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Thesis (MSc)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: This study comprises the preparation and characterization of various novel organometallic complexes of palladium(ll) which contain symmetric and unsymmetric (heteroatom-containing) r..-dicarbonyl-type ligands, T]3-heteroallyl ligands and T]3-coordinated trimethylsilyl-containing ligands. With the ultimate objective of preparing potential catalytic precursors similar to known catalytic precursors which exhibit hemilabile activity, the main goals of this study were the following: - • Investigate the coordination mode of the aforementioned ligand-types to the palladium of the starting compound, trans-[Pd(CeHs)CI{P(CeHshhl (1), by physical measurements. • Carry out single crystal structure determinations where possible. • Investigate the influence of the properties of the ligands on the stability of the prepared complexes. • Investigate the existence of hemilability (if any) in the prepared complex. The deprotonated symmetric and unsymmetric f!,-dicarbonyl-type ligands readily bind to the palladium of the starting compound in a bidentate fashion through the oxygens by displacing a triphenylphosphine group and producing easily removable sodium chloride. These complexes show that a negative charge can be accommodated in a delocalized fashion by the -S=O and - P=O groups of these acac--type ligands in a similar manner to the carbonyl groups of acetylacetonate. However, no evidence of hemilabile activity was found in this series of complexes. In a similar fashion, the deprotonated T]3-heteroallyl ligands, L = [PhzPS£], [PhCOz-], [PhC{NSi(CH3hhl [(Ph)zP{NSi(CH3hh-], were linked to palladium in the same starting complex, in T]3-fashion by triphenylphosphine substitution. No evidence of hemilabilty was evident in this series of complexes, but when L = [PhzPSz-], an exchange of the coordinated triphenylphosphine group with the free triphenylphosphine group was observed in the reaction mixture. Finally, the preparation, isolation and spectroscopic characterization of several T\3-allyl paliadium(lI) complexes with ligands of the type R-TeCH2CH2CQQCH3, (R = isopropyl, t-butyl ,ethyl) were attempted with the compound bis-( T\3-allyl )-di-~ -iodo-dipalladium( II), [T\3 -( CH2CHCH2J2Pd212J, which had also now been crystallographically characterized. Chelate formation by TeAQ coordination seemed possible by halide precipitation with silver tetrafluoroborate. Unfortunately the resulting compounds were too unstable to be isolated in the pure form for characterization. / AFRIKAANSE OPSOMMING: Die studie behels die bereiding en karakterisering van verskeie nuwe palladium(lI) organometaalkomplekse met inbegrip van simmetriese en onsimmetriese (heteroatoom bevattende) ~-dikarboniel-tipe ligande, 113- heteroallielligande en 113_gekoordineerdetrimetielsiliel bevattende ligande. Met die beoogde einddoel die bereiding van potensiele katalitiese voorgangers soortgelyk aan bekende katalitiese voorgangers met hemilabiele aktiviteit, sluit die hoof mikpunte van die studie die volgende in: - • 'n Ondersoek na koordinasie-wyse van die bogenoemde ligand tipes aan die palladium van die uitgangstof, trans-[Pd(C6Hs)CI{P(C6Hshhl (1), met behulp van fisiese bepalings. • Enkel kristal struktuur bepalings waar moontlike. • 'n Ondersoek na die invloed van die einskappe van die ligande op die stabilitiet van die komplekse. • 'n Ondersoek na die bestaan van hemilabiele aktiwiteit (indien enige) in die voorbereide complekse. Die gedeprotoneerde simmetriese en onsimmetriese ~-dikarboniel-tipe ligande het geredelik, bidentaat deur middel van die suurstowwe gebind aan die palladium van die uitgangstof deur die verplasing van die trifenielfosfien group en die vorming van verweiderbare natriumchloried. Hierdie komplekse dui aan dat 'n negatiewe lading wei geakkommodeer kan word deur delokalisasie by die -S=O- en -P=O-groepe van hierdie acac"-tipe Iigande, soortgelyk aan die karbonielgroep van asetielasetonaat. Geen hemilabiliteit is waargeneem in hierdie reeks komplekse nie. Die gedeprotoneerde 113-heteroalliel Iigande, L = [Ph2PS£), [PhCO£), [PhC{NSi(CH3h}£), [(PhhP{NSi(CH3hhl is op 'n soortgelyke wyse 113- gekoppel aan palladium van dieselfde uitgangstof met trifenielfosfien verplasing. Geen hemilabiliteit is waargeneem in hierdie reeks komplekse nie, maar wanneer L = [Ph2PS£], is 'n uitruiling van 'n gekoordineerde trifenielfosfien met 'n vrye trifenielfosfien in die reaksiemengsel waargeneem. Die bereiding, isolasie en spektroskopiese karakterisering van Tj3-alliel paliadium(lI) komplekse met ligande van die tipe R-TeCH2CH2COOCH3, (R = isopropiel, t-butiel ,etiel) is gepoog met die uitgangstof bis-(Tj3-alliel)-di-ll-iododipaliadium( II), [Tj3-(CH2CHCH2hPd2b], wat volledig gekarakteriseer was. Chelaat-vorming deur TeAO-koordinasie het moonlik blyk te wees deur halied presipitasie met behulp van AgBF4. Die komplekse is baie onstabiel en is dit gevolglik nie moontlik am die komplekse suiwer te isoleer en te karakteriseer nie.

The successful application of Tppts, and its derivatives, in biphasic transition metal-catalysed reactions opened up a new field of chemistry requiring a rational design of water-soluble ligands. The main objective of the research described in this dissertation was the preparation and the application of new water-soluble phosphine ligands. The ligands were prepared by the use of carbon nucleophiles and chlorophenylphosphine derivatives. The carbon nucleophiles included malonate derivates, which were subsequently reduced to the di-alcohols and were transformed into water-soluble phosphines by the reaction with 1,4-butanesultone. Secondary and tertiary malonate nucleophiles were used and the steric demands of compounds containing more than one malonate group were investigated. Various attempts to obtain water-soluble compounds from dimalonate phosphine oxides failed. TBDMS-protected aryl halides were also used as nucleophiles. One (or two) of these silyl ethers was reacted with chlorophenylphosphine derivatives and after deprotection with TBAF the compounds were made water-soluble by a reaction with 1,4-butanesultone. The hydrogenation of arylphosphine oxides to form cyclohexylphosphine oxide derivatives was also investigated. However, these cyclohexylphosphines were more easily obtained by the reaction between the previously mentioned carbon nucleophiles and chlorocyclohexylphosphine derivatives, which were freshly prepared. A series of cyclohexyl-containing water-soluble phosphines was prepared in this way. The oxygen sensitive nature of phosphines lead to two different approaches in the reaction route: the phosphines were either borane protected followed by a subsequent deprotection step, or the phosphines were allowed to oxidise and were reduced back to the free phosphine at a later stage. The efficiency of both approaches in the reaction routes was examined. The deprotection of phosphine-boranes was performed using various “new” deprotecting reagents and the borane-species and free phosphines were separated using water/organic extractions. The various extraction coefficients of the amine-borane complexes were determined. The newly prepared ligands were used in a variety of palladium-catalysed reactions as well as in the hydroformylation of 1-octene employing rhodium. The reactions were performed in both neat organic solvents as well as mixtures between water and DMF or toluene and the results were compared to the use of Tpp and Tppts. It was found that many of the new ligands afforded superior yields compared to those of Tpp and Tppts. In the last part of the study, various diphenylphosphinic amides were used as DoM-groups. Sec- and tert-BuLi were used together with a variety of electrophiles to facilitate ortho-substitution on either one or two rings on the amides. This was seen as a start of a new approach towards functionalised phosphine ligands. / Prof. D.B.G. Williams

The focus of this thesis is the synthesis of organometallic complexes incorporating the η8-permethylpentalene titanium moiety (η⁸-Pn*Ti), their characterisation, and their reactivity with small molecules. <b>Chapter One</b> summarises the chemistry of the pentalene molecule, from its instability in the free state to the incorporation of the hydrocarbon into organometallic complexes. The chapter continues with a review of the coordination modes available to Pn and concludes with a brief discussion on the effects of permethylation of hydrocarbon ligands and the advent of permethylpentalene (Pn*). <b>Chapter Two</b> documents the improved synthesis of [Pn*TiCl(μ-Cl)]₂ utilising isomeric control imparted on the Pn* synthon, Pn*(SnMe₃)₂. This protocol permits access to a variety of methylated compounds through metathesis chemistry, of which five have been crystallographically elucidated, revealing the fold angle to be reliant on an interplay between steric and electronic factors. Mono-, bi- and trimetallic {Pn*TiMe₂, [Pn*TiMe(μ-Cl)]₂ and [Pn*Ti(μ-Me)]₂(μ-CH₂), and [Pn*TiMe(μ-Me)₂]₂Mg respectively} species were synthesised dependent on the methylating agent employed and they displayed varying thermal stabilities, with the dimeric nature of [Pn*TiMe(μ-Cl)]₂ proving crucial in the formation of [Pn*Ti(μ-Cl)]₂(μ-CH₂). <b>Chapter Three</b> describes the incorporation of classical organometallic ligands into the Pn*Ti moiety, including the first examples of benzyl, alkyl, aryl, allyl and η¹-Cp bound to a PnTi fragment. Seven complexes have been structurally characterised including the first ever crystal structure of a π-hydrocarbon bound Ti species bearing two CH₂^tBu groups, Pn*Ti(CH₂^tBu)₂, and the fluxional mixed hapticity complex Pn*Ti(η⁵-Cp)(η¹-Cp), whose η¹-Cp rearranges via a 1,2-sigmatropic shift. <b>Chapter Four</b> investigates the reactivity of the monomeric dialkyls, Pn*TiR₂ (R = Me, CH₂Ph, CH₂SiMe₃ and CH₂^tBu) with CO₂, CO and H₂. All four compounds demonstrate “normal” insertion of the CO₂ moiety into both Ti-R bonds, revealing a symmetrical bidentate coordination of the RCO₂ units. Computational studies have highlighted two competing pathways for their reaction with CO, dependent on the concentration of CO and size of R, which results either in formation of an enediolate or a titanoxirane. The reaction with H₂ yields the fascinating trimeric mixed valence, [Pn*Ti(μ₂-H)]₃(μ₃-H), the first structurally characterised example of a trimeric Ti-H species and the first to include a Ti-(μ₃-H) moiety. (Pn*TiCl)₂(μ-O) is formed by the action of adventitious H₂O and possesses a linear Ti-O-Ti bridge with a degree of Ti-O double bond character, supported by crystallographic data and DFT calculations. <b>Chapter Five</b> discusses ethylene polymerisation studies on the monomeric dialkyl complexes Pn*TiR₂ (R = Me, CH₂Ph, CH₂SiMe₃ and CH₂^tBu) using the activators [Ph₃C][B(C₆F₅)₄], [PhNMe₂H][B(C₆F₅)₄], AlⁱBu₃ and H₂. <b>Chapter Six</b> presents full experimental procedures for all of the syntheses and reactions outlined in Chapters Two to Five. <b>Chapter Seven</b> details characterising data for all novel compounds, and crystallographic data in the form of CIF files may be found in the electronic version.

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

Thesis (Ph. D.)--University of Missouri-Columbia, 1996. / Typescript. Vita. Includes bibliographical references (leaves 167-175). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1996. / Typescript. Vita. Includes bibliographical references (leaves 167-175). Also available on the Internet.

Call number: LD2668 .T4 1961 H64

No description available.