Thesis (Ph. D.)--University of Oregon, 2004. / On t.p. "m̲" and "n̲" are subscript. Typescript. Includes vita and abstract. Includes bibliographical references (leaves 147-153). Also available for download via the World Wide Web; free to University of Oregon users.

Thesis (M.S.)--Florida State University, 2004. / Advisor: Dr. Albert E. Stiegman, Florida State University, College of Arts and Sciences, Dept. of Chemistry and Biochemistry. Title and description from dissertation home page (viewed June 17, 2004). Includes bibliographical references.

Thesis (Ph. D.)--University of Hong Kong, 1990.

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M.Sc. / This study comprises the preparation and characterisation of new azolinylidene- and divinylcarbene complexes of chromium, molybdenum and tungsten, from 1- phenylpyrawle, 1-methylimidazole and 4,4-dimethyl-2,2-thienyloxazoline precursors. The reaction of 1-phenylpyrazolyllithium with (C0) 6M (M Cr, Mo or W) yields after alkylation with CH3S03CF3 in THE the two products (C0)5M[C(OCH3X(ONPhNCHC(H)] and (C0)5M[C(0{CH2}40C113)(aNPhNCH6H)]. A 'H NMR study indicates the existence of two isomers for each of the two tungsten CO'cli•lexes. 1-Methylimidazolyllithiura reacts with (CO)6M (M = Cr, Mo or W) to give the carbene complexes (C0)5MK'N(CH3)CHCH14(C I i 3)] after alkylation with CH3S03CF3, and the imine complexes (C0)5MOCHN(CH3)CH6H] after protonation with SO3CF3. Reaction of 1-methylimidazolyllithium with the anionic salt (C0)5 Cl = Cr or W), followed by alkylation with CH3S03CF3 affords both the mono- and bis(carbene) complexes, (CO)5M[CN(CH3)CHCHN(CH3)] and (C0)41v1[6N(CH3)CHCIRA(CH3)]2. The complex (C0)5W[C(0 {CH2 } 40C113)(t‘NPhNaldH)] reacts with phenylethynthiolate to furnish an anionic organometallic synthon that can either be alkylated or protonated. Protonation leads to two isomeric forms of the metal-coordinated thioaldehyde, (C0)5W4—SHC(Ph)=C(OCH3)(oNPhNCHell), whilst alkylation with various electrophilic reagents produces the metal coordinated dithio-esther (C0)5 W4--S=C [ SCH3] [C(Ph)=C(OCH3)(tNPhNaldH)]. The neutral divinylcarbene complexes (C0)5Cr{cC(a0CH2CMe2N)SC CH} (a) and (C0)5W{cC(COCH2CMe214)SCH9H} (19) are prepared by reaction of (C0)5MCr with the 3-lithiated thienyloxazoline, followed by alkylation with CH3S03CF3 . These complexes are the first examples of coordinated 'divinylcarbenes utilizing the group 6 transition metals, where the carbene carbon shows carbene character. They are also in another sense unique since the nucleopbutlic heteroatom where alkylation occurs, is situated outside the coordinated ring-system, and, therefore, more than two bonds removed fro the carbene carbon atom.

Thesis (MSc)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: Please refer to fulltext for abstract / AFRIKAANSE OPSOMMING: Sien asb opsomming vir volteks

M.Sc. / In search of developing new pyrazolyl complexes that can be used for ethylene transformation reactions, bis(pyrazolyl)alky carbonyl and amine complexes were prepared. The reaction between 3,5-dimethylpyrazole with alkyl-carbonyl chloride linkers in the presence of triethylamine as a base produced the ligands, 1,3-bis(3,5- dimethylpyrazol-1-yl)-propan-1-one (L1), 1,2-bis(3,5-dimethylpyrazol-1-yl)-ethane- 1,2-dione (L2), 1,4-bis(3,5-dimethylpyrazol-1-yl)-butane-1,4-dione (L3) and 1,6- bis(3,5-dimethylpyrazol-1-yl)-hexane-1,6-dione (L4) as white to brown crystalline solids in good yields. Ligand L5 was prepared by using bis(2-chloroethyl)-amine hydrochloride and 3,5- dimethylpyrazolevia via a phase-transfer reaction, while L6 was obtained using the bis(2-chloroethyl)-amine hydrochloride and 3,5-diphenypyrazole in the presence of triethylamine as a base. They were isolated in moderate yields, while their ditertiarypyrazole derivative was not obtained at all. All the ligands were characterized by a combination of 1H and 13C{1H}-NMR spectroscopy, infrared spectroscopy, elemental analysis and mass spectrometry. Ligands L1 and L4 were further confirmed by X-ray crystallography. Ligands L1 and L6 were subsequently used to prepare their corresponding Pd, Ni and Cr complexes. L1 was reacted with [PdCl2(NCMe)2] to form a bidentate complex 1,3- bis-(3,5-dimethylpyrazol-1-yl)-propan-1-one palladium dichloride (1a) when the reaction was heated at 80 oC, while a tridentate complex 1,3-bis(3,5-dimethylpyrazol- 1-yl)-propan-1-one palladium chloride (1b) was obtained when the reaction was refluxed. 1,3-bis(3,5-dimethylpyrazol-1-yl)-propan-1-one nickel(II) bromide (2) was obtained when NiBr2 was reacted with L1 at room temperature while the reaction between L1 and [CrCl3(THF)3] gave 1,3-bis(3,5-dimethylpyrazol-1-yl)-propan-1-one chromium(III) chloride (3). Ligand L6 was reacted with the same metal salts to give bis[2-(3,5-dimethylpyrazol- 1-yl)-ethyl] amine palladium(II) chloride (4), bis[2-(3,5-dimethylpyrazol-1-yl)-ethyl] amine nickel(II) chloride (5) and bis[2-(3,5-dimethylpyrazol-1-yl)-ethyl] amine chromium(III) chloride (6). All the complexes were characterized by the already mentioned characterization techniques and X-ray analysis was performed for 1b and 4. Ethylene transformation reactions were performed with complexes 1a, 2, 3, 5 and 6, and complexes 1a and 4 were not used because of their geometrical structures, which prevented them to be active for such reactions. Using MMAO and EtAlCl2 as cocatalysts complexes 1a and 3 showed no activity, however complexes 2 and 6 were active. Complex 2 was used with MMAO and showed no activity, while with EtAlCl2 oligomers were produced. Gas-chromatography analysis of the products showed that C6-C14+ oligomers were obtained. Temperature variation reactions performed under standard conditions of 20 bar ethylene pressure and 200 equivalents of EtAlCl2 in one hour showed that certain oligomers were not favoured under certain temperatures. Ethylene reactions with complex 6 and EtAlCl2 did not form any product but with MMAO polymer material was obtained. Analysis of the polymer by differential scanning calometry proved that the product was high density polyethylene. Studies of temperature, co-catalyst and pressure variations were performed. As expected for temperature studies the catalyst decomposed at high temperatures (above 40 oC), while for co-catalyst studies 3000 equivalents of MMAO gave the lowest TON. Pressure variations studies showed that an increase in ethylene pressure also increased the TON, but above 30 bar the activity became stable.

Thesis--University of Oklahoma. / Bibliography: leaves 36-37.

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