• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 188
  • 20
  • 18
  • 4
  • 3
  • 2
  • 1
  • 1
  • Tagged with
  • 261
  • 261
  • 261
  • 84
  • 66
  • 48
  • 43
  • 25
  • 20
  • 19
  • 18
  • 15
  • 13
  • 13
  • 12
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Spectral intensities in planar copper(II) complexes

Essex, Sarah Jane January 1992 (has links)
No description available.
62

Comparative X-ray Structure Analyses of Multidentate Transition Metal Complexes

Flood, Kelly-Jayne January 2006 (has links)
The biological significance of macrocyclic complexes has been recognized since they were first synthesized by Neil Curtis. They have the potential to play a critical role in mimicking metalloprotein active sites. Nine Curtis macrocyclic complexes have been studied using X-ray crystallographic techniques. Their structures have been solved and comparisons of the results have been made. Biological importance is also true of the macrocyclic counterpart; side-off and end-off compartmental ligands. In some circumstances these types of ligands are more appropriate because they have extra flexibility due to their pendant arms not being fixed in place by another head-unit, like a traditional macrocycle. The synthesis of a proposed compartmental ligand; 2,2-(N,Nʼ-bis(benzimidazole-2-ylmethyl)methylamine-5,5ʼ-di-tert-butyl-3,3ʼmethanediyl-dibenzyl alcohol (Ligand 1(L1)), has been proposed and outlined. The pendant arms: bis(benzimidazole-2-ylmethyl)amine (BBIM), were successfully synthesized and characterized with 1H NMR, IR and X-ray crystallography. The head-unit: 5,5ʼ-Di-tert-butyl-2,2ʼ-dihydroxy-3,3ʼ-methanediyl-dibenzene methanol (DHTMBA), of L1 was synthesized and characterized using 1H NMR, IR and mass spectrometry. A similar head-unit; 5,5ʼ-Di-methyl-2,2ʼ-dihydroxy-3,3ʼ-methanediyl-dibenzene methanol (DHMMBA), was synthesized in an effort to shorten the synthetic time of the head-unit. This was consequently converted to the chlorine analogue; 3,3ʼ-Bis(chloromethyl)-5,5ʼ-dimethyl-2,2ʼ-methane-diyldiphenol (Cl-DHMMB), and characterized with 1H NMR, IR and X-ray crystallography. Efforts were made to synthesize Ligand 1, but due to synthetic difficulties and time restraints this proved unsuccessful. Suggestions have been made to develop this synthesis.
63

Asymmetric epoxidations using molecular oxygen

Rowling, Simon January 1996 (has links)
No description available.
64

Structural and bonding studies on polynuclear metal complexes: Part I, transition metal polychalcogenides from hydro(solvo)thermal synthesis : Part II, double salts of silver acetylide/pseudohalide with soluble silver salt. / Part I, transition metal polychalcogenides from hydro(solvo)thermal synthesis / Transition metal polychalcogenides from hydro(solvo)thermal synthesis / Part II, double salts of silver acetylide/pseudohalide with soluble silver salt / Double salts of silver acetylide/pseudohalide with slouble silver salt / CUHK electronic theses & dissertations collection

January 1999 (has links)
Guo-cong Guo. / "June 1999." / Thesis (Ph.D.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.
65

Main Group and Transition Metal Complexes Supported by Multidentate Tripodal Ligands that Feature Nitrogen, Oxygen and Sulfur Donors: Synthesis, Structural Characterization and Appliations

Rong, Yi January 2013 (has links)
Chapter 1 focuses on the computational study of Zr(CH2Ph)4 and chapter 2 discusses synthesis, characterization and density functional study of 2-imidazolethione. Chapters 3 - 6 describe the synthesis, structural characterization several multidentate tripodal ligands, namely tris(mercaptoimidazolyl)-hydroborato ligand, [TmR], tris(2-pyridylseleno)methyl ligand, [Tpsem], bis(2-pyridonyl)(pyridine-2-yloxy)methyl ligand, [O-poBpom] and allyl-tris(3-t-butylpyrazolyl)borato ligand, [allylTpBut], and their application to main group and transition metals. Chapter 1 describes the analysis of a monoclinic modification of Zr(CH2Ph)4 by single crystal X-ray diffraction, which reveals that the Zr-CH2-Ph bond angles in this compound span a range of 25.1°; that is much larger than previously observed for the orthorhombic form (12.1°;). In accord with this large range, density functional theory calculations demonstrate that little energy is required to perturb the Zr-CH2-Ph bond angles in this compound. Furthermore, density functional theory calculations on Me3ZrCH2Ph indicate that bending of the Zr-CH2-Ph moiety in the monobenzyl compound is also facile, thereby demonstrating that a benzyl ligand attached to zirconium is intrinsically flexible, such that its bending does not require a buffering effect involving another benzyl ligand. Chapter 2 describes the structure of 1-t-butyl-1,3-dihydro-2H-benzimidazole-2-thione which has been determined by X-ray diffraction. The compound exists in the chalcogenone form instead of chalcogenol form, which is similar to its oxo and selone counterparts. Comparison of 2-imidazolone, 2-imidazolethione and 2-imidazoleselone compounds shows that two N-C-E bond angles in the chalcogenone forms are not symmetric. This trend can be reproduced by density functional theory calculations. Additionally, H(mbenzimBut) has intermolecular hydrogen bonding interactions, whereas its selenium counterpart does not. The C-E bond lengths of 2-imidazolone, 2-imidazolethione and 2-imidazoleselone compounds are intermediate between those of formal C-E single and double bonds, which is in accord with the notion that zwitterionic structures that feature single C+-E- dative covalent bonds provide an important contribution in such molecules. Furthermore, NBO analysis of the bonding in H(ximBut) derivatives demonstrates that the doubly bonded C=E resonance structure is most significant for the oxygen derivative, whereas singly bonded C+-E- resonance structures dominate for the tellurium derivative. This result appears to be counterintuitive, based on the fact that it opposes the trend that one would expect on the basis of electronegativity difference, however, studies on XC(E)NH2 derivatives provide solid support for it. In this regard, the C~E bonding in these compounds is significantly different to that in chalcogenoformaldehyde derivatives for which the bonding is well represented by a H2C=E double bonded resonance structure. Chapter 3 describes the computational study on [TmMeBenz] anion and the synthesis and characterization of [TmButBenz]Na, [TmButBenz]Tl and [TmButBenz]Tl. It is worth noting that the two thallium compounds are the first structurally characterized monovalent monomeric [TmR]Tl complexes. Chapter 4 describes the synthesis and characterization of a few [TmR]M (M = Ti, Zr, Hf) complexes, including (i) Cp[TmBut]TiCl2 and Cp[TmBut]ZrCl2, which are analogues of Cp2TiCl2 and Cp2ZrCl2; (ii) [TmBut]Zr(CH2Ph)3 and (iii) [TmBut]Hf(CH2Ph)3 and [TmAd]Hf(CH2Ph)3, which are the first structurally characterized [TmR]Hf complexes. Chapter 5 describes two multidentate, L3X type ligands, which feature [CN3] and [CNO2] donors, namely tris(2 pyridylseleno)methane, [Tpsem]H, and bis(2-pyridonyl)(pyridin-2-yloxy)methane, [O-poBpom]H. They have been synthesized, characterized, and employed in the synthesis of zinc and cadmium complexes. Chapter 6 describes the synthesis and structural characterization of a new [Tp] ligand featuring an allyl substituent on the central boron atom, namely [allylTpBut]Li is reported. The compound reacts steadily with CH3CH2SH under 350 nm UV light via a thiol-ene click reaction. The resulting [CH3CH2S(CH2)3TpBut]Li complex can further react with metal halide. For example, the reaction of [CH3CH2S(CH2)3TpBut]Li with ZnI2 produced [CH3CH2S(CH2)3TpBut]ZnI at room temperature. This study provides a simple model on the immobilization of [Tp] metal complexes to the polymer chains with -SH terminals.
66

Synthesis, structural characterization and reactivity of late transition metal complexes containing P,N-donor phosphine ligands. / CUHK electronic theses & dissertations collection

January 2002 (has links)
Song Haibin. / "March, 2002." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (p. 137-151). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.
67

Synthesis, structure and oxygenation reactivity of copper complexes supported by monodentate arylamido ligands.

January 2013 (has links)
本研究主要集中在苯胺基配體及全氟苯胺基配體 [N(R')(2,6-R₂C₆H₃)]⁻ [R = Me, Pr{U+2071} ; R' = SiMe₃, SiBu{U+1D57}Me₂, C₆F₅] 衍生出來的一價銅的配位化學,包括其絡合物的合成、結構及氧化反應的研究。 / 第一章概括地介紹了金屬胺他物及銅配合物氧化反應的研究背景。 / 第二章敘述了由苯胺基配體所衍生的一價銅絡合物的裝備及結構。透過苯胺基鹼金屬絡合物 [(M)N(R')(2,6-R₂C₆H₃)] (M = Li, K) 與銅鹵化物CuX (X = Cl, I) 反應,成功合成一系列一價銅絡合物 [Cu₂(L¹)₂(tmeda)] (L¹= [N(SiMe₃)(2,6-Me₂C₆H₃)]⁻)⁻ 及[{Cu(tmeda)₂}{Cu(L{U+207F})₂}] (L{U+207F} = [N(R')(2,6-R₂C₆H₃)]⁻: n = 2, R = Pr{U+2071}, R' = SiMe₃; n = 3, R = Me, R' = SiBu{U+1D57}Me₂; n = 4, R = Pr{U+2071}, R' = SiBu{U+1D57}Me₂; n = 5, R = Me, R' = C₆F₅; n = 6, R = Pri, R' = C₆F₅)。另外,銅碘化物與兩倍的苯胺基鉀絡合物反應[KN(R')(2,6-R₂C₆H₃)] 生成一價銅絡合物 [(tmeda)KCu(L²)₂] (L² = [N(SiMe₃)(2,6-Pr{U+2071} ₂C₆H₃)]) 及 [(tmeda)₂KCu(L⁶)₂] (L⁶ = [N(C₆F₅)(2,6-Pr{U+2071} ₂C₆H₃)]。 / 第三章描述了苯胺基一價銅絡合物跟三苯基膦的氧化反應研究,其中研究不同反應條件,包括反應溫度、氧含量及催化物比例對氧化反應的影響。 / 第四章總結了本研究的成果,同時簡單討論了本課題未來的研究方向。 / The present research work focuses on the synthesis, structure and oxygenation reactivity of a series of copper(I) complexes supported by [N(R')(2,6-R₂C₆H₃)]⁻ (R = Me, Pri ; R' = SiMe₃, SiBu{U+1D57}Me₂, C₆F₅) ligands. / Chapter one gives an overview on the chemistry of metal amides. A brief introduction to copper-dioxygen chemistry is also presented. / Chapter two describes the synthesis and structural characterisation of copper(I) anilides. A series of anilido ligands of the type [N(R')(2,6-R₂C₆H₃)]⁻ (R = Me, Pr{U+2071} ; R' = SiMe₃, SiBu{U+1D57}Me₂, C₆F₅) and tmeda (N,N,N',N'-tetramethylethylenediamine) were employed in our studies. Reactions of CuX (X = Cl, I) with alkali-metal salts of the [N(R')(2,6-R₂C₆H₃)]⁻ ligands yielded the corresponding copper(I) complexes of the type [Cu₂(L¹)₂(tmeda)] (L¹= [N(SiMe₃)(2,6-Me₂C₆H₃)]⁻) or [{Cu(tmeda)₂}{Cu({U+207F})₂}] (L{U+207F} = [N(R')(2,6-R₂C₆H₃)]⁻: n = 2, R = Pr{U+2071}, R' = SiMe₃; n = 3, R = Me, R' = SiBu^(t)Me₂; n = 4, R = Pri, R' = SiBu{U+1D57}Me₂; n = 5, R = Me, R' = C₆F₅; n = 6, R = Pri, R' = C₆F₅). Moreover, reactions of CuI with two equivalents of potassium salts of the [N(R')(2,6-R₂C₆H₃)]⁻ ligands gave copper(I) complexes of the type [(tmeda)KCu(L²)₂] (L₂ = [N(SiMe₃)(2,6-Pr{U+2071} ₂C₆H₃)]) and [(tmeda)₂KCu(L⁶)₂] (L⁶ = [N(C₆F₅)(2,6-Pr{U+2071} ₂C₆H₃)]. / Chapter three deals with the oxygenation reactivity of the copper(I) anilido complexes prepared in this work. The reactions of copper(I) complexes 17-24 with dioxygen led to the conversion of triphenylphosphine to triphenylphosphine oxide. The oxo-transfer reaction was studied under different reaction conditions, such as reaction temperature, oxygen content, and [PPh₃]:[complex] ratio. / Chapter four summarises the results of this research work. An outlook on future directions of this research project is also described in this chapter. / 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. / Chen, Yat Kit. / "November 2012." / Thesis (M.Phil.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references. / Abstracts also in Chinese. / Abstract --- p.i / 摘要 --- p.iii / Acknowledgement --- p.iv / Abbreviations --- p.vii / List of Compounds --- p.x / Chapter Chapter 1 - --- An Overview on Late Transition Metal Amides and Copper-Dioxygen Chemistry / Chapter 1.1 --- General Background --- p.1 / Chapter 1.2 --- An Introduction to Late Transition Metal Amides --- p.1 / Chapter 1.3 --- An Introduction to Copper-Dioxygen Chemistry --- p.4 / Chapter 1.4 --- Objectives of This Work --- p.6 / Chapter 1.5 --- References for Chapter 1 --- p.7 / Chapter Chapter 2 - --- Synthetic and Structural Studies of Copper Anilides / Chapter 2.1 --- A General Overview on Anilido Complexes --- p.11 / Chapter 2.2 --- Aims of Our Study --- p.22 / Chapter 2.3 --- Results and Discussion / Chapter 2.3.1 --- Aniline Precursors and Their Alkali Metal Derivatives / Chapter 2.3.1.1 --- Synthesis of Aniline Precursors HL{U+207F} (n = 1-6) --- p.23 / Chapter 2.3.1.2 --- Synthesis of Alkali Metal Derivatives of L{U+207F} (n = 1-6) --- p.25 / Chapter 2.3.1.3 --- Physical Properties of Compounds 7-16 --- p.26 / Chapter 2.3.1.4 --- Molecular Structures of Compounds 7-16 --- p.33 / Chapter 2.3.2 --- Synthesis and Structures of Copper Anilides / Chapter 2.3.2.1 --- Synthesis of Copper(I) Complexes of L{U+207F}(n = 1-6) --- p.62 / Chapter 2.3.2.2 --- Physical Properties of Compounds 17-24 --- p.65 / Chapter 2.3.2.3 --- Molecular Structures of Compounds 17-24 --- p.70 / Chapter 2.3.3 --- Electrochemical Studies --- p.100 / Chapter 2.4 --- Experimentals for Chapter 2 --- p.109 / Chapter 2.5 --- References for Chapter 2 --- p.120 / Chapter Chapter 3 - --- Oxygenation Reactivity Studies / Chapter 3.1 --- A General Review on Oxygenation Copper-Dioxygen Chemistry --- p.128 / Chapter 3.2 --- Aims of Our Study --- p.148 / Chapter 3.3 --- Results and Discussion --- p.149 / Chapter 3.4 --- Experimentals for Chapter 3 --- p.153 / Chapter 3.5 --- References for Chapter 3 --- p.155 / Chapter Chapter 4 - --- Summary and Future Directions --- p.161 / Chapter Appendix A --- General Procedure, Physical Measurements and X-ray Diffraction Analysis --- p.164 / Chapter Appendix B --- NMR Spectra of Compounds --- p.166 / Chapter Appendix C --- Selected Crystallographic Data --- p.191
68

Synthesis and structures of transition metal complexes derived from a pentafluorophenyl substituted 2-pyridyl amido ligand.

January 2009 (has links)
Lai, Yin Man. / Thesis submitted in: November 2008. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references. / Abstracts in English and Chinese. / ACKNOWLEDGEMENT --- p.I / ABSTRACT --- p.II / 摘要 --- p.IV / ABBREVIATIONS --- p.V / LIST OF COMPOUNDS --- p.VI / TABLE OF CONTENTS --- p.IX / Chapter CHAPTER 1 --- A 2-PYRIDYL AMIDO LIGAND CONTAINING A PENTAFLUOROPHENYL SUBSTITUENT --- p.1 / Chapter 1. l --- General Background --- p.1 / Chapter 1.2 --- Examples of Amido Ligands --- p.3 / Chapter 1.3 --- An overview on Amido Ligands Containing Electron-withdrawing Substituents --- p.5 / Chapter 1.4 --- Objectives of This Work --- p.7 / Chapter 1.5 --- Results and Discussion --- p.8 / Chapter 1.5.1 --- Preparation of HLC6F5 (1) and its Potassium Derivatives --- p.8 / Chapter 1.5.2 --- Physical Characterization of Compounds 1-3 --- p.10 / Chapter 1.5.3 --- Molecular Structures of Compounds 2 and 3 --- p.13 / Chapter 1.6 --- Experimentals for Chapter 1 --- p.19 / Chapter 1.7 --- References for Chapter 1 --- p.22 / Chapter CHAPTER 2 --- "ZIRCONIUM(IV), VANADIUM(III) AND CHROMIUM(III) COMPLEXES DERIVED FROM THE [N(C6F5)(2-CsH3N-6-ME)] LIGAND" --- p.27 / Chapter 2.1 --- "An Overview on Zr(IV), V(III) and Cr(III) Complexes Supported by 2-Pyridyl Amido Ligands" --- p.27 / Chapter 2.2 --- Recent Results from our Group --- p.32 / Chapter 2.3 --- Objectives of this work --- p.33 / Chapter 2.4 --- "Synthesis and Structures of Tris(amido) Complexes of Zr(IV), V(III) and CR(III)" --- p.34 / Chapter 2.4.1 --- "Synthesis of [Zr(LC6F5)3(Cl) ´Ø C7H8] (4), V(LC6F5)3 (5) and [Cr(LC6F5)3] (6)" --- p.34 / Chapter 2.4.2 --- Molecular Structures of [Zr(LC6F5)3(Cl)´ØC7H8] (4)f and [Cr(LC6F5)3] (6) --- p.37 / Chapter 2.5 --- Experimentals for Chapter 2 --- p.43 / Chapter 2.6 --- References for Chapter 2 --- p.45 / Chapter CHAPTER 3 --- "MANGANESE(II), IRON(II), COBALT(II) AND NICKEL(II) COMPLEXES OF THE [N(C6F5)(2-C5H3N-6-ME)] LIGAND" --- p.49 / Chapter 3.1 --- A Brief Review on Amides of the Late Transition Metals --- p.49 / Chapter 3.2 --- Examples of Late Transition Metal Complexes Supported by 2-Pyridyl Amido Ligands --- p.51 / Chapter 3.3 --- Objectives of our studies --- p.53 / Chapter 3.4 --- "Synthesis and Structures of Bis(amido) Complexes of Mn(II), Fe(II), Co(II) and NI(II)" --- p.54 / Chapter 3.4.1 --- "Synthesis of [M(LC6F5)2(tmeda)] (M = Mn (7), Fe (8), Co (9), Ni (10)]" --- p.54 / Chapter 3.4.2 --- Molecular Structures of Complexes 7-10 --- p.57 / Chapter 3.5 --- "Synthesis, Structure and Reactivity of a Mono(amido) Fe(II) Complex" --- p.61 / Chapter 3.5.1 --- Synthesis of [Fe(LC6F5)(CI)(tmeda)](11) --- p.61 / Chapter 3.5.2 --- Physical Characterization of Compound 11 --- p.62 / Chapter 3.5.3 --- Molecular Structures of Compound 11 --- p.62 / Chapter 3.5.4 --- Reactivity Studies of [Fe(LC6F5)(Cl)(tmeda)] (11) --- p.66 / Chapter 3.6 --- Synthesis of Fe(III) Tri(amido) Complex --- p.69 / Chapter 3.7 --- Experimentals for Chapter 3 --- p.70 / Chapter 3.8 --- References for Chapter 3 --- p.73 / Chapter CHAPTER 4 --- SUMMARY OF THE PRESENT RESEARCH WORK --- p.75 / TABLE OF APPENDIX --- p.79 / "General Procedures, Physical Measurements and X-Ray Structural Analysis" --- p.80 / 1HNMR of HCC6F5(1) --- p.82 / 13CNMR of HLC6F5(1) --- p.83 / 19FNMR of HLC6F5(1) --- p.84 / 1HNMR of [K(LC6F5)(tmeda)]2 (2) --- p.85 / 13CNMR OF [K(LC6F5)(tmeda)]2 (2)) --- p.86 / 19FNMR of [K(LC6F5)(TMEDA)]2 (2)) --- p.87 / 1HNMR of [K(LC6F5)(thf)2]2 (3) --- p.88 / 13CNMR of [K(LC6F5)(thf)2]2 (3) --- p.89 / 19FNMR OF [K(LC6F5)(THF)2]2 (3) --- p.90 / 1HNMR of Zr(LC6F5)3(Cl).(C7H8)] (4) --- p.91 / Selected crystallographic data of complexes 2 and 3 --- p.94 / Selected crystallographic data of complexes 4 and 6 --- p.95 / Selected crystallographic data of complexes 7 and 8 --- p.96 / Selected crystallographic data of complexes 9 and 10 --- p.97 / Selected crystallographic data of complex 11 --- p.98
69

Studies of the reactivities of organometallic complexes containing platinum(IV)-oxygen bonds /

Williams, Burke Scott. January 2000 (has links)
Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 179-189).
70

Identification of hydrogen-containing defects in the III-V nitrides and in Si from advanced applications of vibrational spectroscopy /

Weinstein, Marcie G. January 2000 (has links)
Thesis (Ph. D.)--Lehigh University, 2000. / Includes bibliographical references and vita.

Page generated in 0.0814 seconds