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by Lee Hung Kay. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1995. / Includes bibliographical references. / Table of Contents --- p.i / Acknowledgements --- p.vi / Abstracts --- p.vii / Abbreviations --- p.ix / Chapter CHAPTER I. --- GENERAL INTRODUCTION / Chapter I.1 --- A Brief Review on the Background of Organometallic Chemistry --- p.1 / Chapter I.2 --- Stability of Organotransition Metal Complexes --- p.2 / Chapter I.3 --- Decomposition Pathways of Transition Metal σ Hydrocarbyls --- p.5 / Chapter I.4 --- Preparation of Transition Metal σ-Alkyl Complexes --- p.10 / Chapter I.5 --- A Survey on the Use of Functionalized Alkyl and Aryl Ligands in Synthesis of Transition Metal σ-Hydrocarbyls --- p.15 / Chapter I.6 --- 2-(Trimethylsilyl)methylpyridine (3) and 2-Bis(trimethylsilyl)- methylpyridine (4) as Ligand Precursors --- p.20 / Chapter I.7 --- A Brief Review of Previous Results on Synthesis of Metal Alkyl Complexes Using (1) and (2) as Ligands --- p.23 / Chapter I.8 --- Objective of This Work --- p.28 / Chapter I.9 --- References for Chapter I --- p.29 / Chapter CHAPTER II. --- "SYNTHESIS, STRUCTURES AND REACTIVITY OF IRON(n) AND COBALT(II) DIALKYL COMPLEXES" / Chapter II. 1 --- Introduction / Chapter II. 1.1 --- Synthesis of Iron(II) and Cobalt(II) Alkyl Complexes --- p.34 / Chapter IL1.1.1 --- Iron(II) Alkyl Complexes --- p.34 / Chapter II.1.1.2 --- Cobalt(II) Alkyl Complexes --- p.41 / Chapter II.1.2 --- Reactions of Transition Metal Alkyl Complexes with Protic Reagents and Halogens --- p.45 / Chapter II. 1.3 --- The Chemistry of Transition Metal Alkoxides and Thiolates 一 A Brief Review --- p.48 / Chapter II.2 --- Results and Discussion / Chapter II.2.1 --- "Synthesis of Homoleptic Iron(II) and Cobalt(II) Dialkyl Complexes [M {C(SiMe3)2C5H4N-2} 2] (M=Fe 55,Co 56)" --- p.51 / Chapter II.2.2 --- Attempted Reaction of [FeCl2(PPh3)2] with [{R2Li}2] --- p.52 / Chapter II.2.3 --- Attempted Synthesis of Monoalkyliron(II) Complexes --- p.53 / Chapter II.2.4 --- "Synthesis of Homoleptic Iron(II) and Cobalt(II) Dialkyl Complexes [M{(CHSiMe3)C9H6N-8}2] (M = Fe57, Co 58)" --- p.54 / Chapter II.2.5 --- Molecular Structures of [M{C(SiMe3)2C5H4N-2}2] (M =Fe 55.Co 56) and [Co{(CHSiMe3)C9H6N-8}2] (58) --- p.56 / Chapter II.2.6 --- Spectroscopic and Magnetic Properties of Compounds 55-58 --- p.63 / Chapter II.2.7 --- Electrochemistry of [Co(R2)2] (56) and [Co(R3)2] (58) --- p.66 / Chapter II.2.8 --- "Reactivities of [M{C(SiMe3)2C5H4N-2}2] (M = Fe55, Co 56)" --- p.70 / Chapter II.3 --- Experimentals for Chapter II --- p.83 / Chapter II.4 --- References for Chapter II --- p.86 / Chapter CHAPTER III. --- SYNTHESIS AND STRUCTURES OF DIALKYL COMPLEXES OF NICKEL(II) AND PALLADIUM(II) / Chapter III. 1 --- Introduction / Chapter III. 1.1 --- Nickel(II) Alkyl Complexes 一 A General Survey --- p.91 / Chapter III.1.1.1 --- η5-Cyclopentadienylnickel Alkyl and Aryl Complexes --- p.91 / Chapter III.1.1.2 --- Nickel Dialkyls --- p.96 / Chapter III. 1.2 --- Palladium(II) Alkyl Complexes ´ؤ A General Survey --- p.99 / Chapter III.1.2.1 --- Palladium Dialkyls --- p.99 / Chapter III. 1.2.2 --- Cyclopalladated Compounds --- p.101 / Chapter III.2 --- Results and Discussion / Chapter III.2.1 --- Synthesis of Nickel(II) Alkyl Complexes --- p.104 / Chapter III.2.1.1 --- Reactions of [{R1Li(Et2O)}2] and [{R2Li}2] with Nickelocenes ´ؤ Synthesis of η5 - Cyclopentadienylnickelalkyl Complexes (78-80) --- p.104 / Chapter III.2.1.2 --- Synthesis of the Substituted Nickelocene [Ni{{466}5- C5H3(SiMe3)2}2] (81) --- p.106 / Chapter III.2.1.3 --- Spectroscopic Properties of Compounds 78-80 --- p.107 / Chapter III.2.1.4 --- Molecular Structures of [(η5- C5H5)Ni{C(SiMe3)2C5H4N-2}] (78) and [{(η5- C5H5)Ni{CH(SiMe3)C5H4N-2}}2] (80) --- p.110 / Chapter III.2.1.5 --- "Reactions of [{R2Li}2] with NiCl2 and [NiCl2L2] (L2 = TMEDA, 2PPh3) ´ؤ Synthesis of Nickel Dialkyl Complex [Ni{C(SiMe3)2C5H4N-2}2] (82)" --- p.115 / Chapter III.2.1.6 --- Molecular Structure of [Ni{C(SiMe2)2C5H4N- 2}2] (82) --- p.118 / Chapter III.2.1.7 --- Spectroscopic Properties of [Ni{C(SiMe3)2C5H4N-2}2] (82) --- p.121 / Chapter III.2.1.8 --- Electrochemistry of [Ni{C(SiMe3)2C5H4N-2}2] (82) --- p.122 / Chapter III2.1.9 --- Reactivities of Ni[C(SiMe3)2C5H4N-2]2 (82) --- p.124 / Chapter III.2.1.10 --- "Reactions of [{R2Li}2] with [NiCl2(diphos)] [diphos = 1,2-bis(diphenylphosphino)ethane]" --- p.125 / Chapter III.2.1.11 --- Molecular Structure of [Ni{C(SiMe3)2C5H4N- 2}{5-(2'-C5H4NC(SiMe3)2C5H4N-2- CH(SiMe3)2}Cl] (83) --- p.127 / Chapter III.2.1.12 --- "Reactions of [{R1Li(Et2O)}2] and [R5Li] [-R5 = -CH2C5H4N-2] with NiCl2 and [NiCl2L2] (L2 = TMEDA, 2PPh3)" --- p.130 / Chapter III.2.1.13 --- Molecular Structure of [{CH(SiMe3)C5H4N- 2}2] (86) --- p.136 / Chapter III.2.2 --- Synthesis of Palladium(II) Alkyl Complexes --- p.139 / Chapter III.2.2.1 --- "Reactions of [{R2Li}2] with [PdX2L2] (L = PPh3, Et2S; X=Cl, Br) ´ؤ Synthesis of [Pd(R2)2] (88) and [Pd(R2)(PPh3)X] [X 二 Cl 89, Br 90]" --- p.139 / Chapter III.2.2.2 --- "Molecular Structures of Compounds [P'd{C(SiMe3)2C 5H 4N-2}2] (8 8), [Pd{C(SiMe3)2C5H4N-2}(PPh3)Cl] (89)，and [Pd{C(SiMe2)2C5H4N-2}(PPh3)Br] (90)" --- p.140 / Chapter III.2.2.3 --- Spectroscopic Properties of Compounds 88-90 --- p.146 / Chapter III.2 2.4 --- Electrochemistry of [Pd{C(SiMe3)2C5H4N-2}2] (88) --- p.147 / Chapter III.2.2.5 --- "Studies on Stereo specificity of the Reactions between [{R2Li}2] and [PdX2(PPh3)2] (X = Cl, Br)" --- p.150 / Chapter III.2.2.6 --- Attempted Synthesis of [Pd(R1)2] and [Pd(R1)(PPh3)Cll --- p.152 / Chapter III.2.2.7 --- Attempted Synthesis of [{Pd(R2)Cl}2]via Intramolecular C-H Activation --- p.153 / Chapter III.2.2.8 --- Molecular Structure of [{CH(SiMe3)2C5H4N- 2}2PdCl2} (91) --- p.154 / Chapter III.3 --- Experimentals for Chapter III --- p.157 / Chapter III.4 --- References for Chapter III --- p.165 / Chapter CHAPTER IV. --- SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF ZIRCONIUM(IV) AND HAFNIUM(IV) ALKYL COMPLEXES / Chapter IV. 1 --- Introduction --- p.169 / Chapter IV. 1.1 --- Homoleptic and Heteroleptic Complexes --- p.170 / Chapter IV. 1.2 --- Organo-Zirconium(IV) and -Hafnium(IV) Compounds Containing Functionalized Alkyl Ligands --- p.177 / Chapter IV.2 --- Results and Discussion / Chapter IV.2.1 --- "Synthesis of Zirconium(IV) and Hafnium(IV) Dialkyl Dichloride Compounds [M(R2)2C12] (M = Zr 103,Hf 104" --- p.181 / Chapter IV.2.2 --- Attempted Synthesis of Titanium(IV) Alkyl by the Reaction of TiCl4 with [{R2Li}2] --- p.182 / Chapter IV.2.3 --- Attempted Synthesis of Zirconium(IV) and Hafnium(IV) Alkyls with -R 1[= -CH(SiMe3)C5H4N-2] as Ligand --- p.182 / Chapter IV.2.4 --- Molecular Structure of [Zr{C(SiMe3)2C5H4N- 2}2C12] (103) --- p.183 / Chapter IV.2.5 --- Spectroscopic Properties of {C(SiMe3)2C5H4N- 2}2C12] (M = Zr 103，Hf 104) --- p.187 / Chapter IV.3 --- Experimentals for Chapter IV --- p.188 / Chapter IV.4 --- References for Chapter IV --- p.190 / Chapter CHAPTER V. --- COMPARISON OF BONDING PARAMETERS AMONG METAL ALKYL COMPLEXES WHICH CONTAIN ALKYL LIGANDS -R2 --- p.193 / References for Chapter V --- p.201 / APPENDIX I / Chapter A. --- General Procedures --- p.202 / Chapter B. --- Physical and Analytical Measurements --- p.202 / APPENDIX II / Magnetic Moment Measurements --- p.205 / APPENDIX III / "Table A-l. Selected Crystallographic Data for Compounds 55, 56, 58,and63" --- p.207 / "Table A-2. Selected Crystallographic Data for Compounds 78, 80，82 and83" --- p.208 / "Table A-3. Selected Crystallographic Data for Compounds 86, 88, 89 and90" --- p.209 / Table A-4. Selected Crystallographic Data for Compounds 91 and 103.… --- p.210

Call number: LD2668 .T4 1965 R883 / Master of Science

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

An atomically thin film of semiconducting transition metal dichalcogenides (TMDCs) is emerging as a class of key materials in chemistry and physics due to their remarkable chemical and electronic properties. The TMDCs are layered materials with weak out-of-plane van der Waals (vdW) interaction and strong in-plane covalent bonding enabling scalable exfoliation into two-dimensional (2D) layers of atomic thickness. The growth techniques to prepare these 2D TMDC materials in high yield and large scale with high crystallinity have attracted intensive attention recently because of the new properties and potentials in nano-elctronic, optoelectronic, spintronic and valleytronic applications. In this thesis, I develop methods for the chemical synthesis of 2D TMDCs films. The relevant growth mechanism and material characteristics of these films are also investigated. Molybdenum disulfide (MoS2) is synthesized by using molybdenum trioxide (MoO3) and sulfur (S) powder as the precursor. The films are formed on substrate pre-treated with reduced graphene oxide as the catalyst. However, this method cannot be extended to other TMDC materials such as molybdenum diselenide (MoSe2) and tungsten diselenide (WSe2) because reduced graphene oxide (rGO) reacts with selenium to form alloy materials rather than TMDC films. At the same time, the conversion of MoO3 to MoSe2 or that of tungsten trioxide (WO3) to WSe2 without the assistance of hydrogen in the chemical reaction is not thermodynamically feasible because the oxygen in the metal oxide cannot be replaced by selenium due to lower reactivity of the latter. On the other hand, I demonstrate that MoSe2 film can be synthesized directly by using MoSe2 and Se powder. Furthermore, the method of sulfurization or selenization of pre-deposited metal film can be promising due to precise thickness/size controls. Finally, some perspectives on the engineering challenges and fabrication methods of this family of materials will be given. / published_or_final_version / Physics / Master / Master of Philosophy

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