Thesis (Ph.D.)--University of Adelaide, School of Chemistry and Physics, 2003. / Includes Publications resultant of the thesis research. Includes bibliographical references (leaves 180-196). Also available in print form.

Thesis--Wisconsin. / Vita. Includes bibliographical references.

The homogeneous hydrogenation of arenes with functional groups was studied with allylcobalt complexes containing the bulky chelating diphosphines dippp (1,3-bis(diisopropylphosphino)propane and dippcyp (trans-(±)-l,2-bis(diisopropylphos-phino)cyclopentane). The results indicated that these catalyst precursors were unsuitable for the hydrogenation reactions, being too sensitive to the nature of the substrate. From these hydrogenation reactions, the intermediates (η⁵-cyclohexadienyl)Co(dippcyp) (10) and (η⁴-2-methoxynaphthalene)Co(H)(dippcyp) (11) were isolated and structurally characterized, thus providing some insight into the mechanism of the hydrogenation reaction. The production of binuclear hydrides such as [(dippp)CoH₂]₂ (4) and [(dippcyp)CoH₂]₂ (9) was observed to lead to the end of the catalysis. An X-ray structural characterization of the blue hydride [(dippp)CoH₂]₂ (4) showed that in the solid state it is binuclear. Although the complex is diamagnetic in the solid state (6-280 K), in solution its paramagnetic behaviour could only be attributed to an equilibrium with a second species proposed to be mononuclear, (dippp)CoH₂. In addition, a cyclic voltammogram of the complex in solution indicated that the predominant species still was the binuclear compound [(dippp)CoH₂]₂ (4). One of the syntheses of [(dippp)CoH₂]₂ (4) gave a product identified as (dippp)CoH₃ (5). Based on variable-temperature spin-lattice relaxation time (T₁) measurements and an electrochemical study, this red hydride complex appeared to contain an η²-H₂ ligand. The relationship of this complex with the blue hydride apparently involves the mononuclear species, (dippp)CoH₂. Independent pathways led to the formation of both the blue and red hydrides, and these pathways are discussed in terms of possible mechanisms. / Science, Faculty of / Chemistry, Department of / Graduate

No description available.

A number of ligands that belong to the salen-type family were synthesized in this thesis. These ligands were synthesized from salicylaldehyde and 1,2-phenylenediamine, 1,3- diamino-2-hydroxypropane, 1,2-diamino-ethane, N-(3-aminopropyl)-1,3-propanediamine, diethylenetriamine, diaminomaleonitrile, 2,2-dimethyl-1,3-propanediamine and 1,3- diaminopropane. From this range of ligands, H2salophen was chosen as the ligand for further studies. This work is aimed primarily at elucidating the structures and spectroscopic properties of [Co(salophen)(amine)2](OAc) derivatives, where salophen is N,N’-disalicylidene-1,2- phenylenediamine and the amines used were butylamine, benzylamine, a- methylbenzylamine, dibutylamine, N-methylpiperazine and piperidine. Three novel crystal structures of [CoIII(salophen)L2]Cl derivatives, where L = butylamine, benzylamine, and piperidine, with Co-N distances that range from 1.901 Å to 2.024 Å, have been reported in this thesis. The novel crystal structure of [Co(salophen)(N-MePipz)(OAc)] is also reported in this thesis. These cobalt complexes have been analysed by 1H, 13C and 59Co NMR as well as electronic and IR spectroscopy. A 59Co NMR spectrum was obtained for the [Co(salophen)(BuNH2)2]CH2Cl2×Cl complex. The spectrum exhibits a single line at 8504 ppm. The binding constants of all [Co(salophen)(amine)2](OAc) complexes, where amine = butylamine, benzylamine, a-methylbenzylamine, dibutylamine, N-methylpiperazine and piperidine, were determined by spectroscopic titrations. The titrations were carried out at various concentrations of the amine and at temperatures ranging from 25°C to 45°C. It was found that the primary amines had much larger values of K1 and K2 compared to the secondary amines. Typical values of K1 and K2 were 8000 M-1 and 63.6 M-1 respectively at 25°C, for a-methylbenzylamine. Of the primary amines, it was found that a- methylbenzylamine had the largest value of K1 and K2 compared to the other two amines. For the secondary amines, it was found that N-methylpiperazine had the bigger value of K1 compared to that of dibutylamine. / Thesis (M.Sc. )-University of KwaZulu-Natal, Pietermaritzburg, 2007.

本論文主要研究了鹼性添加劑促進二價鈷卟啉絡合物(Co{U+1D35}{U+1D35}(por))在苯溶劑中與溴代苯及其衍生物(ArX)的反應及鹼性條件下，該絡合物催化溴代苯及其衍生物的脫鹵反應。 / 第一部分主要介紹了在KOH和{U+1D57}BuOH存在下，Co{U+1D35}{U+1D35}(por)斷裂碳-溴鍵（Ar-Br）形成各種三價鈷卟啉芳基絡合物（Co{U+1D35}{U+1D35}{U+1D35}(por)Ar）(eq. 1)。 / 機理研究顯示，Co{U+1D35}{U+1D35}(por)首先從ArBr中得到Br·形成芳基自由基（Ar·）及Co{U+1D35}{U+1D35}{U+1D35}(por)Br (Scheme 1, i). Ar 與另一個Co{U+1D35}{U+1D35}(por)反應得到Co{U+1D35}{U+1D35}{U+1D35}(por)Ar (Scheme 1, ii)。在鹼性條件中，Co{U+1D35}{U+1D35}{U+1D35}(por)Br 最終形成CoII(por)從而繼續反應 (Scheme 1, iii-iv)。 / 第二部份主要介紹了在200 ºC時， 鹼性條件下Co{U+1D35}{U+1D35}(por)催化鹵代苯及其衍生物脫鹵形成對應芳烴的反應 (eq. 2)。 該反應在四氫呋喃（THF）及異丙醇 ({U+2071}PrOH) 中都可以進行。 / 機理研究顯示， Co{U+1D35}{U+1D35}(ttp) 首先與ArBr反應得到Ar· 和Co{U+1D35}{U+1D35}{U+1D35}(ttp)Br (Scheme 2, i)。 Ar 從溶劑（THF 或者 {U+2071}PrOH）得到一個氫原子從而形成芳烴 (ArH) (Scheme 2, ii)。 Ar 也可以與另一個Co{U+1D35}{U+1D35}(ttp) 反應得到Co{U+1D35}{U+1D35}{U+1D35}(ttp)Ar。 在鹼性條件下， Co{U+1D35}{U+1D35}{U+1D35}(ttp)Ar水解形成ArH 和 Co{U+1D35}{U+1D35}{U+1D35}(ttp)OH (Scheme 2, iii)。 Co{U+1D35}{U+1D35}{U+1D35}(ttp)Br 與KOH進行取代反應得到Co{U+1D35}{U+1D35}{U+1D35}(ttp)OH, 并最終形成催化劑Co{U+1D35}{U+1D35}(ttp) (Scheme 1, iii-iv)。所以， 溶劑 （THF 或者 {U+2071}PrOH）及H₂O 都可以作為Co{U+1D35}{U+1D35}(ttp) 催化鹵代苯脫鹵形成芳烴的氫的來源。 / This thesis focuses on (1) the base-promoted aryl bromine bond (Ar-Br) cleavages by cobalt(II) porphyrins and (2) catalytic hydrodehalogenation of aryl bromides by cobalt(II) porphyrin in alkaline conditions. / Part I describes the aryl bromine bond cleavage with cobalt(II) porphyrin (Co{U+1D35}{U+1D35}(por)) in the presence of KOH and {U+1D57}BuOH in benzene at 150ºC to give cobalt(III) porphyrin aryls (Co{U+1D35}{U+1D35}{U+1D35}(por)Ar) (eq. 1). / [With images] / Mechanistic studies suggest that CoII(por) first abstracts the bromine atom from the aryl bromide to form aryl radical (Ar) and Co{U+1D35}{U+1D35}{U+1D35}(por)Br (Scheme 1, i). Ar· further reacts with Co{U+1D35}{U+1D35}(por) to generate Co{U+1D35}{U+1D35}{U+1D35}(por)Ar (Scheme 1, ii). Co{U+1D35}{U+1D35}{U+1D35}(por)Br undergoes ligand substitution with KOH to form Co{U+1D35}{U+1D35}{U+1D35}(por)OH, which quickly gives Co{U+1D35}{U+1D35}(por) and H₂O₂ (Scheme 1, iii). H₂O₂ undergoes base-promoted decomposition to form H₂O and O₂ (Scheme 1, iv). / [With images] / Scheme 1 Reaction Mechanism of Base-promoted Ar-Br Cleavage with Co{U+1D35}{U+1D35}(por) / Part II describes the catalytic hydrodehalogenation of aryl bromides by Co{U+1D35}{U+1D35}(ttp) at 200 ºC in alkaline conditions to generate arenes (eq. 2). The reaction can occur in both THF and {U+2071}PrOH. / [With images] / Mechanistic studies suggest that Co{U+1D35}{U+1D35}(ttp) also first abstracts the bromine atom from the aryl bromide in the presence of KOH to form Ar· and Co{U+1D35}{U+1D35}{U+1D35}(ttp)Br (Scheme 2, i). Ar· can abstract a hydrogen atom from the solvent (THF or {U+2071}PrOH) to form arenes (Scheme 2, ii). Ar also could be trapped by Co{U+1D35}{U+1D35}(ttp) to give Co{U+1D35}{U+1D35}{U+1D35}(ttp)Ar, which undergoes hydrolysis in the presence of OH⁻ to the arene (ArH) and Co{U+1D35}{U+1D35}{U+1D35}(ttp)OH (Scheme 2, iii). Co{U+1D35}{U+1D35}{U+1D35}(ttp)Br gives Co{U+1D35}{U+1D35}{U+1D35}(ttp)OH by ligand substitution with KOH and Co{U+1D35}{U+1D35}{U+1D35}(ttp)OH regenerates the catalyst Co{U+1D35}{U+1D35}(ttp) (Scheme 1, iii-iv). The solvent (THF or {U+2071}PrOH) and H₂O are the hydrogen sources for the catalytic dehalogenation of aryl bromides by Co{U+1D35}{U+1D35}(ttp). / Scheme 2 Mechanism of Catalytic Dehalogentaion of ArBr by CoII(ttp) in Alkaline Media / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Liu, Chunran. / "October 2012." / Thesis (M.Phil.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves ). / Abstracts also in Chinese. / Chapter Table of Contents --- p.i / Chapter Acknowledgements --- p.iv / Chapter Abbreviations --- p.v / Chapter Abstract --- p.vi / Chapter Part I --- The Base-promoted Aryl Bromine Bond Cleavage of Aryl Bromides by Cobalt(II) Porphyrins / Chapter Chapter 1 --- General Introduction --- p.1 / Chapter 1.1 --- Introduction to Porphyrins and Group 9 metalloporphyrins --- p.1 / Chapter 1.1.1 --- Porphyrin Ligand --- p.1 / Chapter 1.1.2 --- Group 9 metalloporphyrins --- p.2 / Chapter 1.1.3 --- Chemistry of Group 9 Metalloporphyrin --- p.3 / Chapter 1.1.3.1 --- Chemsitry of M{U+1D35}(por) --- p.3 / Chapter 1.1.3.2 --- Chemsitry of M{U+1D35}{U+1D35}(por) --- p.4 / Chapter 1.1.3.3 --- Chemsitry of M{U+1D35}{U+1D35}{U+1D35}{U+1D35}(por) --- p.4 / Chapter 1.1.3.4 --- Chemsitry of M{U+1D35}{U+1D35}{U+1D35}{U+1D35}(por)OH --- p.6 / Chapter 1.2 --- Physical Properties of Aryl Halides --- p.9 / Chapter 1.3 --- Synthesis of Metalloporphyrin Aryl --- p.10 / Chapter 1.4 --- Modes of Reactivity of Aryl Carbon-Halogen Bond Cleavage by Transition Metal Complexes --- p.11 / Chapter 1.4.1 --- Oxidative Addition (OA) --- p.11 / Chapter 1.4.2 --- Nucleophilic Aromatic Substitution (SNA) --- p.14 / Chapter 1.4.3 --- Halogen Atom Transfer (HXA) --- p.14 / Chapter 1.4.4 --- Radical ipso-Substitution --- p.15 / Chapter 1.5 --- Scope of Part I --- p.16 / Chapter Chapter 2 --- Base-promoted Aryl Bromine Bond Cleavage of Aryl Bromides by Cobalt(II) Porphyrins / Chapter 2.1 --- Introduction --- p.17 / Chapter 2.2 --- Objectives of the Work --- p.18 / Chapter 2.3 --- Preparation of Starting Materials --- p.18 / Chapter 2.3.1 --- Synthesis of Porphyrin --- p.18 / Chapter 2.3.2 --- Synthesis of Cobalt(II) Porphyrin --- p.18 / Chapter 2.3.3 --- Synthesis of Co{U+1D35}{U+1D35}{U+1D35}(ttp)Br --- p.19 / Chapter 2.4 --- Discovery of Ph-Br Bond Cleavage by Co{U+1D35}{U+1D35}(ttp) with KOH --- p.19 / Chapter 2.5 --- Optimization of Reaction Conditions --- p.20 / Chapter 2.5.1 --- {U+1D57}BuOH Effect --- p.20 / Chapter 2.5.2 --- Solvent Effect --- p.21 / Chapter 2.5.3 --- Temperature Effect --- p.21 / Chapter 2.5.4 --- Base Loading Effect --- p.22 / Chapter 2.6 --- Summary of Optimization of the Base-promoted Ph-Br Bond Cleavage by Co{U+1D35}{U+1D35}(ttp) --- p.22 / Chapter 2.7 --- Porphyrin Ligand Effect --- p.23 / Chapter 2.8 --- Substrate Scope of Aryl Bromides --- p.24 / Chapter 2.9 --- Mechanistic Studies --- p.25 / Chapter 2.9.1 --- Possible Pathways of Ar-Br Bond Cleavage --- p.25 / Chapter 2.9.1.1 --- Oxidative Addition (OA) --- p.26 / Chapter 2.9.1.2 --- Nucleophilic Aromatic Substitution (SNA) --- p.27 / Chapter 2.9.1.3 --- Radical ipso-Substitution --- p.28 / Chapter 2.9.1.4 --- Halogen Atom Transfer (HXA) --- p.28 / Chapter 2.9.2 --- Electronic Effect of 4-Substituted ArBr by Hammett Plot --- p.29 / Chapter 2.9.3 --- Proposed Mechanism --- p.32 / Chapter 2.9.4 --- Evidence for Halogen Atom Transfer --- p.33 / Chapter 2.10 --- Conclusion --- p.35 / Chapter Chapter 3 --- Experimental Section --- p.36 / Reference --- p.53 / Chapter Part II --- Catalytic Hydrodehalogenation of Aryl Bromides by Cobalt(II) Porphyrin in Alkaline Conditions / Chapter Chapter 4 --- General Introduction --- p.58 / Chapter 4.1 --- Introduction --- p.58 / Chapter 4.1.1 --- Properties of Halogenated Aromatic Compounds --- p.58 / Chapter 4.1.2 --- Reactivity of Aryl Carbon-Halogen Bond --- p.59 / Chapter 4.2 --- Hydrodehalogenation of Aryl Halides by Transiton Metal Complexes --- p.59 / Chapter 4.2.1 --- Molecular Hydrogen (H₂) --- p.60 / Chapter 4.2.2 --- Alcohols and Metal Alkoxides --- p.61 / Chapter 4.2.3 --- Dimethyformamide (DMF) --- p.64 / Chapter 4.2.4 --- Hydrazine (NH₂-NH₂) --- p.65 / Chapter 4.2.5 --- Metal Hydrides --- p.65 / Chapter 4.2.6 --- Alkyl Grignard Reagents --- p.67 / Chapter 4.2.7 --- Formic Acid and Its Salts --- p.67 / Chapter 4.3 --- Common Reducing Agents --- p.69 / Chapter 4.3 --- Scope of Part II --- p.69 / Chapter Chapter 5 --- Catalytic Hydrodehalogenation of Aryl Bromides by Cobalt(II) Porphyrin in Alkaline Conditions / Chapter 5.1 --- Introduction --- p.70 / Chapter 5.2 --- Objectives of the Work --- p.71 / Chapter 5.3 --- Optimization of Reaction Conditions --- p.71 / Chapter 5.3.1 --- Solvent Effect --- p.71 / Chapter 5.3.2 --- Temperature Effect --- p.72 / Chapter 5.3.3 --- Base Loading Effect --- p.73 / Chapter 5.3.4 --- Porphyrin Loading Effect --- p.73 / Chapter 5.3.5 --- Atmosphere Effect --- p.74 / Chapter 5.4 --- Summary of Optimization of Hydrodehalogention of Aryl Bromides by Co{U+1D35}{U+1D35}(ttp) --- p.74 / Chapter 5.5 --- Substrate Scope of Aryl Bromides --- p.75 / Chapter 5.5.1 --- THF as the Solvent --- p.75 / Chapter 5.5.2 --- {U+2071}PrOH as the Solvent --- p.76 / Chapter 5.6 --- Catalytic Reactivity of Co{U+1D35}{U+1D35}(ttp) as the Catalyst --- p.77 / Chapter 5.7 --- Mechanistic Studies --- p.78 / Chapter 5.7.1 --- Proposed Mechanism of Hydrodehalogenation of Aryl Bromides by Co{U+1D35}{U+1D35}(ttp) --- p.78 / Chapter 5.7.2 --- Hydrogen Source Investigation --- p.80 / Chapter 5.8 --- Conclusion --- p.83 / Chapter Chapter 6 --- Experimental Section --- p.84 / Reference --- p.92 / Chapter Appendix --- Appendix I --- p.101 / Appendix II --- p.112 / Appendix III --- p.118

Thesis (Ph. D)--Montana State University--Bozeman, 2005. / Typescript. Chairperson, Graduate Committee: Tom Livinghouse. Includes bibliographical references (leaves 138-144).

Thesis (Ph.D.)--University of Delaware, 2006. / Principal faculty advisor: Charles G. Riordan, Dept. of Chemistry and Biochemistry. Includes bibliographical references.

The novel complexes [special characters omitted] and [special characters omitted] were prepared and characterized. Photoredox quantum yields for the formation of [special characters omitted] from the above compounds were measured on irradiation at 360 nm to be 0.065, 0.082, 0.0088 and 0.0040 respectively. With added thiocyanate a significant increase in ΦCo2+ occurred. This can be modeled in two ways; (i) scavenging of thiocyanate radical from an initial caged radical pair giving 6-25 ps estimates for the lifetime of the latter species; (ii) photolysis of a thiocyanate/complex ion pair, giving formation constants of 0.19, 0.09, 0.08 and 0.05 for the complexes [special characters omitted] and [special characters omitted] respectively. Subnanosecond laser flash photolysis studies showed evidence for the formation of [special characters omitted]. The effects of added electrolytes and of viscosity on the formation and decay of [special characters omitted] were also investigated. To help to distinguish between the above two mechanisms, the zero-charged novel complex [special characters omitted] (tacn = 1,4,7-triazacyclononane) was synthesized and characterized. It is thermally stable in aqueous/DMSO solution, but on irradiation at 360 nm undergoes parallel photosubstitution to form DMSO and aqua-substituted products with an overall quantum yield of 0.012. The product yields increase linearly with added thiocyanate. For a 1 M thiocyanate solution, the quantum yield for disappearance of the starting complex rose to 0.022 and a small redox yield of 0.0008 was found. Under these same conditions, ns laser flash photolysis at 355 nm revealed a transient absorption owing to [special characters omitted], which was produced with a quantum yield of 0.036. These results are interpreted in terms of scavenging of radical pair species by thiocyanate ion followed by back electron transfer to give a photosubstituted product, and a radical pair quantum yield of 0.29 and lifetime of 12 ps was derived. The emission of [special characters omitted] (where pop = μ-pyrophosphite-P,P’) can be quenched by the complexes [special characters omitted] (where X = [special characters omitted]) only in the presence of electrolytes. The salt effects have been studied using the salts MCl, M'Cl2, or [special characters omitted] (where M, M’ and R represent alkali, alkaline earth metals, and alkyl respectively, with n = 0-3), and [special characters omitted]. For 0.5 M cation concentration, second-order quenching rate constants kq lie in the range [special characters omitted]. For the different quencher complexes used, kq decreases in the order [special characters omitted]. The oxidative quenching products [special characters omitted] are observed, and their quantum yields are 0.083 and 0.027 respectively for the reaction of [special characters omitted] with [special characters omitted] and [special characters omitted] in 0.5 M KCl / pH2 solution. The quenching occurred by atom transfer (dominant) and electron transfer (minor) for quencher [special characters omitted] or [special characters omitted], while only electron transfer was observed for [special characters omitted] and [special characters omitted] quenchers. The quenching efficiency of the cobalt complexes increases with electrolyte concentration and specific cation effects are observed in the kq with the following trends Li+ < Na+ < K+ < Cs+: Mg2+ < Ca2+ < Sr2+ < Ba2+; NH4+ < MeNH3+ < Me2NH2+ < Me3NH+: Et3NH+ < Et2NH2+ < EtNH3+: n-PrNH3+ < EtNH3+ < MeNH3+. / Graduate

No description available.