-imidazol-1- yl)-ethyl-1H-pyrazole-dichloro(triphenylphosphine)]ruthenium (2.9) and 1-[2- (3-methyl-2,3-dihydro-imidazol-1-yl)-ethyl-1H-pyrazoledichloro (triphenylphosphine)]ruthenium (2.10). The synthesised complexes were obtained in moderate to low yields and were characterised by 1H, 13C{1H}, 31P{1H} NMR, IR spectroscopy, mass spectrometry, elemental analyses and ligand L5 was also characterised by X-ray crystallography. Complex 2.4 was screened for self-metathesis reaction of 1-octene. Initial run from 30-90 oC showed no activity for 1-octene metathesis below 105 oC. At 105 oC small amounts of 7-tetradecene was obtained, indicating that metathesis reaction occurs at very high temperatures (105 oC). Thermal stability test of complex 2.4, showed that rearrangement in the proposed structure of complex 2.4 occurs after heating at 90 oC for 16 h, this was evident by the 31P{1H} NMR spectrum of complex 2.4 obtained as a singlet at 28.9 ppm (after being heated), (complex 2.4 appears at 30.0 ppm before heating). From the 31P{1H} NMR study, it could be proposed, that the pyrazole arm of the ligand dissociates thus influencing the environment of the phosphorus (of the triphenylphosphine), and therefore a shift in the peaks is observed.

M.Sc. (Chemistry) / Compounds 2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyl diphenlyphosphinite (L1), 2-(3,5-di-tert-butyl-1H-pyrazol-1-yl)ethyl diphenlyphosphinite (L2), 2-(3,5-diphenyl-1H-pyrazol-1-yl)ethyl diphenylphosphinite (L3), 2-(3,5-di-tert-butyl-1H-pyrazol-1-yl)ethyl diethylphosphite (L4), 2-(3,5-di-tert-butyl-1H-pyrazol-1-yl)ethyl diethylphosphite (L5) and 2-(3,5-diphenyl-1H-pyrazol-1-yl)ethyl diethylphosphite (L6) were synthesized and characterized by 1H NMR, 31P{1H} NMR and 13C{1H} NMR spectroscopy. Reactions of L1–L6 with [Ru(p-cymene)Cl2]2 in 2:1 ratio formed six neutral complexes, [Ru(p-cymene)Cl2(L1)] (1), [Ru(p-cymene)Cl2(L2)] (2), [Ru(p-cymene)Cl2(L3)] (3), [Ru(p-cymene)Cl2(L4)] (4), [Ru(p-cymene)Cl2(L5)] (5) and [Ru(p-cymene)Cl2(L6)] (6). The neutral complexes 1–6 were converted to salts of the general formula [Ru(p-cymene)ClL]X and [NaRu(p-cymene)Cl2L]X {X = BArF- or BPh4-} (1a,1b, 2a, 2b, 3a, 4a, 4b, 5a, 5b, and 6a) by reaction of complexes 1–6 with NaBArF (BArF = 3,5-CF3(C6H3) and/or NaBPh4 in 1:1 ratio. Neutral and ruthenium complexes and their salts were characterized by a combination of 1H, 31P{1H} and 13C{1H} NMR spectroscopy, mass spectrometry, elemental analysis and in selected cases by single crystal X-ray crystallography.

M.Sc. (Chemistry) / The main aim of this study was to use pyrazolyl-based bi-and tri-dentate ligands in the synthesis of several p-cymene-ruthenium complexes. These ruthenium complexes and their corresponding ligands were subsequently tested for their anticancer and antimalarial activities...

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy