This thesis is dedicated to developing novel charged Pt(II) complexes and exploring their applications in electroluminescence, bio-imaging and the preparation of soft salts. At the beginning, a brief introduction about the development of ionic transition metal complexes and an overview of their applications in electroluminescence, bio-imaging and soft salts are presented. In chapter 2, a series of anionic Pt(II) complexes were successfully synthesized and fully characterized for their application in electroluminescence with relatively small current density. All the complexes show highly intense emission from blue to red in the solid state but is almost non-emissive in solution. The obtained single crystal data show that the anionic Pt(II) complexes exhibit very large Pt-Pt separation of over 10 Å in the crystal packings due to the bulky counterion [N(n-C4H9)4]+. The strong interactions between adjacent [Pt(C^N)(CN)2]- is thus absent in the solid state and this is considered as the main reason for the different properties in solution and solid state of these anionic complexes. This kind of Pt(II) anionic complexes has also found application in electroluminescence with relatively small current density. A series of novel water-soluble cationic Pt(II) complexes have also been designed and synthesized in chapter 3. Their photophysical properties in both water solution and solid state were investigated. Some of the cationic Pt(II) complexes have been selected to be applied in cell imaging in both live human hepatoma cells (BEL-7402) and mouse embryonic fibroblast (MEF) cells. The results show that these complexes have a much higher cellular uptake in BEL-7402 cells (tumor cells) than in MEF cells (normal cells), indicating these complexes are promising probes for tumor cell imaging. All of the cationic Pt(II) complexes show very low cytotoxicity at low concentration and the cell viability is still assessed to be high even when the concentration increases to 10 μM. The localization of the complexes turned out to be in the cytoplasm and accumulate near the cell nucleus. Attempts have been made to obtain efficient deep-red or NIR Pt(II) complexes by taking advantages of the Pt-Pt interactions in chapter 4. Two Pt(II) soft salts, SS1 and SS2 with bright emission at 674 and 718 nm, have been successfully prepared and characterized. The crystal packing shows a short separation between the two Pt atoms of 3.476 Å and the average distance of two planes of the cyclometalated ligands is 3.360 Å, indicating the existence of strong intramolecular Pt-Pt and π-π interactions. It is the first examples of Pt(II) soft salts bearing strong Pt-Pt interactions and π-π stacking and this has opened a versatile and facile avenue to prepare efficient NIR Pt(II) emitters by taking advantages of the Pt-Pt interactions. SS2 shows different emission in PEG with different concentration and excitation wavelength, indicating their potential application in optical data storage. The electrochromic properties of SS2 have also been investigated considering that the soft salt consists of ions with opposite charges, which suggests the soft salt could be promising candidate for electrochromic and optoelectronic material. The Pt(II) soft salt has also been used as NIR in-vivo imaging probe. Chapters presents the concluding remarks and points out some further work that could be done in the future. The experimental details are displayed in Chapter 6.

published_or_final_version / abstract / Chemistry / Doctoral / Doctor of Philosophy

Wu Yuen Sze. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves 98-107). / Abstracts in English and Chinese. / Table of contents --- p.i / Acknowledgements --- p.iv / Abstract --- p.v / List of compounds --- p.vi / Abbreviations --- p.x / Chapter Chapter 1 --- Synthesis and Structures of Low-valent Group14 Organometallic Compounds --- p.1 / Chapter 1.1 --- General apects of low-valent group 14 compounds --- p.1 / Chapter 1.2 --- Structures of germylenes and stannylenes --- p.3 / Chapter 1.3 --- Tetravalent group 14 Metal amides --- p.7 / Chapter 1.4 --- Objectives --- p.11 / Chapter 1.5 --- Results and Discussion --- p.12 / Chapter 1.5.1 --- Synthesis of germanium(II) compound [Ge{C(C5H4N- 2)C(Ph)N(SiMe3)2}{N(SiMe3)C(Ph)C(SiMe3)(C5H4N- 2)}] (29) --- p.12 / Chapter 1.5.2 --- Synthesis of tin(II) amide [Sn{N(SiMe3)C(Ph)C- (SiMe3)(C5H4N-2)}2] (30) --- p.14 / Chapter 1.5.3 --- Synthesis of tin(IV)(amide)dichloride [Sn{N(SiMe3)C- (Ph)C(SiMe3)(C5H4N-2)}2Cl2] (31) --- p.15 / Chapter 1.5.4 --- Spectroscopic Properties of Compounds 29-31 --- p.16 / Chapter 1.5.5 --- Molecular Structure of [Ge{C(C5H4N-2)C(Ph)N(Si- Me3)2}{N(SiMe3)C(Ph)C(SiMe3)C(C5H4N-2)}] (29) --- p.21 / Chapter 1.5.6 --- Molecular structure of [Sn{N(SiMe3)C(Ph)C(SiMe3)- (C5H4N-2)}2] (30) --- p.25 / Chapter 1.5.7 --- Molecular structure of [Sn{N(SiMe3)C(Ph)C(SiMe3)- (C5H4N-2)}2C12] (31) --- p.28 / Chapter Chapter 2 --- Synthesis and Structure of Group 14 Metal- Chalcogenones --- p.32 / Chapter 2.1 --- Multiple bond between group 14 metals and chalcogens --- p.32 / Chapter 2.2 --- Results and Discussion --- p.39 / Chapter 2.2.1 --- "Synthesis of germane- and stannane-chalcogenones [(RI)(R1.)Ge=E], [E = S 59, Se 60], [(R1)2Sn=S] (61)， [(R1)(R1.)Sn=Se] (62)" --- p.39 / Chapter 2.2.2 --- Spectroscopic properties of compounds 59-62 --- p.41 / Chapter 2.2.3 --- Molecular structure of [{N(SiMe3)C(Ph)C(SiMe3)- (C5H4N-2)}2Sn=S] (61) --- p.46 / Chapter 2.2.4 --- "Molecular structure of [{N(SiMe3)2C(Ph)C(C5H4N-2)}- {N(SiMe3)C(Ph)C(SiMe3)(C5H4N-2)}M=E] [M = Ge, E =S 59，Se 60; M = Sn,E = Se 62]" --- p.52 / Chapter Chapter 3 --- Reactivity of Low-valent Group 14 Organometallics Compounds --- p.59 / Chapter 3.1 --- Introduction --- p.59 / Chapter 3.1.1 --- Lewis-base behavior --- p.60 / Chapter 3.1.2 --- Lewis-acid behavior --- p.63 / Chapter 3.1.3 --- Oxidative-addition (or insertion) reactions --- p.65 / Chapter 3.2 --- Results and Discussion --- p.69 / Chapter 3.2.1 --- Lewis acid base behavior of [Sn(R2)2] (27) --- p.69 / Chapter 3.2.1.1 --- "Reaction of [Sn(R2)2] (27) with group 11 metal derivatives (M = Ag, X = Cl 91,I 92,SCN 93，CN94; M = Cu, X = Cl 95，I 96)-Synthesis of [(R2)2Sn→(μ- MX)]2" --- p.69 / Chapter 3.2.2 --- Oxidative-addition (or insertion) reaction of tin(II) compounds --- p.73 / Chapter 3.2.2.1 --- Reaction of AgNCO with [Sn(R2)2] (27) 一 Synthesis of [(R2)2Sn(NCO)2](97) --- p.73 / Chapter 3 .2.3 --- Spectroscopic properties of compounds 91-97 --- p.74 / Chapter 3.2.4 --- Molecular structure of [{CH(SiMe3)C9H6N-8}2Sn→(μ- AgCl)]2 (91) --- p.80 / Chapter 3.2.5 --- Molecular structure of [{CH(SiMe3)C9H6N-8}2Sn- (NCO)2] (97) --- p.85 / Appendix I / Chapter A. --- Experimental procedures for chapter 1 --- p.87 / Chapter B. --- Experimental procedures for chapter 2 --- p.90 / Chapter C. --- Experimental procedures for chapter 3 --- p.93 / Appendix II / Chapter A. --- References for chapter 1 --- p.98 / Chapter B. --- References for chapter 2 --- p.102 / Chapter C. --- References for chapter 3 --- p.104 / Appendix III / Chapter A. --- General procedures --- p.106 / Chapter B. --- Physical and analytical measurements --- p.106 / Appendix IV / Table A.l. Selected crystallographic data for compounds 29，30，31 --- p.109 / Table A.l. Selected crystallographic data for compounds 59，60，61 --- p.110 / "Table A.l. Selected crystallographic data for compounds 62, 91，97" --- p.111

by Man-Hang Chan. / Thesis submitted in 1997. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references. / Abstract also in Chinese. / Contents --- p.i / Acknowledgements --- p.iii / Abstract --- p.iv / 摘要 --- p.v / Abbreviations --- p.vi / Chapter CHAPTER I --- INTRODUCTION / Chapter I.1 --- "Organometallic chemistry of group 11 elements (Cu, Ag, Au)" --- p.1 / Chapter I.1.1 --- Organocopper(I) compounds --- p.3 / Chapter I.1.2 --- Organosilver(I) compounds --- p.5 / Chapter I.1.3 --- Organogold(I) compounds --- p.7 / Chapter I.2 --- Dimethylpyrazine as a ligand precursor --- p.9 / Chapter I.3 --- Objective of this work --- p.11 / Chapter I.4 --- References --- p.13 / Chapter CHAPTER II --- METALLATION OF DIMETHYLPYRAZINE / Chapter II. 1 --- Introduction --- p.17 / Chapter II. 1.1 --- N-functionalized alkyl ligands --- p.17 / Chapter II. 1.2 --- Synthetic methods --- p.18 / Chapter II. 1.3 --- Synthesis of alkyl ligands with N-functionality --- p.20 / Chapter II.2 --- Results and discussion --- p.22 / Chapter II.2.1 --- "Metallation of 2,3-dimethylpyrazine" --- p.22 / Chapter II.2.2 --- "Metallation of 2,5-dimethylpyrazine" --- p.26 / Chapter II. 2.3 --- "Metallation of 2,6-dimethylpyrazine" --- p.29 / Chapter II.2.4 --- Characterization of compounds --- p.34 / Chapter II. 3 --- Experimental --- p.51 / Chapter II. 4 --- References --- p.57 / Chapter CHAPTER III --- SYNTHESIS AND STRUCTURE OF COPPER(I)AND SILVER(I) COMPOUNDS / Chapter III.l --- Introduction --- p.59 / Chapter III.1.1 --- Synthesis of Group 11 metal alkyl complexes --- p.59 / Chapter III.1.2 --- Structures of Group 11 metal alkyl complexes --- p.61 / Chapter III.2 --- Results and Discussions --- p.63 / Chapter III.2.1.1 --- Synthesis of [Cu{CH(ButMe2Si)C5H4N-2}]4 --- p.63 / Chapter III.2.1.2 --- Reaction of [PictLi] with AgBF4 and AI --- p.64 / Chapter III.2.1.3 --- Characterization of compounds --- p.65 / Chapter III.2.1.4 --- Molecular structure of[Cu{CH(ButMe2Si)C5H4N-2}]4 --- p.67 / Chapter III.2.2 --- Synthesis of [Cu{C(Ph)(SiMe3)C5H4N -2}]2 --- p.73 / Chapter III.2.3.1 --- Reaction of CuI with [DZ´حLi2] and [DZLi2] --- p.73 / Chapter III.2.3.2 --- Reaction of CuI with [DZ'Li] --- p.75 / Chapter III.2.4 --- Characterization of compounds --- p.75 / Chapter III.2.5 --- Attempted reaction of [Q'Li(TMEDA)] with CuCI and CuCl2 --- p.77 / Chapter III. 3 --- Experimental --- p.78 / Chapter III. 4 --- References --- p.87 / Appendix --- p.89

本論文工作主要包括三部分: (i) 含吡啶基-1-氮雜烯丙基配體的二价鍺氯化物的反應研究； (ii) 含吡啶基-1-氮雜烯丙基配體的一价鍺二聚體的合成及反應研究; (iii) 膦亞胺配體衍生的低价態第十四族金屬復合物及金屬亞乙烯的合成與反應研究。 / 第一章描述含吡啶基-1-氮雜烯丙基配位體的二价鍺氯化物66的反應。化合物66與Na[M(η⁵-C₅H₅)(CO)₃]2DME (M = Mo or W)反應，得到含鍺(II)-金屬單鍵的異核雙金屬鍺亞乙烯化合物76及77。化合物66與環戊二烯鈉反應生成了環戊二烯基取代的鍺烯。作為路易斯鹼，化合物66與大位阻硼烷的反應得到研究。化合物66與B(C₆F₅)₃反應，得到路易斯酸-鹼加合物79。此外，化合物66與三价氯化鎵及三价氯化銦進行的配體轉移反應也得到研究。另外，化合物66與水的反應產生[{HNC(Ph)CH(C₅H₄N-2)}GeCl] (82)。 / 第二章描述化合物66的還原化學。二价鍺氯化物66與過量鎂反應得到 [N(SiMe₃)C(Ph)C(SiMe₃) (C₅H₄N-2)Mg(μ-Cl)(THF)]₂ (110)和[C(Ph)C(SiMe₃)(C₅H₄N-2)]₂Ge₂ (111)的混合物。而其與過量金屬鋰反應則得到一价鍺二聚體[C(Ph)C(SiMe₃)(C₅H₄N-2)]₂Ge₂ (111)及[N(SiMe₃)C(Ph)C(SiMe₃) (C₅H₄N-2)]₂Ge₂ (112)。化合物66與等當量石墨鉀反應，主要得到一价鍺二聚體112。化合物112與偶氮苯反應得到鍺聯氨衍生物[PhNGe{N(SiMe₃) C(Ph)C(SiMe₃)(C₅H₄N-2)}]₂₋(113)。化合物112的路易斯鹼性得到研究。化合物112與一當量九羰基二鐵反應生成新型不對稱一价鍺二聚體[{N(SiMe₃)C(Ph)C(SiMe₃)(C₅H₄N-2)(Fe(CO)₄)- Ge-Ge{N(SiMe₃)C(Ph)C(SiMe₃)(C₅H₄N-2)}](114)，而其與兩當量九羰基二鐵反應則得到[{N(SiMe₃)C(Ph)C(SiMe₃)(C₅H₄N-2)Fe(CO)₄)Ge]₂(115)。此外，二聚體112與硫磺進行反應，得到首個鍺二硫代羧酸酐的鍺類似物。 / 第三章介紹從膦亞胺配體衍生的二价態第十四族金屬復合物的合成，描述了由配體Ph₂P(2-CH₂Py)=NSiMe₃ (119)及H₂C(PPh₂=NSiMe₃)₂ (121)衍生的二价鍺及二价錫化合物的合成。此外，本章研究了半穏定配體Ph₂PCH₂(PPh₂=NSiMe₃) (131)的配位化學。化合物131在Bu[superscript n]Li及Bu[superscript n]₂Mg的作用下金屬化分解反應，分別生成膦亞胺鋰化合物[Li{CH(PPh₂)(PPh₂=NSiMe₃)}(THF)₂] (194)及鎂化合物[Mg{CH(PPh₂)(PPh₂=NSiMe₃)}₂] (193)。化合物194與相應的二价金屬氯化物反應得到1,3-二錫環丁烷196和1,3-二鉛環丁烷200。化合物194與二氯化鍺二噁烷配合物的反應得到新型三核雜環化合物195。此外，化合物196與九羰基二鐵反應，得到膦穏定的錫亞乙烯197。 / 第四章為第一至第三章的總結。 / This thesis is focused on three areas: (i) the reactivities of pyridyl-1-azaallyl germanium(II) chloride; (ii) the synthesis and reactivities of pyridyl-1-azaallyl germanium(I) dimer; (iii) the synthesis and reactivities of low-valent main group 14 metal complexes and metallavinylidenes derived from phosphoranoimines. / Chapter 1 describes the reactivities of pyridyl-1-azaallyl germanium(II) chloride [{N(SiMe₃)C(Ph)C(SiMe₃)(C₅H₄N-2)}GeCl] (66). The reaction of 66 with Na[M(η⁵-C₅H₅)(CO)₃]2DME (M = Mo or W) affords heterobimetallic germylenes 76 and 77 which contain a germanium(II)-metal single bond. A Cp-substituted germylene was prepared from the reaction of 66 with sodium cyclopentadienylide. The Lewis base behavior of 66 toward bulky borane was investigated. Treatment of 66 with B(C₆F₅)₃ leads to the formation of a Lewis acid-base adduct 79. Furthermore, the ligand transfer reaction of 66 with GaCl₃ and InCl₃ were studied. In addition, the reaction of 66 with water affords [{HNC(Ph)CH(C₅H₄N-2)}GeCl] (82). / Chapter 2 describes the reduction chemistry of 66. Treatment of 66 with excess magnesium tunings affords a mixture of products [N(SiMe₃)C(Ph)C(SiMe₃)- (C₅H₄N-2)Mg(μ-Cl)(THF)]₂ (110) and [C(Ph)C(SiMe₃)(C₅H₄N-2)]₂Ge₂ (111). The reaction of 66 with an excess of lithium metals leads to a mixture of germanium(I) dimers [C(Ph)C(SiMe₃)(C₅H₄N-2)]₂Ge₂ (111) and [N(SiMe₃)C(Ph)C(SiMe₃)- (C₅H₄N-2)]₂Ge₂ (112). When compound 66 was treated with one equivalent of potassium graphite, compound 112 was obtained as the major product. The reaction of 112 with azobenzene affords the 1,2-digermylene hydrazinide [PhNGe{N(SiMe₃) C(Ph)C(SiMe₃)(C₅H₄N-2)}]₂ (113). The Lewis base behaviour of 112 was studied. Treatment of 112 with one equivalent of diironnonacarbonyl gives a new unsymmetric germanium(I) dimer [{N(SiMe₃)C(Ph)C(SiMe₃)(C₅H₄N-2)(Fe(CO)₄)- Ge-Ge{N(SiMe₃)C(Ph)C(SiMe₃)(C₅H₄N-2)}] (114), while the reaction of 112 with two equivalent of diironnonacarbonyl leads to the formation of [{N(SiMe₃)C- (Ph)C(SiMe₃)(C₅H₄N-2)Fe(CO)₄)Ge]₂ (115). In addition, the reaction of 112 with sulfur affords the first germanium analogue of a dithiocarboxylic acid anhydride. / Chapter 3 deals with the synthesis of group 14 metal(II) complexes supported by iminophosphoranyl ligands. The synthesis of germanium(II) and tin(II) compounds derived from Ph₂P(2-CH₂Py)=NSiMe₃ (119) and H₂C(PPh₂=NSiMe₃)₂ (121) are described. Furthermore, the coordination chemistry of the hemilabile ligand Ph₂PCH₂(PPh₂=NSiMe₃) (131) was investigated. Iminophosphoranyl phosphine 131 undergoes metalation with Bu[superscript n]Li and Bu[superscript n]₂Mg to give the lithium complex [Li{CH(PPh₂)(PPh₂=NSiMe₃)}(THF)₂] (194) and the magnesium complex [Mg{CH- (PPh₂)(PPh₂=NSiMe₃)}₂] (193), respectively. 1,3-distannylcyclobutane 196 and 1,3-diplumbacyclobutane 200 were prepared from the reaction of 194 with the corresponding metal(II) chlorides. The reaction of 194 with GeCl₂(dioxane) leads to a tri-nuclear heterocyclic cage compound 195. In addition, the trapping reaction of 196 with diironnonacarbonyl affords the phoshpine-stabilized stannavinylidene 197. / Chapter 4 describes the conclusion of the first three chapters. / 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. / Chiu, Wang Kin. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in also in Chinese. / Tables of Contents --- p.vi / Acknowledgments --- p.i / Abstract --- p.ii / 摘要 --- p.iv / List of Compounds Synthesized --- p.xiv / Abbreviations --- p.xvi / Chapter Chapter 1 --- Reactivity of Pyridyl-1-azaallyl Germanium(II) Chloride / Chapter 1.1 --- Introduction --- p.1 / Chapter 1.1.1 --- Reactivity Study of Heteroleptic Organogermanium(II) Chlorides --- p.1 / Chapter 1.1.2 --- Synthesis and Structure of Pyridyl-1-azaallyl Germanium(II) Chloride --- p.13 / Chapter 1.1.3 --- Objectives --- p.15 / Chapter 1.2 --- Results and Discussion --- p.18 / Chapter 1.2.1.1 --- Synthesis of Metallo-germylenes from Pyridy1-1-azaallyl Germanium (II) chloride --- p.19 / Chapter 1.2.1.2 --- Spectroscopic Properties of [{N(SiMe₃)C(Ph)C(SiMe₃)- (C₅H₄N-2)}Ge-M(η⁵-C₅H₅)(CO)₃] (M = Mo (76), W (77) --- p.19 / Chapter 1.2.1.3 --- Molecular Structures of [{N(SiMe₃)C(Ph)C(SiMe₃) (C₅H₄N-2)}Ge-M(η⁵-C₅H₅)(CO)₃] (M = Mo (76), W (77)) --- p.20 / Chapter 1.2.2.1 --- Synthesis of Heteroleptic Germylene [{N(SiMe₃)C(Ph)C- (SiMe₃)(C₅H₄N-2)}Ge(η¹-C₅H₅)] (78) --- p.25 / Chapter 1.2.2.2 --- Spectroscopic Properties of [{N(SiMe₃)C(Ph)C(SiMe₃)- (C₅H₄N-2)}Geη¹-C₅H₅)] (78) --- p.25 / Chapter 1.2.2.3 --- Molecular Structures of [{N(SiMe₃)C(Ph)C(SiMe₃)- (C₅H₄N-2)}Ge(η¹-C₅H₅)] (78) --- p.26 / Chapter 1.2.3.1 --- Synthesis of Germanium(II)-Borane Adduct Adduct Adduct [{N(SiMe₃)C(Ph)C(SiMe₃)(C₅H₄N-2)}Ge(Cl)→(B(C₆H₅)₃)] (79) --- p.29 / Chapter 1.2.3.2 --- Spectroscopic Properties of Germanium(II)-Borane Adduct Adduct [{N(SiMe₃)C(Ph)C(SiMe₃)(C₅H₄N-2)}Ge(Cl)→(B(C₆H₅)₃)](79) --- p.29 / Chapter 1.2.3.3 --- Molecular Structures of Germanium(II)-Borane Adduct Adduct [{N(SiMe₃)C(Ph)C(SiMe₃)(C₅H₄N-2)}Ge(Cl)→(B(C₆H₅)₃)](79) --- p.30 / Chapter 1.2.4.1 --- Synthesis of Pyridyl-1-azaallyl Group 13 Metal Complexes from the Ligand Transfer Reaction between Pyridyl-1-azaallyl Germanium(II) Chloride and Group 13 Metal Halides --- p.34 / Chapter 1.2.4.2 --- Spectroscopic Properties of [{N(SiMe₃)C(Ph)C(SiMe₃)- (C₅H₄N-2)}GaCl₂] (80) and [{N(SiMe₃)C(Ph)C(SiMe₃)- (C₅H₄N-2)}₂InCl] (81) --- p.35 / Chapter 1.2.4.3 --- Molecular Structures of [{N(SiMe₃)C(Ph)C(SiMe₃)- (C₅H₄N-2)}GaCl₂] (80) and [{N(SiMe₃)C(Ph)C(SiMe₃)- (C₅H₄N-2)}₂InCl] (81) --- p.36 / Chapter 1.2.5.1 --- Hydrolysis of Pyridyl-1-azaallyl Germanium(II) Chloride with Water --- p.40 / Chapter 1.2.5.2 --- Spectroscopic Properties of [{HNC(Ph)CH(C₅H₄N-2)}GeCl] (82) --- p.40 / Chapter 1.2.5.3 --- Molecular Structure of [{HNC(Ph)CH(C₅H₄N-2)}GeCl] (82) --- p.41 / Chapter 1.3 --- Experimental for Chapter 1 --- p.43 / Chapter 1.4 --- References for Chapter 1 --- p.49 / Chapter Chapter 2 --- Synthesis and Reactivity Study of Pyridyl-1-azaallyl Germanium(I) Dimer / Chapter 2.1 --- Introduction --- p.55 / Chapter 2.1.1 --- General Aspects of Digermynes and Germanium(I) Dimers Supported by Bulky Ligands --- p.55 / Chapter 2.1.2 --- Objectives --- p.67 / Chapter 2.2 --- Results and Discussion --- p.69 / Chapter 2.2.1.1 --- Reduction of Pyridyl-1-azaallyl Germanium(II) Chloride:Synthesis of Germanium(I) Dimers [C(Ph)C(SiMe₃)- (C₅H₄N-2)]₂Ge₂ (111) and [N(SiMe₃)C(Ph)C(SiMe₃)- (C₅H₄N-2)]₂Ge₂ (112) --- p.69 / Chapter 2.2.1.2 --- Spectroscopic Properties of [N(SiMe₃)C(Ph)C(SiMe₃)- (C₅H₄N-2)Mg(μ-Cl)(THF)]₂ (110), [C(Ph)C(SiMe₃)- (C₅H₄N-2)]₂Ge₂ (111) and [N(SiMe₃)C(Ph)C(SiMe₃)- (C₅H₄N-2)]₂Ge₂ (112) --- p.71 / Chapter 2.2.1.3 --- Molecular Structures of [N(SiMe₃)C(Ph)C(SiMe₃)- (C₅H₄N-2)Mg(μ-Cl)(THF)]₂(110), [C(Ph)C(SiMe₃)- (C₅H₄N-2)]₂Ge₂ (111) and [N(SiMe₃)C(Ph)C(SiMe₃)- (C₅H₄N-2)]₂Ge₂ (112) --- p.72 / Chapter 2.2.2.1 --- Synthesis of [PhNGe{N(SiMe₃)C(Ph)C(SiMe₃)(C₅H₄N-2)}]₂ (113) --- p.80 / Chapter 2.2.2.2 --- Spectroscopic Properties of [PhNGe{N(SiMe₃)C(Ph)C(SiMe₃)(C₅H₄N-2)}]₂ (113) --- p.80 / Chapter 2.2.2.3 --- Molecular Structure of [PhNGe{N(SiMe₃)C(Ph)C(SiMe₃)(C₅H₄N-2)}]₂ (113) --- p.80 / Chapter 2.2.3.1 --- Synthesis of [{N(SiMe₃)C(Ph)C(SiMe₃)(C₅H₄N-2)(Fe(CO)4)- Ge-Ge{N(SiMe₃)C(Ph)C(SiMe₃)(C₅H₄N-2)}] (114) and [{N(SiMe₃)C(Ph)C(SiMe₃)(C₅H₄N-2)(Fe(CO)4)Ge]₂ (115) --- p.84 / Chapter 2.2.3.2 --- Spectroscopic Properties of [{N(SiMe₃)C(Ph)C(SiMe₃)(C₅H₄N-2)(Fe(CO)₄)- Ge-Ge{N(SiMe₃)C(Ph)C(SiMe₃)(C₅H₄N-2)}](114) and [{N(SiMe₃)C(Ph)C(SiMe₃)(C₅H₄N-2)(Fe(CO)₄)Ge]₂ (115) --- p.86 / Chapter 2.2.3.3 --- Molecular Structures of [{N(SiMe₃)C(Ph)C(SiMe₃)(C₅H₄N-2)(Fe(CO)₄)- Ge-Ge{N(SiMe₃)C(Ph)C(SiMe₃)(C₅H₄N-2)}](114) and [{N(SiMe₃)C(Ph)C(SiMe₃)(C₅H₄N-2)(Fe(CO)₄)Ge]₂ (115) --- p.87 / Chapter 2.2.4.1 --- Synthesis of the First Germanium Analogue of a Dithiocarboxylic Acid Anhydride: [Ge(S){N(SiMe₃)C(Ph)C(SiMe₃)(C₅H₄N-2)}]₂S (117) --- p.90 / Chapter 2.2.4.2 --- Spectroscopic Properties of [Ge(S){N(SiMe₃)C(Ph)C(SiMe₃)(C₅H₄N-2)}]₂S (117) --- p.91 / Chapter 2.2.4.3 --- Molecular Structure of [Ge(S){N(SiMe₃)C(Ph)C(SiMe₃)(C₅H₄N-2)}]₂S (117) --- p.92 / Chapter 2.3 --- Experimental for Chapter 2 --- p.95 / Chapter 2.4 --- References for Chapter 2 --- p.103 / Chapter Chapter 3 --- Synthesis and Characterization of Iminophosphoranyl Methanide Metal Complexes and Group 14 Metallavinylidenes / Chapter 3.1 --- Introduction --- p.109 / Chapter 3.1.1 --- A General Review of Phosphoranoimine Ligands --- p.109 / Chapter 3.1.2 --- A General Review of Group 14 Metal Complexes Containing Phosphoranoimine Ligands --- p.117 / Chapter 3.1.3 --- Objectives --- p.124 / Chapter 3.2 --- Results and Discussion --- p.126 / Chapter 3.2.1.1 --- Synthesis of Heteroleptic Chlorogermylene [{(C₅H₄N-2)C(SiMe₃)P(Ph)₂N(SiMe₃)}GeCl (189) and Chlorostannylene [{(C₅H₄N-2)C (SiMe₃)P(Ph)₂N(SiMe₃)}SnCl] (190) --- p.126 / Chapter 3.2.1.2 --- Spectroscopic Properties of [{(C₅H₄N-2)C(SiMe₃)P(Ph)₂N(SiMe₃)}GeCl (189) and Chlorostannylene [{(C₅H₄N-2)C (SiMe₃)P(Ph)₂N(SiMe₃)}SnCl] (190) --- p.127 / Chapter 3.2.1.3 --- Molecular Structures of [{(C₅H₄N-2)C(SiMe₃)P(Ph)₂N(SiMe₃)}GeCl (189) and Chlorostannylene [{(C₅H₄N-2)C (SiMe₃)P(Ph)₂N(SiMe₃)}SnCl] (190) --- p.128 / Chapter 3.2.2.1 --- Synthesis of Bis(iminophosphoranyl) Germanium(II) Compounds [{H₂C(PPh₂=NSiMe₃)₂}(GeCl₂)] (191) and [HC(PPh₂=N- SiMe₃)₂Ge(η¹-C₅H₅)] (192) --- p.132 / Chapter 3.2.2.2 --- Spectroscopic Properties of [{H₂C(PPh₂=NSiMe₃)₂}(GeCl₂)] (191) and [HC(PPh₂=NSiMe₃)₂Ge(η¹-C₅H₅)] (192) --- p.133 / Chapter 3.2.2.3 --- Molecular Structures of [{H₂C(PPh₂=NSiMe₃)₂}(GeCl₂)] (191) and [HC(PPh₂=NSiMe₃)₂Ge(η¹-C₅H₅)] (192) --- p.134 / Chapter 3.2.3.1 --- Synthesis of Magnesium and Lithium Methanide Complexes [Mg{CH(PPh₂)(PPh₂=NSiMe₃)}₂] (193) and [Li{CH(PPh₂)- (PPh₂=NSiMe₃)}(THF)₂] (194) --- p.139 / Chapter 3.2.3.2 --- Spectroscopic Properties of [Mg{CH(PPh₂)(PPh₂=NSiMe₃)}₂] (193) and [Li{CH(PPh₂)- (PPh₂=NSiMe₃)}(THF)₂] (194) --- p.140 / Chapter 3.2.3.3 --- Molecular Structures of [Mg{CH(PPh₂)(PPh₂=NSiMe₃)}₂] (193)and [Li{CH(PPh₂)- (PPh₂=NSiMe₃)}(THF)₂] (194) --- p.141 / Chapter 3.2.4.1 --- Synthesis of Phosphine-Stabilized Germavinylidene [{(PPh₂=NSiMe₃)(PPh₂)C=Ge:}{(PPh₂=NSiMe₃)(PPh₂)C}₂Ge→Ge:] (195) --- p.145 / Chapter 3.2.4.2 --- Spectroscopic Properties of [{(PPh₂=NSiMe₃)(PPh₂)C=Ge:}{(PPh₂=NSiMe₃)(PPh₂)C}₂Ge→Ge:] (195) --- p.146 / Chapter 3.2.4.3 --- Molecular Structure of [{(PPh₂=NSiMe₃)(PPh₂)C=Ge:}{(PPh₂=NSiMe₃)(PPh₂)C}₂Ge→Ge:] (195) --- p.146 / Chapter 3.2.5.1 --- Synthesis of Phosphine-Stabilized Stannavinylidene [{(PPh₂=NSiMe₃)(PPh₂)C=Sn:}{(PPh₂=NSiMe₃)(PPh₂)C=Sn→ Fe(CO)₄}] (197) --- p.151 / Chapter 3.2.5.2 --- Spectroscopic Properties of [Sn{{471}²-C(PPh₂=NSiMe₃)(PPh₂)}](196) and [{(PPh₂=NSiMe₃)(PPh₂)C=Sn:}{(PPh₂=NSiMe₃)(PPh₂)C=Sn→Fe(CO)₄}] (197) --- p.152 / Chapter 3.2.5.3 --- Molecular Structures of [Sn{{471}²-C(PPh₂=NSiMe₃)(PPh₂)}] (196) and [{(PPh₂=NSiMe₃)(PPh₂)C=Sn:}{(PPh₂=NSiMe₃)(PPh₂)C=Sn→Fe(CO)₄}] (197) --- p.157 / Chapter 3.2.6.1 --- Synthesis of 1, 3-diplumbacyclobutane [Pb{{471}²-C(PPh₂=NSiMe₃)- (PPh₂)}]₂ (200) derived from iminophosphoranyl phosphine --- p.163 / Chapter 3.2.6.2 --- Spectroscopic Properties of [Pb{{471}²-C(PPh₂=NSiMe₃)- (PPh₂)}]₂ (200) --- p.164 / Chapter 3.2.6.3 --- Molecular Structure of [Pb{{471}²-C(PPh₂=NSiMe₃)- (PPh₂)}]₂ (200) --- p.164 / Chapter 3.3 --- Experimental for Chapter 3 --- p.167 / Chapter 3.4 --- References for Chapter 3 --- p.176 / Chapter Chapter 4 --- Conclusion / Chapter 4.1 --- Conclusion --- p.186 / Chapter 4.1.1 --- Reactivity Study of Pyridyl-1-azaallyl Germanium(II) Chloride --- p.186 / Chapter 4.1.2 --- Synthesis and Reactivity Study of Pyridyl-1-azaallyl Germanium(I) Dimer --- p.187 / Chapter 4.1.3 --- Synthesis and Characterization of Iminophosphoranyl Methanide Metal Complexes and Group 14 Metallavinylidenes --- p.191 / Chapter 4.2 --- References for Chapter 4 --- p.193 / Chapter Appendix I / Chapter A. --- General Procedures --- p.194 / Chapter B. --- Physical and Analytical Measurements --- p.194 / Chapter Appendix II / Chapter Table A.1. --- Selected Crystallographic Data for Compounds 76-79 --- p.197 / Chapter Table A.2. --- Selected Crystallographic Data for Compounds 80-82 and 110 --- p.198 / Chapter Table A.3. --- Selected Crystallographic Data for Compounds 111-114 --- p.199 / Chapter Table A.4. --- Selected Crystallographic Data for Compounds 117 and 118-191 --- p.200 / Chapter Table A.5. --- Selected Crystallographic Data for Compounds 192-195 --- p.201 / Chapter Table A.6. --- Selected Crystallographic Data for Compounds 196-197 and 200 --- p.202

Chapter 1 describes the reactivities of bisgermavinylidene [(Me 3SiN=RPh2)2C=Ge→Ge=C(PPh2=NSiMe 3)2] (25). With the use of CpMnCO2(THF), Mn2(CO)10 and group 11 metal halides, manganese-germavinylidene complexes and germavinylidyl group 11 metal complexes were prepared respectively. Radical reaction of 25 with 2,2,6,6-tetramethylpiperidine N-oxide affords [(Me3SiN=RPh2)2C=Ge(ONCMe2C 3H6CMe2)2] (40). Cycloadditon reactions of 25 were studied. The reaction of 25 with benzil, azobenzene or 3,5-di-tert-butyl-o-benzoquinone affords [(Me3SiN=PPh2)2C=Ge{O(Ph)C=C(Ph)O}] (41), [(Me3SiN=PPh2)2C=Ge( o-C6H4NHNPh)](42) and [(Me 3SiN=PPh2)2C=Ge=C-(PPh2=NSiMe 3)2] (44), respectively. The C=Ge bond of 25 can undergo cycloaddition reactions with Me3SiN 3, Me3SiCHN2 or AdNCO (Ad = adamantly) to give [(Me3SiN=PPh2)2CGeN(SiMe3)N=N] (46), [(Me3SiN=PPh2)2C-GeN=NCH-SiMe 3] (48) and [(Me3SiN=PPh2)2 CGeN(Ad)C-O] (47), respectively. Furthermore, 1,2-addition products of rhodium(I) and tin(IV) complexes were prepared from the reaction of 25 with (cod)RhCl and (nBu) 3SnN3, respectively. The syntheses of bimetallic chlorides [(Me3SiN=PPh2)2(GcCl)CMn(mu-Cl)]2 (51) and [(Me3SiN=PPh2)2(GeCl)CFeCl] (52) are also reported. / Chapter 2 concerns the reactivities of bis(iminophosphorano)methanide tin(II) chloride [HC(PPh2=NSiMe3)2SnCl] ( 79). The reactivity of the lone pair in 79 was studied. The reaction of 79 with benzil or 3,5-di-tert-butyl- o-benzoquinone gives the corresponding cycloaddition products. Treatment of 79 with NaN3 or AgOSO2CF3 affords the corresponding substituted heteroleptic stannylenes. The reaction of 79 with W(CO)5THF gives an adduct [HC(PPh 2=NSiMe3)2(Cl)Sn→W(CO)5] ( 81). Compound 79 reacts with Fe{N(SiMe3) 2}2 to afford [HC(PPh2=NSiMe3) 2Fe(mu-Cl)]2 (86). Moreover, treatment of 79 with LiC≡CPh gives [HC(PPh2=NSiMe3) 2C(Sn)=C(Ph)Sn(C≡CPh)2]2 (87). / Chapter 3 deals with the preparation and characterization of group 14 bis(thiophosphinoyl) metal complexes. The newly developed ligand [(S=PPr i2CH2)2-C5H 3N-2,6] (126) undergoes metalation with nBuLi or (nBu)2Mg to afford the lithium complex [Li{(S=PPri 2CH)(S=PPi2CH2)C 5H3N-2,6}(Et2O)] (127) and magnesium complex [Mg(S=PPri2CH)2C 5H3N-2,6] (128), respectively. 1,3-Distannylcyclobutane and 1,3-diplumbacyclobutane were prepared from treatment of 126 with M{N(SiMe3)2}2 (M Sn, Pb) by the amine-elimination reaction. Furthermore, compound 127 reacts with GeCl2.dioxane or SnCl2 to afford digermylgermylene Ge[GeCl2{(S=PPr i2CH)(S=PPri 2CH2)C5H3N-2,6}]2 ( 131) and ionic tin(II) complex [{C5H3N-2,6-(CH 2PPri2=S)(CHPPr i2=S)}SN+][SnCl3 -] (134), respectively. / Chapter 4 describes the conclusion of the first three chapters. The future works of the first three chapters were also reported. / This thesis is focused on four areas: (i) the reactivities of bisgermavinylidene; (ii) the reactivities of bis(iminophosphorano)methanide tin(II) chloride; (iii) the synthesis of group 14 bis(thiophosphinoyl) metal complexes and (iv) conclusions and future works. / Kan, Kwok Wai. / "Aug 2007." / Adviser: Kevin W. P. Leung. / Source: Dissertation Abstracts International, Volume: 69-02, Section: B, page: 1007. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references. / 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. / Abstract in English and Chinese. / School code: 1307.

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Phosphine complexes of nickel and palladium provide the best catalysts for the homogeneous catalysed carbon-carbon bond forming reaction between an organometallic nucleophile and an organic electrophile. Use of a homochiral ligand on the catalyst can lead to stereoselectivity in the cross-coupling reaction, with high ee's of coupled product being obtained. The processes of selectivity in the transmetalation step of the catalytic cycle have not been elucidated and the initial aim of the project was to study these processes. Initial experiments using organotin derivatives as the organometallic nucleophile highlighted the problems of selectivity and the forcing conditions needed in the attempted transfer of a benzyl group from the tin to the palladium catalyst. The compounds [8- (dimethylamino)-1-naphthyl]methyldiphenyltin (60) and [2-((dimethylamino)methyl) phenyl]methyldiphenyltin (70) were prepared and their reactivity in the palladium catalysed cross-coupling with 2-furoyl chloride, to give 2-benzoylfuran, was investigated. These molecules were found to undergo facilitated transfer of a phenyl group compared to transfer from control molecules. The effect was tested and attributed to the internal nucleophilic attack at the tin atom by the lone pair on the nitrogen atom. The compound [2- ((dimethylamino)methyl)-3-trimethylsilylphenyl]methyldiphenyltin (79) was prepared to test the effects of steric buttressing within the molecule, but was found to be of the same order of magnitude of reactivity as (60) and (70). All three molecules showed a reactivity of at least an order of magnitude greater than control compounds. The effect did not prove applicable to the transfer of a benzyl group or in other coupling reactions. The effect of palladium ligation was tested and the ligand triphenyl arsine found to increase the rate of the coupling reaction. The two facilitating processes were found to work in a co-operative fashion, giving a rate enhancement of ca. one hundredfold over control reactions. The nickel catalysed cross-coupling of α-substituted sp³ hybridised Grignard reagents with allylic esters was attempted, but proved unsuccessful. Stoichiometric reactions with nickel complexes were also found to be unsatisfactory in yielding coupled products. The synthesis of α-substituted diorganozinc reagents was attempted, but furnished only homocoupled products. The reaction of dibenzylzinc with aldehydes was found to proceed in the absence of catalyst, highlighting the reactivity of a benzylzinc moiety.

The iridium(III) methyl diarylphosphide complexes, Ir(CH₃PR₂-[N(SiMe₂CH₂PPh₂)₂] (2a: R = phenyl, 2b: R = meta-tolyl) had been prepared previous to this work. The iridium(III) dimethylphosphide complex, Ir(CH₃)PMe₂-[N(SiMe₂CH₂PPh₂)₂], 2c, is readily prepared in situ by transmetallation of the Ir(CH₃)I[N(SiMe₂CH₂PPh₂)₂] with KPMe₂ at -30°C. The synthesis of the phenylphosphide complex Ir(CH₃)PHPh[N(SiMe₂CH₂PPh₂)₂], 2d, involves deprotonation of the six-coordinate iridium(III) phenylphosphine complex, Ir(CH₃)I-(PH₂Ph)[N(SiMe₂CH₂PPh₂)₂], with KO¹Bu. Thermolysis of 2a and 2b yields the six-coordinate iridium(III) cyclometallated hydride complexes fac-Ir(ɳ²-CH₂PR₂)H[N(SiMe₂CH₂PPh₂)₂], 3a and 3b. The dimethylphosphide complex 2c undergoes the same rearrangement to afford 3c but more rapidly. Thermolysis of 3a-3c yields the square planar iridium(I) phosphine complexes of the formula, Ir(PCH₃R₂)[N(SiMe₂CH₂PPh₂)₂], 4a-4c. Some of the intermediates proposed in the thermolysis of 2a are synthesised independently by the reaction of iridium methylidene complex, Ir=CH₂[N(SiMe₂CH₂PPh₂)₂]. 10, with PHPh₂. The complex fac-Ir(ɳ²-CHPhPMe₂)H[N(SiMe₂CH₂PPh₂)₂] is generated from the reaction of Ir(CH₂Ph)Br[N(SiMe₂CH₂PPh₂)₂] with KPMe₂ without intermediacy of the corresponding phosphide complex. The photolysis of 2a-2c also yields species 4a-4c; however, no intermediacy of the cyclometallated hydride complexes 3a-3c is observed during this transformation. Upon thermolysis of the phenylphosphide complex 2d, only the corresponding iridium(I) phosphine complex, Ir(PHCH3Ph)[N(SiMe2CH2PPh2)2], 4d, is obtained, which is also the photolysis product of 2d. Ir(CH₃)PPh₂[N(SiMe₂CH₂PPh₂)₂], 2a, reacts at -78°C with dimethyl-acetylenedicarboxylate to yield an octahedral iridium(III) complex in which the alkyne has bridged between the phosphide ligand and the phosphine group of the chelating ligand. In addition, one of the phenyl groups from the chelating phosphine has migrated to the metal. On the other hand, Ir(CH₃)PMe₂[N(SiMe₂CH₂PPh₂)₂], 2c, reacts with the same alkyne to yield a product in which the alkyne has bridged between the phosphide group and the iridium centre. The reaction of 2a with diphenylacetylene affords Ir(PhC≡CPh)[N(SiMe₂CH₂PPh₂)₂] and free methyl-diphenylphosphine. Complex 2a reacts with terminal alkynes (RC≡CH; R = H, Ph, ¹Bu) to yield acetylide complexes of formula Ir(CH₃)PHPh₂(C≡CR)[N(SiMe₂CH₂PPh₂)₂]- The methylidene complex, lr=CH₂[N(SiMe₂CH₂PPh₂)₂], 10, prepared by the reaction of Ir(CH₃)I[N(SiMe₂CH₂PPh₂)₂] with KO¹Bu, reacts with phosphines PHR₂ (R = Ph, ¹Bu) to afford the cyclometallated hydride complexes, fac-Ir(ɳ²-CH₂PR₂)H[N(SiMe₂CH₂PPh₂)₂], via a five-coordinate methylidene phosphine intermediate. The reaction of 10 with PH₂Ph yields similar cyclometallated hydride product, but in this case the five-coordinate intermediate is not observed. The methylidene complex 10 reacts with the electrophiles MeI and AlMe₃ to yield Ir(ɳ²-C₂H₄)H(I)[N(SiMe₂CH₂PPh₂)₂] and Ir((µ-AlMe₂)H[N(SiMe₂CH₂PPh₂)₂], respectively. Reaction of 10 with HC≡CH affords an ɳ³˗allyl acetylide complex Ir(ɳ³-C₃H₅)(C≡CH)[N(SiMe₂CH₂PPh₂)₂]. A trimethylenemethane complex, fac-Ir{ɳ⁴-C(CH⁴₂)₃}[N(SiMe₂CH₂PPh₂)₂], is obtained readily upon exposing 10 to 1,2-propadiene. The reaction of 10 with 1,3-butadiene affords a pentenyl product, Ir(σ-ɳ³-C₅H₈)[N(SiMe₂CH₂PPh₂)₂]. In previous studies, the iridium(I) ɳ²-cyclooctene species, Ir(ɳ²-C₈H₁₄)-[N(SiMe₂CH₂PPh₂)₂], 25, has served as a useful starting material in the preparation of a number of iridium(I) and iridium(III) amide complexes. This complex is thermally stable, but upon photolysis, it yields Ir(H)₂[N(SiMe₂CH₂PPh₂)₂] and a mixture (2:1) of free 1,3-and 1,5-cyclooctadiene. This dehydrogenation process proceeds through ɳ³-allyl hydride intermediate, Ir(ɳ³-C₈H₁₃)H[N(SiMe₂CH₂PPh₂)₂]- The cyclo-octene ligand in 25 can be replaced by 1,3-butadiene and. 1,2-propadiene. The products obtained from these reactions are Ir(ɳ⁴-C₄H₆)[N(SiMe₂CH₂PPh₂)₂] and Ir(ɳ²-C₃H₄)[N(SiMe₂CH₂PPh₂)₂]. respectively. The reaction of 25 with AlMe₃ affords Ir(µ-AlMe₂)Me[N(SiMe₂CH₂PPh₂)₂]. / Science, Faculty of / Chemistry, Department of / Graduate

Ph.D. / In order for any new useful complexes to be developed, whether of catalytic, biological or of other importance, it is very important that sufficient knowledge exists regarding the fundamental principles applying to the chemistry involved. In all chemical processes involving metal complexes, the coordinated ligands govern the reactions to a great extent. It is thus very important that the properties (solubility, reactivity, steric bulk, etc.) of various ligands of these complexes is clearly understood in order to enable intelligent adjustments to be made, inducing the effects of choice. In most catalytic cycles, basic chemical reactions like substitution, addition, oxidative addition and reductive elimination are of importance. Some of the methods used to quantify ligand properties include single crystal X-ray studies as well as investigating various reactions on model square planar complexes. Several problems are normally associated with this type of investigation and are summarized below along with the aims of this study to improve upon this. (i) Very often the Vaska type compounds crystallise on an inversion centre as is shown in a generalized structure in Figure 1.1. This creates several problems ranging from less accurate bond distances/angles to problematic refinement of single crystal data. As the disorder is ruled by symmetry, the occupancies of the disordered atoms are 50%. The example shown in Figure 1.1 is also a fortunate case where the disordered atoms do not have the same positions, making refinement of the data easier, but there are examples27 such as [Pt(Me)Cl(PCy3)2] where the disordered moieties (Me- and Cl-) occupy virtually the same positions. In examples such as these restraints have to be applied, i.e. fixing bond distances to average distances from literature. The important parameter of the ligand trans effect is then meaningless and cannot be reliably compared to data from solution studies. / Prof. A. Roodt