A series of multidentate N-donor ligands have been synthesised all containing pyridyl and pyridyl/thiazole units and their coordination behaviour is described. The ligands are classified into four types; i) terpyridine containing pyridyl/thiazole ligands (L1-3); ii) pyridyl/thiazole ligands containing a 3,3′-disubstituted bipyridine core. (L4-8); iii) 2,2′-bipyridine containing a crown ether moiety (L9-11); and iv) a 2,2′- bipyridine derived ligand containing a urea functional group in the 3,3′-positions (L12). Chapter II describes terpyridyl/pyridyl/thiazole ligands: - the synthesis of (L1-3) is described and the complexes ([Cu(L1)][ClO4]2, [Ni(L2)][ClO4]2, [Co(L2)][ClO4]2, [Cd3(L3)2][ClO4]6) structurally characterised. Partitioning of the ligands (L1-3) is dependant on the position of the thiazole ring within the ligand chain. This partitioning is found to occur at a position adjacent to that of the thiazole ring in all but the L2 ligand complexes, where it is partitioned preferentially at a position creating favourable coordination geometry for the metal ion. Chapter III describes 3,3′-disubstituted pyridyl/thiazole ligands (L4-8): - the novel potentially hexadentate ligands (L4, 5), the potentially octadentate ligand (L6) and the potentially tetradentate ligands (L7, 8) have been synthesized and structurally characterised. All ligands are found to partition at the central pyridine unit due to unfavourable steric interactions to form a pyridyl/thiazole/pyridyl-binding domain (L4-6) and the pyridyl/thiazole-binding domain (L7,8). The substituents are found to dominate the control of the formation of complexes produced ([Zn(L4)][ClO4]2, [Cd(L5)][ClO4]2, [Cd2(L6)2][ClO4]2, [Cd2(L8)2][ClO4]2). Chapter IV, Section 1 describes ditopic bipyridine/crown ether ligands: - the synthesis of (L9-11) is described and the Ru (II) complexes (L9-11) structurally characterised. The Ru(II) complexes of these 3,3′-disubstituted crown ether species were found to luminesce. Modulation of the luminescent properties of the ruthenium complex was investigated with a selection of common cations but resulted in little or no response. Chapter IV: - Section 2- Ditopic bipyridine/urea ligands: - the novel ligand containing urea substituent side chains (L12) has been synthesised and a ligand containing both pyridine and urea substituents has been synthesised and characterised. A ruthenium complex (X) was synthesised with ligand (L12) and (bipy)2RuCl2, the resulting structure confirmed via 1H & 13C NMR as well as electrospray mass spectrometry (ESI-MS). Unfortunately no complexes have been structurally characterised due to the instability and decomposition of the complex after a short period of time. The ruthenium complex however was found to luminesce; ligand/anion recognition studies with complex (X) and a selection of common anions showed a marked change, a ten fold increase in the luminescence was observed with the addition of H2PO4 - when in a non-aqueous solvent.

This thesis describes the synthesis, characterisation and coordination chemistry of a variety of fluorinated ß-diketonate ligands (I) and carboxylate ligands (II), the catalytic activity of the resultant metal complexes for oxidation and C-C bond forming reactions, and an evaluation of fluorous methodologies for catalyst/product separation. (Fig. 3706) Chapter 1 introduces the concept and application of fluorous methodologies, including fluorous biphase catalysis and fluorous reverse phase silica gel (FRPSG), as alternative approaches to product/catalyst separation in homogeneous catalysis. Chapter 2 describes the synthesis and characterisation, in some cases by X-ray diffraction, of the fluorinated ß-diketonate ligands and an evaluation of the influence of the perfluoroalkyl groups on the coordination of these ligands to a variety of transition metals including copper, nickel, palladium and zinc. Chapter 3 outlines attempts to sue fluorous nickel ß-diketonate complexes for the oxidation of sulfides. The results indicate that a metal catalyst is not necessary for oxidation in this system although the veracity of catalyst separation using FRPSG was established. This chapter also describes the investigation of a fluorous molybdenum ß-diketonate complex for the oxidation of alkenes, although the extreme moisture senstiviity of the complex negated any attempts at recovery and recycling. The scope of Lewis acid catalysed coupling of ß-diketones with cyanoformates and the ability to reuse and recycle the fluorinated ß-diketonate catalysts is described in chapter 4. Chapter 5 describes attempts to extend this efficient separation procedure to the C-C bond forming reactions of rhodium carboxylate dimers. Although catalysis was observed, catalyst/product separation using FRPSG was unsuccessful. Chapter 6 summarises all the experimental details and spectroscopic data, whilst a CD-rom includes all of the crystallographic data.

Bibliography: leaves 132-147 / ix, 147 leaves : ill ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Physical and Inorganic Chemistry, 1987

This Thesis describes the synthesis and characterisation of titanium imido compounds supported by pendant arm functionalised amidinate ligands. Reactivity studies of cyclopentadienyl amidinate-imido compounds with CO2 are presented. Chapter 1 introduces transition metal imido chemistry, with a particular emphasis on imido complexes of titanium. Chapter 2 describes recent developments in the chemistry of functionalised amidinate ligands. The synthesis and characterisation of new titanium imido compounds with pendant amine functionalised amidinate ligands is described. The preparation of an amidinate ligand with a pendant propyl arm is reported. Reactions of a selection of these complexes with small molecules are presented. Chapter 3 reviews recent developments in the chemistry of cyclopentadienyl amidinate-imido compounds. The preparation of cyclopentadienyl-supported titanium imido compounds bearing pendant arm amidinate ligands is described andthereactionsofthesecompoundswithCC>2arediscussed. Kineticanddensity functional theory studies of these reactions are presented. Chapter 4 describes the synthesis and characterisation of alkyl and aryloxide titanium amidinate-imido compounds. The preparation of cationic derivatives is also described and reactions of these cationic derivatives with small molecules are discussed. Chapter 5 presents full experimental procedures for all of the syntheses and reactivity studies outlined in Chapters 2 to 4. Chapter 6 contains characterising data for all of the new compounds reported. Appendices A - K contain tables of selected crystallographic data for all new crystallographically characterised complexes described in this Thesis. Appendices L - O contain kinetics data relating to work discussed in Chapter 3.

Bibliography: leaf 179 / 179 leaves : ill ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--Dept. of Physical and Inorganic Chemistry, University of Adelaide, 1986

Includes bibliographies / x, 149 leaves : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, 1986

The storage of nuclear waste in deep geological formations is discussed worldwide as the main strategy for nuclear waste management. To ensure the confinement of the nuclear waste, a multiple barrier system which consists of engineered, geo-engineered, and geological barriers will be applied. Thereby, in Germany the definition of the isolating rock zone represents an important safety function indicator. Clay rock is internationally investigated as potential host rock for a repository and represents a part of the geological barrier. In the present work, the natural clay rock Opalinus Clay from the Mont Terri rock laboratory, Switzerland, was studied. In Germany, the direct disposal of the spent nuclear fuel without the reprocessing of the spent fuel is preferred. In case of water ingress, radionuclides can be released from the nuclear waste repository into its surroundings, namely the host rock of the repository. Humic acids, ubiquitous in nature, can be found associated with the inorganic components in natural clay rock (1.5×10–3 wt.% in Opalinus Clay). They can be released under certain conditions. Due to their variety of functional groups, humic acids are very strong complexing agents for metal ions. They have inherent redox abilities and a colloidal conformation in solution. Because of these characteristics, humic acids can affect the mobility of metal ions such as actinides. Furthermore, in the near-field of a repository elevated temperatures have to be considered due to the heat production resulting from the radioactive decay of the various radionuclides in the nuclear waste. This work focuses on the interaction of uranium, as main component of spent nuclear fuel, with Opalinus Clay and studies the influence of humic acid and elevated temperature on this interaction. For investigation of the retention behavior of the clay and the mobility of U(VI) in the system, batch sorption and diffusion experiments were performed. To clarify which U(VI) and humic acid species were present under the applied conditions, aqueous speciation modeling was used. Additionally, the U(VI) speciation in solution and on the clay surface was investigated by spectroscopic methods. Prior to the investigation of the ternary system U(VI) / humic acid / clay, the applied batches of Opalinus Clay were characterized (e.g., specific surface area, carbon content, cation exchange capacity, elemental composition, particle size distribution). Leaching studies with Opalinus Clay in synthetic Opalinus Clay pore water (pH 7.6, It = 0.34 mol/L) and in NaClO4 (pH 3 – 10, I = 0.1 mol/L) were performed to identify the competing ions and their concentrations in the background electrolytes. These data were used to calculate the U(VI) and humic acid speciation in solution. Calcium and carbonate ions are present under pore water conditions as well as in 0.1 mol/L NaClO4 from pH 7 to 8.5, due to dissolution of calcite (mineral fraction in Opalinus Clay). Thus, the U(VI) speciation is dominated by the aquatic Ca2UO2(CO3)3 complex. In the case of pore water, Ca2UO2(CO3)3(aq) is also the dominant U(VI) species in the presence of humic acid, which was corroborated by time-resolved laser-induced fluorescence spectroscopic measurements. A significantly changed speciation was found in 0.1 mol/L NaClO4 in the presence of humic acid. At pH > 7, the negatively charged UO2(CO3)2HA(II)4– complex determines the U(VI) speciation, thus repressing the Ca2UO2(CO3)3(aq) complex. In addition, the speciation of humic acid is influenced from ions leached out from Opalinus Clay. The CaHA(II) complex is the dominating humic acid species in solution. Batch sorption experiments in 0.1 mol/L NaClO4 showed that Opalinus Clay has the strongest retardation effect on U(VI) in the pH range from pH 4.5 to 7. However, under environmentally relevant conditions (pH > 7), the sorption of U(VI) onto Opalinus Clay is very weak. Under pore water conditions, a distribution coefficient (Kd) of 0.0222 ± 0.0004 m3/kg was determined, which was shown to be independent of solid-to-liquid ratios ≥ 60 g/L. In addition, in pore water, the U(VI) sorption onto Opalinus Clay is not influenced by humic acid, which is supported by the speciation results. Extended X ray absorption fine-structure investigations confirmed this batch sorption result. The U(VI) diffusion experiments performed in pore water at 25 °C with Opalinus Clay bore core samples confirmed the Kd value obtained by batch sorption experiments. In the diffusion experiments at 60 °C, a change in the U(VI) speciation occurred. Beside Ca2UO2(CO3)3(aq), a colloidal U(VI) species was formed. Almost equivalent apparent diffusion coefficient (Da) values were determined for the diffusion of the aqueous U(VI) species at 25 and 60 °C through Opalinus Clay. Thus, based on the investigations in the present study the breakthrough of U(VI) through Opalinus Clay is expected to be independent of the temperature and should occur nearly at the same time. Modeling calculations showed that it would take about 10 years until a detectable amount of 233U(VI) (1×10–9 mol/L) migrates through an 11 mm thick Opalinus Clay sample. Two distinct humic acid size fractions – a large- and a small-sized colloid fraction – diffused through the Opalinus Clay samples. Within three months, the high molecular size humic acid colloids migrated only about 500 µm into the clay, whereas the low molecular size fraction diffused through the entire Opalinus Clay samples and were consequently detected in the receiving reservoirs. These findings demonstrate a filtration effect of the compacted clay. The diffusion experiments revealed that the effect of humic acid on U(VI) diffusion is negligible and, under the studied conditions, independent of temperature. The obtained results contribute to data bases used for modeling of interaction and migration processes in uranium / clay rock systems. Thus, the collected sorption and diffusion data are not only relevant for safety assessment of nuclear waste repositories but also for any clay-containing system present in the environment, where the geochemical interaction with uranium contaminated water plays a role. Concerning the suitability of Opalinus Clay as host rock for a nuclear waste repository, it can be concluded, that Opalinus Clay has a relatively high retardation potential for U(VI). In case of water ingress U(VI) as part of the nuclear waste is released into the clay formation. Under near-neutral pH conditions, it will be complexed by calcium and carbonate ions leached out from Opalinus Clay, whereby Ca2UO2(CO3)3(aq) is formed. This complex is only weakly retarded by sorption onto the clay, which can contribute to an enhanced mobility of U(VI) in the host rock. However, the U(VI) migration through the clay rock is governed by molecular diffusion. This decelerates the migration of Ca2UO2(CO3)3(aq) through Opalinus Clay and thus it represents the decisive retardation process in the investigated system. Additionally, under environmentally relevant conditions, humic acid has no significant influence on U(VI) / Opalinus Clay interaction even at an elevated temperature of 60 °C. This was shown by speciation, sorption, as well as diffusion experiments. / Eine weltweit diskutierte Strategie zum Umgang mit radioaktiven Abfällen ist deren Endlagerung in tiefen geologischen Formationen. Zur Abschirmung der Umwelt vor den schädlichen Einflüssen des radioaktiven Abfalls soll ein Multibarrierensystem bestehend aus technischen, geotechnischen und geologischen Barrieren im Endlager dienen. Dabei ist in Deutschland die Definition des einschlusswirksamen Gebirgsbereichs ein wichtiger sicherheitstechnischer Indikator. Tongestein wird als potentielles Endlagerwirtsgestein und Teil der geologischen Barriere international erforscht. In der vorliegenden Arbeit wurde das natürliche Tongestein Opalinuston aus dem Mont Terri Felslabor, Schweiz, untersucht. In Deutschland wird die direkte Endlagerung des abgebrannten Kernbrennstoffes ohne Wiederaufarbeitung des Brennstoffs favorisiert. Bei Wassereinbruch können Radionuklide aus dem Abfall in die Umgebung des Endlagers freigesetzt werden, d. h. sie können in Kontakt mit dem Wirtsgestein kommen. Ubiquitär in der Natur vorkommende Huminsäuren können mit den anorganischen Komponenten des natürlichen Tongesteins vergesellschaftet sein (1.5×10–3 Gew.-% in Opalinuston). Unter bestimmten Bedingungen können die Huminsäuren freigesetzt werden. Ihre Struktur enthält eine Vielzahl von funktionellen Gruppen, was sie zu starken Komplexbildnern für Metallionen macht. Sie besitzen Redoxeigenschaften und bilden in Lösung eine kolloidale Konformation aus. Aufgrund dieser Charakteristika können sie die Mobilität von Metallionen wie den Actinoiden beeinflussen. Weiterhin sind im Nahfeld eines Endlagers erhöhte Temperaturen zu erwarten, welche aus der Wärmefreisetzung beim radioaktiven Zerfall der verschiedenen Radionuklide im radioaktiven Abfall resultieren. Die vorliegende Studie konzentriert sich auf die Untersuchung der Wechselwirkung von Uran, als Hauptkomponente des endgelagerten abgebrannten Kernbrennstoffs, mit Opalinuston und untersucht dabei den Einfluss von Huminsäure und erhöhter Temperatur. Um das Rückhaltevermögen des Tongesteins gegenüber U(VI) und die U(VI)-Mobilität im System zu ermitteln, wurden Sorptions- und Diffusionsversuche durchgeführt. Zur Klärung, welche U(VI)- und Huminsäurespezies unter den untersuchten Bedingungen vorliegen, wurde die aquatische Speziation berechnet. Zusätzlich wurde die U(VI)-Speziation in Lösung und an der Tonoberfläche mit spektroskopischen Methoden untersucht. Vor der Untersuchung des ternären Systems U(VI) / Huminsäure / Ton wurden die eingesetzten Opalinuston-Chargen charakterisiert (z. B. spezifische Oberfläche, Kohlenstoffgehalt, Kationenaustauschkapazität, elementare Zusammensetzung, Partikelgrößenverteilung). Anschließend wurden Auslaugungsversuche mit Opalinuston in synthetischem Opalinustonporenwasser (pH 7.6, It = 0.34 mol/L) und in NaClO4 (pH 3 – 10, I = 0.1 mol/L) durchgeführt, um relevante Konkurrenzionen zu identifizieren und deren Konzentration in den Hintergrundelektrolyten zu bestimmen. Die erhaltenen Daten wurden zur Berechnung der U(VI)- und Huminsäurespeziation in Lösung verwendet. Unter Porenwasserbedingungen sowie in 0.1 mol/L NaClO4 von pH 7 bis 8.5 liegen, durch die Auflösung von Calcit (Mineralphase im Opalinuston), Calcium- und Carbonationen in Lösung vor. Dadurch wird die U(VI)-Speziation von dem aquatischen Ca2UO2(CO3)3-Komplex dominiert. Im Falle des Porenwassers ist Ca2UO2(CO3)3(aq) auch in Gegenwart von Huminsäure die dominierende U(VI)-Spezies. Dies wurde durch zeitaufgelöste laserinduzierte fluoreszenzspektroskopische Messungen nachgewiesen. Eine signifikante Änderung der U(VI)-Speziation tritt in 0.1 mol/L NaClO4 in Gegenwart von Huminsäure auf. Bei pH > 7 bestimmt der negativ geladene UO2(CO3)2HA(II)4–-Komplex die U(VI)-Speziation, wobei der Anteil von Ca2UO2(CO3)3(aq) zurückgedrängt wird. Auch die Huminsäurespeziation wird durch die vom Opalinuston ausgelaugten Ionen beeinflusst. So ist der CaHA(II)-Komplex die dominierende Huminsäurespezies in Lösung. Sorptionsversuche in 0.1 mol/L NaClO4 zeigten, dass Opalinuston gegenüber U(VI) den stärksten Retardationseffekt im pH-Bereich 4.5 bis 7 aufweist. Unter umweltrelevanten Bedingungen hingegen (pH > 7) ist die U(VI)-Sorption an Opalinuston sehr schwach. Unter Porenwasserbedingungen wurde ein Verteilungskoeffizient (Kd) von 0.0222 ± 0.0004 m3/kg ermittelt, der von Fest-Flüssig-Verhältnissen ≥ 60 g/L unabhängig ist. Außerdem wird die U(VI)-Sorption an Opalinuston in Porenwasser nicht von Huminsäure beeinflusst. Dies wird durch die Ergebnisse aus den Speziations-rechnungen unterstützt. Röntgenabsorptionsspektroskopische Untersuchungen bestätigten ebenfalls dieses Sorptionsergebnis. Die U(VI)-Diffusionsexperimente in Porenwasser bei 25 °C unter Verwendung von Opalinustonbohrkernstücken bestätigten den Kd-Wert der Sorptionsexperimente. In den Diffusionsexperimenten bei 60 °C trat eine Änderung in der U(VI)-Speziation auf. Neben Ca2UO2(CO3)3(aq) wurde eine kolloidale U(VI)-Spezies gebildet. Für die Diffusion der aquatischen U(VI)-Spezies durch Opalinuston bei 25 und 60 °C wurden annähernd gleiche scheinbare (apparente) Diffusionskoeffizienten (Da) bestimmt. Das bedeutet, der Durchbruch von U(VI) durch Opalinuston ist unabhängig von den hier untersuchten Temperaturen und wird deshalb etwa zum gleichen Zeitpunkt erwartet. Modellierungen zeigten, dass es etwa zehn Jahre dauern würde, bis eine detektierbare Menge an 233U(VI) (1×10–9 mol/L) durch ein 11 mm-dickes Opalinustonbohrkernstück migrieren würde. Zwei verschiedene Huminsäuregrößenfraktionen diffundierten durch die Opalinustonproben – eine große und eine kleine kolloidale Größenfraktion. Innerhalb von drei Monaten migrierten die hochmolekularen Huminsäurekolloide nur 500 µm in den Ton, während die niedermolekularen Huminsäurekolloide durch die gesamten Opalinustonproben diffundierten und dadurch im Auffangreservoir detektiert werden konnten. Diese Resultate demonstrieren den Filtrationseffekt des Tongesteins. Die Diffusionsversuche zeigten, dass der Einfluss von Huminsäure auf die U(VI)-Diffusion, unabhängig von der in dieser Arbeit verwendeten Temperatur, vernachlässigbar ist. Die erhaltenen Ergebnisse tragen zu Datenbanken bei, die für die Modellierung von Wechselwirkungs- und Migrationsprozessen in Uran / Tongestein-Systemen genutzt werden. Das bedeutet, die gesammelten Sorptions- und Diffusionsdaten sind nicht nur für den Langzeitsicherheitsnachweis eines Endlagers für radioaktive Abfälle von Relevanz, sondern auch für jedes tonhaltige System in der Umwelt, bei dem die geochemische Wechselwirkung mit urankontaminierten Wässern eine Rolle spielt. Bezüglich der Eignung von Opalinuston als Wirtsgestein für ein Endlager radioaktiver Abfälle lässt sich schlussfolgern, dass Opalinuston ein relativ hohes Retardationspotential bezüglich U(VI) aufweist. Wenn U(VI) als Bestandteil des radioaktiven Abfalls bei Wassereinbruch im Endlager in die Umgebung freigesetzt wird, wird es unter umweltrelevanten Bedingungen von Calcium- und Carbonationen, welche aus dem Opalinuston herausgelöst werden, komplexiert. Dabei bildet sich Ca2UO2(CO3)3(aq). Dieser Komplex wird nur schwach durch Sorption am Tongestein zurückgehalten, was zu einer erhöhten U(VI)-Mobilität im Wirtsgestein führen kann. Im untersuchten System wird die U(VI)-Migration durch das Tongestein jedoch durch molekulare Diffusion bestimmt. Sie verzögert die Migration von Ca2UO2(CO3)3(aq) durch Opalinuston und stellt somit den maßgeblichen Retardationsprozess im System dar. Huminsäure hat keinen signifikanten Einfluss auf die U(VI) / Opalinuston-Wechselwirkung, sogar bei einer erhöhten Temperatur von 60 °C. Dies wurde mittels Speziationsmodellierungen sowie durch Sorptions- und Diffusionsversuche gezeigt.

The reactivity of group 15 Zintl ions, E₇^3– (E = P, As), towards a number of transition and post-transition metal reagents has been studied. The synthesis and characterisation of the resulting novel cluster anions are described herein. The reactions of E₇^3– with [Cu₅(mes)₅], MPh₂ (M = Zn, Cd) and InPh₃ yielded the Cu–Cu bridged species [Cu₂(E₇)₂]^4– (E = P, As), the group 12 bridged cluster anions [M(E₇)₂]^4– (M = Zn: E = P, As; M= Cd: E = P), and the In-functionalised Zintl ions [E₇InPh<sub>2<sub>]^2–, respectively. P₇^3– and As₇^3– have been found to react with a number of metal salts, namely [M(nbe)₃][SbF₆] and MCl (M = Ag, Au), InCl₃, TlCl and MI₂ (M = Sn, Pb). These reactions formed the Ag–Ag and Au–Au bridged complexes [M₂(HP₇)₂]^2– (M = Ag, Au), the In-bridged species [In(E₇)₂]^3– (E = P, As), the Tl-derivatised Zintl ions [TlE₇]^2– (E = P, As), and the sixteen vertex cluster anions [ME₁₅]^3– (M = Sn, Pb; E = P, As). The reactivity of P₇^3– towards a series of group 8 compounds has also been studied. The reactions of P₇^3– with FeCl₂ and [Ru(PPh₃)₃Cl₂] produced [M(HP₇)₂]^2- (M = Fe, Ru). NMR studies showed that these species can be deprotonated to form [M(P₇)₂]^4– (M = Fe, Ru). These Fe and Ru complexes are isoelectronic with ferrocene. In addition, P₇^3– reacts with [Ru(COD)(η³-CH₂C(CH₃)CH₂)₂] to form [(C₄H₇)P₇Ru(COD)]^2–. Both P₇^3– and As₇^3– undergo transition metal mediated activation reactions in the presence of [Co(PEt₂Ph₂)(mes)₂], yielding [Co(η⁵-P₅){η²-HP₂(mes)}]^2– and [Co([η³-As₃){η⁴-As₄(mes)₂}]^2–, respectively.

The purpose of this project has been to expand the η8 binding mode of the permethylpentalene ligand into uranium, zirconium and hafnium chemistry. All three of these elements have shown intriguing, high-hapticity carbocyclic chemistry and, because of their relatively large size, are excellent candidates for the development of organometallic permethylpentalene chemistry. Chapter one of this thesis will review previous work on η n carbocyclic ring chemistry of these elements, where n = 6 - 8. This introduction will include the unsaturated rings systems where all the ,carbons are bonded to the metal centre, specifically η6 arene systems, η 7 cyclohept.atriene systems, and η 8 cyclooctatetraene and pentalene systems. Species of lower hapticity (e .g. the η 6 binding mode of cycloheptatriene) will not be covered but reviews, where available, will be referenced. Chapter two documents the successful synthesis and characterisation of η 8 permethylpentalene uranium (IV) species. Initially, the uranocene equivalent, UPn*2 was synthesised and characterised structurally, magnetically and electrochemically. From here, a half-sandwich synthon [U Pn*CI4][Li(TMEDA)h was synthesised which was used for further salt metathesis chemistry in order to make a number of mixed sandwich complexes. Chapter three is an account of the synthesis and characterisation of zirconium and hafnium η 8 permethylpentalene species. Initial work focused on the synthesis of a suitable synthon analogous to that used for the previously synthesised titanium species. However, this route was unsuccessful and an alternative species was formed, [MPn*(μ-Cl)3/2]2(μCl)2[Li(THF)x(Et2O)y]. This species could be made on a multi-gram scale and proved to be a sui table synthon for further synthesis. Salt metathesis reactions were undertaken and a number of new species were synthesised and characterised including mixed-sandwich, alkyl, aryl and allyl species. Chapter four reports the results of polymerisation testing that was undertaken for selected synthesised compounds. All compounds catalysed the formation of poly(ethylene), with the group 4 mixed sandwich species being particularly active catalysts. Two of the zirconium species, ZrPn*CpCI and ZrPn*Cp2 were therefore used for further optimisation experiments which were somewhat limited due to the high activity of the compounds. These were useful in gaining insight into conditions that should be investigated on a larger reaction scale. Chapter five gives the full experimental details for all the syntheses described in chapters two and three as well as details of instrumentation used for characterisation, and also gives the respective loadings of catalyst and co-catalyst employed in the polymerisation testing reported in chapter four. Chapter six presents the full characterisation data obtained for the compounds synthesised and the electronic appendix attached as a CD at the back of the thesis contains the crystal data .cif files and the DFT output files (.out). ,

Achiral wide bite angle ligands have been shown to be highly active and to induce excellent chemo- and regioselectivities in many homogeneously catalyzed reactions. However, only a few examples of chiral wide bite angle ligands are known so far. A diphenyl ether backbone was selected to allow maximum synthetic versatility and potential for a modular approach to design and synthesize such chiral diphosphorus ligands. Three synthetic strategies have been explored in this thesis: i) introduction of chiral substituents in the ligand backbone, ii) the use of P-stereogenic donor atoms and iii) the synthesis of chiral mixed-donor ligands bearing chiral auxiliary groups on the phosphorus atoms. Functionalization of the 3,3'-positions of 2,2'-bis(diphenylphosphino)diphenyl ether by carboxylic acid or ether auxiliaries was achieved via straightforward four-step routes to generate a library of ligands that were tested in various catalytic reactions. In the Pd-catalyzed asymmetric allylic alkylation of l,3-diphenyl-2-propenyl acetate and cyclohexyl-2-enyl acetate with dimethyl malonate the enantioselectivity was found to depend on the size of the chiral auxiliary introduced within the diphenyl ether backbone and its proximity to the phosphorus donor groups and hence to the active metal centre. Two types of mixed donor bidentate diphosphorus ligands based on the diphenylether backbone have been established, i.e. phosphine-phosphite and phosphine-phosphonite derivatives. A small ligand library bearing different chiral auxiliaries was accomplished via straightforward syntheses that enable derivatization of the respective phosphite and phosphonite moieties in the final step. In the Rh-catalysed hydrogenation of several benchmark substrates high conversion and moderate to high enantioselectivities (up to 97% for dimethyl itaconate) were obtained. The enantioselectivity was influenced by the size of the ortho-substituent on the chiral auxiliary group of the phosphite or phosphonite fragment. Two modular synthetic approaches for the preparation of novel wide bite angle diphosphine ligands containing stereogenic P-atoms have been developed. Both protocols involved diphenylether as backbone and the chiral ephedrine based precursor (2R[subscript(P)],4S[subscript(C)],5R[subscript(C)])-oxazaphospholidine borane as initial auxiliary to induce chirality at phosphorus. Various novel diphosphines were isolated as highly enantioenriched compounds with dr-ratios up to 95:5.