One particular aspect of the chemistry of the trifluoromethyl group is its high electron-withdrawing power which reduces the donor properties of normally strong bases. This investigation has been concerned with the chemistry of some phosphines containing this group. For this purpose, substituted phosphines containing methyl or phenyl and trifluoromethyl groups have been prepared. For the study of their donor properties, a series of addition compounds with boron trifluoride, platinum(Il) chloride and nickel(II) salts have been prepared. The reported methods for preparing the methyl-trifluoromethyl-phosphines do not produce a good yield; therefore, an attempt has been made towards a better understanding of the reactions. The phenyl-trifluoromethyl-phosphines have been prepared by reacting trifluoroiodo-methane with a phosphorus compound containing a P-P bond. Thus, a reaction with tetraphenylcyclotetraphosphine gives phenylbistrifluoromethylphosphine and phenyltrifluoromethyl-iodophosphine, and reaction with tetraphenyldiphosphine gives diphenyltrifluoromethylphosphine. The latter has also been prepared by reaction of trifluoroiodomethane with either triphenylphosphine or diphenylchlorophosphine. These new phosphines are colorless liquids (except phenyltrifluoromethyliodophosphine which is reddish-brown) of high boiling point. They are stable in air and cannot be hydrolysed with acid or water, except the iodophosphine C₆H₅CF₃PI, which reacts with water to give phenyltrifluoromethylphosphinic acid, a new oxyacid. Phenylbis-trifluoromethylphosphine can be hydrolysed with aqueous alkali to give fluoroform and phenylphosphonous acid. Diphenyltrifluoromethylphosphine, on the other hand, cannot be hydrolysed by aqueous alkali, but reacts slowly with alcoholic potassium hydroxide to give fluoroform and diphenylphosphinic acid. The phosphines form a further series of new compounds by reaction with halogens. Phenylbistrifluoromethylphosphine reacts with iodine to form trifluoroiodomethane, but forms phenylbistrifluoromethyldibromophosphorane with bromine. This compound also gives phenyltrifluoromethylphosphinic acid on aqueous hydrolysis, as obtained in the case of phenyltrifluoromethyliodophosphine. Besides forming the dibromophosphorane, diphenyltrifluoromethylphosphine is the first trifluoromethyl-phosphine known to form a diiodophosphorane. It is interesting to note that diphenyltrifluoromethylphosphine is difficult to hydrolyse, whereas the phosphoranes can be hydrolysed easily, giving fluoroform and diphenylphosphinic acid. By reaction with methyl iodide, this phosphine also forms a new phosphonium compound, methyldiphenyltrifluoromethylphosphonium iodide, which is readily hydrolysed by cold water with the loss of the trifluoromethyl group. In general, phosphines containing one trifluoromethyl group show similar properties to those of their parent compounds, trimethylphosphine and triphenylphosphine, while those containing two trifluoromethyl groups are very similar in their behaviour to tristrifluoromethylphosphine. The phosphines containing more than one CF₃ group do not form addition compounds with boron trifluoride. The phenyl-trifluoromethyl-phosphines form more stable complexes than the methyl-trifluoromethyl-phosphines. The phosphines containing up to two trifluoromethyl groups form complexes with platinum(II) chloride. A complex with tristrifluoromethylphosphine could not be obtained. Except dimethyltrifluoromethylphosphine, which forms mainly a cis isomer, the other phosphines, CH₃(CF₃)₂P,C₆H₅(CF₃)₂P, and (C₆H₅)₂ CF₃P form mainly trans isomers. The non-occurrence of the tristrifluoromethylphosphine complex and the production of mainly trans isomers of the above-mentioned phosphines has been interpreted in terms of steric phenomenon. The phosphines containing more than one CF₃ group do not form complexes with nickel(II) salts. The nitrato complexes of trimethylphosphine and dimethyltrifluoromethyl-phosphine are paramagnetic, while the dichloro, dibromo, diiodo, and dithiocyanato complexes are diamagnetic. A correlation of the various properties, for example boiling points and heats of vaporization, has shown that the trifluoromethyl substituted phosphines are not anomalous in the general family of phosphines. An attempt has also been made towards a study of the infra-red spectra of the phosphines and their compounds, and towards a correlation with the spectra of other phosphorus compounds. Finally, an approximate estimate of the "electronegativities" of a wide range of substituted phosphines gives values which are in good agreement with the observed order of reactivities of the phosphines studied, and assists in correctly placing the trifluoromethyl-phosphines in such a range of compounds. ` / Science, Faculty of / Chemistry, Department of / Graduate

Current knowledge of mechanistic organometallic chemistry has resulted largely from the study of mononuclear transition metal complexes. The possibility that different primary organometallic processes involving two or more metal centres may exist has been addressed only recendy. Reactivity studies on a simple, well defined binuclear system ought to provide fundamental insights into the nature of such polynuclear primary processes. The binuclear rhodium hydrides {[R₂P(CH₂)nPR₂]Rh(μ-H)}₂ (R = Pri, n = 2-4, 1a-1c; R = OPri, n = 2, 1d) were thus reacted with a variety of organic compounds in an attempt to define primary processes involving two metal centres. The reactions of 1a-c with dihydrogen proceed rapidly to produce fluxional binuclear tetrahydrides whose structure is dependent on the chelate ring size of the diphosphine ligand. The dihydrides also catalyze the hydrogenation of olefins. Two mechanistic pathways for this cycle are proposed to exist as supported by chemical and kinetic evidence. One utilizes binuclear intermediates, the other mononuclear; the latter predominates in the 1b catalyzed system (chelate ring size of six) while the former is favoured in the cycle mediated by la (chelate ring size of five). The reactions of 1a and 1b with 1,3-dienes led to the solid (X-ray diffraction) and solution state characterization of binuclear complexes incorporating bridging dienyl ligands in the previously unobserved μ-ƞ⁴-ϭ and μ-ƞ³-ƞ³ "partial sandwich" bonding modes. A fluxional process interconverting the two bonding modes was observed spectroscopically in the products of the 1a/butadiene reaction and a model accounting for this is proposed. Labelling and alternate synthetic studies, as well as the observation of an intermediate at low temperature, support a mechanism for these reactions which involves the dehydrogenation of the dihydrides followed by further reaction of [(P₂)Rh]₂ with a second equivalent of diene. Bridging amido hydrides of general formula [(P₂)Rh]₂(μ-NR'CH₂R")(μ-H) are produced in the reactions of 1a and 1d with imines (R'N=CHR"). Mechanistic studies reveal that initial ϭ-donation of the imine lone pair; of electrons to one Rh followed by π-coordination of the C=N bond to the other precedes formal insertion of the C=N bond into Rh-H. This proposal is consistent with the results of labelling and kinetic studies, but the crux of its support lies in the spectroscopic observation of two intermediates en route to the product amido hydrides. The specific synthesis of cationic μ-ƞ²-ϭ imine complexes closely related to one of the proposed intermediates in the reaction was carried out to confirm the plausibility of such an intermediate. Reaction of the amido hydrides with dihydrogen was slow in producing free amine and the hydrogen adducts of 1a or 1d, precluding the use of these dihydrides as catalyst precursors in the homogeneous hydrogenation of imines. Reaction of 1a and 1d with nitriles (R"'C=N) produces μ-alkylideneimido hydride complexes of general formula [(P₂)Rh]₂(μ-N=CHR'")(μ-H). One derivative (P₂, R = Pri, n = 2; R"' = CH₃) has been characterized by X-ray crystallography. Further reaction of these complexes with dihydrogen yield the amido hydrides [(P₂)Rh]₂(μ-NHCH₂R"')(μ-H). No intermediates in these reactions were observed, precluding meaningful mechanistic proposals for this stepwise reduction of nitriles as mediated by two metal centres. / Science, Faculty of / Chemistry, Department of / Graduate

The principal organometallic products resulting from the reactions of Na[(ƞ⁵-C₅H₄R)Cr(CO)₃] (R = H or Me) with allyl chlorides in THF are the green, dimeric [(ƞ⁵-C₅H₄R)Cr(CO)₃]₂ complexes (51-67% yields). The red organometallic by-products usually formed during these conversions are novel (ƞ⁶-6-alkenylfulvene)Cr(C0)₃ complexes (5-8% yields) which have been characterized completely by conventional spectroscopic methods. Dark green [W(N0)₂Cl₂]n may be synthesized in high yields by two preparative methods. The first method involves treatment of WCl₆ in CH₂Cl₂ with an excess of NO, and it proceeds via the isolable intermediate complexes, dark violet c̲i̲̲s̲-W(N0)₂Cl₄ and bright green f̲a̲c̲-W(NO)₃Cl₃. The second method involves controlled reaction of W(CO)₆ with two equivalents of ClN0 in CH₂Cl₂. It is initiated by traces of oxidant and probably proceeds via a catalytic, radical-chain mechanism that is described. If either reaction is effected in the presence of two equivalents of CH₃CN, then yellow-green W(N0)Cl₃(CH₃CN)₂ is the only nitrosyl-containing product formed. Polymeric [W(N0)₂Cl₂]n may be cleaved by a variety of Lewis bases, L, and (n̲-Bu)₃Sn(C₅H₅) to form W(N0)₂Cl₂L₂ (L = phosphine, phosphite, CH₃CN, etc.) and CpW(N0)₂Cl (Cp - ƞ⁵-C₅H₅), respectively, in good yields. The synthesis of the electron-rich nitrosyl complexes CpM(NO)L₂ (M = Cr, Mo, or W; L = P(0Me)₃, PMePh₂, P(n̲-Bu)₃, SbPh₃ or 1/2 (dppe)) is described. They are preparable in moderate to high yields by the reduction of the iodo dimers [CpM(NO)In]₂ (M = Cr, n = 1; M = Mo or W, n = 2) with sodium amalgam in THF ln the presence of the appropriate Lewis base, L, and they exhibit metal-dependent trends in vNO (Cr » Mo > W), δ ³¹P (Cr > Mo » W), and ²J₃₁p (Cr < Mo < W). These reduction reactions proceed via a number of transient intermediates, some of which are isolable. A unified mechanism for these reductive syntheses is proposed. The novel complexes, CpMo(NO)(ƞ⁴-trans-diene) (diene = acyclic conjugated diene) and CpMo(NO)(ƞ⁴-c̲i̲s̲-2,3-dlmethyl-butadiene)t are preparable in moderate yields by the reduction of [CpMo(NO)I₂]₂ with sodium amalgam in THF in the presence of the appropriate diene. The reaction between [CpMo(NO)I₂]₂ and C₄H₆•Mg•2(THF) results in the formation of a green, isolable oligomeric complex CpMo(NO)I(ƞ³-C₃H₄R) (where R = CH₂MgI and the nitrosyl oxygen acts as a Lewis base towards Mg) that can be hydrolyzed to CpMo(NO)I(ƞ³-C₄H₇) or converted to CpMo(NO)(ƞ⁴+-t̲r̲a̲n̲s̲-C₄H₆). These diene complexes have been fully characterized by conventional spectroscopic techniques (extensive ¹H and ¹³C NMR spectra being particularly informative) and by single-crystal X-ray structural determinations of CpMo(NO)(ƞ⁴-t̲r̲a̲n̲s̲-2,5-dimethyl-2,4-hexadiene) and CpMo(N0)(ƞ⁴-c̲i̲s̲-2,3-dimethyl-butadlene). A molecular orbital rationale for the structural and spectrocopic properties and relative stabilities of these c̲i̲s̲- and t̲r̲a̲n̲s̲-diene complexes is then presented. / Science, Faculty of / Chemistry, Department of / Graduate

Values of thermodynamic equilibrium constants were obtained by potentiometric measurements with a Beckman Model GS pH meter in aqueous solutions for the following reactions: 1. The step-wise dissociation or protons from CH_3CHNH_3COOH^+ and C_6H_5CH_2CHNH_3COOH^+ at 0, 10, 20, 30, and 40°C. 2. The step-wise formation of bis-alamino copper(II) and bis-phenylalanino copper(II) at o, 10, 20, 30, and 40°C. 3. The step-wise formation of tris-acetylacetonato iron(III) at 30°C. Enthalpy and entropy changes were calculated for the reactions in 1 and 2, above, from the temperature dependence of the equilibrium constants. Measurements were made and data obtained for the reactions in 3 at several different ionic strengths, metal ion concentrations, and pH values. It was found that the addition of a phenyl group to alanine lowers the pK of dissociation of both protons from the acid species of the amino acid. This is attributed to the attraction which the phenyl group has for electrons. The same effect caused the log K of the first step-wise chelate of copper(II) to be lower with phenylalanine than with alanine. The second step-wise chelate of copper(II) with phenylalanine, however, has a higher log K value than the equivalent alanine chelate. This shows that the phenyl group influences the electronegativity of the copper(II) ion in the first chelate. The calculated formation constants of tris-acetylacetonato iron(III) were independent of metal ion concentration and ionic strength but increased as the pH of the measurements decreased. This was attributed to hydrolysis of the iron(III) ion. It was shown that at least qualitative measurements of equilibrium constants maybe made at pH values as low as 1.5 with a Beckman Model GS pH meter. There was no measurable increase in the proton concentration when Fe^+++ was added to solutions containing glycine or alanine. It was concluded from this that chelation does not occur to any great extent between Fe^+++ and these amino acids, although it has recently been reported in the literature that strong chelates are formed between Fe^+++ and simple amino acids. It is possible that complexes, but not chelates, are formed in the reactions of F^+++ with simple amino acids. The reaction of dilute perchloric acid with certain metal ions produces a small amount of Cl^-, indicating that an oxidation-reduction reaction occurs between the perchlorate ion and the metal ion. It was previously thought that dilute perchloric acid is not an oxidizing agent. Most of the calculations necessary in processing the data obtained were programmed for the IBM 650 computer.

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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