Includes bibliographical references. / 249 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, 1991

The synthesis and reactivity of a number of mixed transition metal-aluminium and σ-alane complexes are detailed in this thesis. Chapter III reports on the formation and structural characterisation of N,N'-chelated aluminium dihalide precursors featuring amidinate and guanidinate substituents. These precursors of the type RC(R'N)₂AlX₂ (R = ⁱPr₂N or Ph; R' = Cy or ⁱPr or Dipp; X = hal), readily react with Na[CpFe(CO)₂] via salt elimination to form the corresponding mixed iron-aluminium complexes CpFe(CO)2[(X)Al(NR')2CR] which have been characterised both spectroscopically and by X-ray diffraction. The reactivity of the novel mixed aluminium-iron complexes towards halide abstraction agents has been investigated and a propensity for augmented coordination at the aluminium centre observed. Furthermore, complementary syntheses of the methyl substituted complex CpFe(CO)₂[(Me)Al(NCy)₂CNⁱPr₂] have been developed. This can be achieved either via the reaction between the related chloride complex and MeLi, or from the reaction between ⁱPr₂C(CyN)₂Al(Me)Cl and Na[CpFe(CO)₂]. The research detailed in Chapter IV builds on the previous chapter and is focussed on the use of more sterically demanding substituents at both aluminium and transition metal, as well as more electron rich transition metal fragments. The transition metal anions Na[Cp*Fe(CO)₂] and Na[Cp^SiFe(CO)(PPh₃)] react with the aluminium precursors forming related mixed iron-aluminium complexes which have been structurally characterised. The Dipp₂NacNacAlCl₂ precursor has been shown to undergo reaction with both Na[CpFe(CO)₂] and Na[Cp*Fe(CO)₂]. The halide abstraction chemistry of the latter utilising both Lewis acid and salt metathesis based abstraction approaches has been investigated. The dehydrohalogenation chemistry of the Dipp₂NacNacAlCl₂ precursor was investigated and the ligand activated products of reactions with both alkyl lithium and alkyl potassium reagents characterised. Chapter V reports the extension of salt metathesis for the formation of an Al-H-Mn interaction, and the product has been fully characterised. In addition, the coordination of Al-H bonds from a number of alane precursors to in situ generated 16-electron fragments has allowed the structural characterisation of a number of novel σ-alane complexes. The incorporation of the transition metal fragments [Cp'Mn(CO)₂] and [W(CO)₅] permit comparison to archetypal borane and silane σ-complexes. Quantum chemical calculations suggest that the alane ligand has a binding energy close to that of dihydrogen but significantly less than that of CO, consistent with a predominant σ-donor role of the Al-H bond. The formation and structural characterisation of the κ²-complexes (OC)₄M[κ²-H₂AlDipp₂NacNac] (M = Cr, Mo or W) define an unprecedented binding motif for the alane ligand. In the cases of chromium and molybdenum the κ²-complexes can be prepared either photolytically or via alkene displacement from the corresponding (OC)₄M(cod) reagent. In the case of tungsten the alkene displacement route yields the desired product, but only under more forcing conditions. Spectroscopic characterisation of the related κ¹-complex (OC)₅Cr[κ¹-H₂AlDipp₂NacNac], which readily forms the κ²-complex in solution without photolysis, has enabled the kinetics of chelate ring closure to be investigated. This analysis further characterises the formation of the unprecedented κ²-binding motif for the alane ligand.

The research investigations presented herein are concerned with the syntheses and applications of arylboronic acids and their derivatives; with a particular focus on their accessibility or utility in certain of the most significant modern transition metal-catalysed reactions to involve organoborons. Chapter 1 provides an introduction to the field of organoboron chemistry, from its roots employing borane and related highly reactive derivatives for uncatalysed hydroboration of olefins and acetylenes, to the modern classes of organoboron reagents of the greatest significance to the related contemporary transition metal-catalysed methodologies. Furthermore particular emphasis is placed on the discussion of arylboronic acids, their synthesis, and application to transition metal catalysis as a result of their propensity to undergo useful transmetallation events. Chapter 2 details the use of a commercially available sulfonated monophosphine ligand in the rhodium-catalysed 1,2-addition reaction employing aryl aldehydes and arylboronic acids in aqueous media. The high and continued activity of the catalytic complex is demonstrated by it being successfully recycled five consecutive times in the arylation reaction of an aryl aldehyde; as well as being active for the arylations of more sterically demanding aryl methyl ketone substrates. Chapter 3 details the design and synthesis of a novel bench-stable azidomethylene substituted arylboronate ester. The reactivity of this compound and a related analogue in both the coppercatalysed azide alkyne cycloaddition reaction and the Suzuki coupling reaction are detailed, culminating in the proof-of-concept use of such versatile synthetic building blocks in the synthesis of a drug-substance derivative. Chapter 4 details alternative synthetic approaches to that used in Chapter 3 in order to access bifunctional azidomethylene substituted arylboronate esters. In particular the application of Miyaura borylation of arylhalides bearing benzylic azides is addressed as a means to rapidly access substrates which are otherwise shown to be incompatible with classical s-block synthetic intermediates.

Le cluster d’étain [(BuSn)12O14OH6]AMPS2 a servi de nanobrique pour l’élaboration de matériaux auto-réparants et themoformables. Le matériau hybride synthétisé est un élastomère capable de récupérer l’ensemble de ses propriétés mécaniques après avoir subi un endommagement mécanique, allant de la fissure de quelques μm à un endommagement drastique. En plus d’être réparable le matériau est recyclable, ce qui est un comportement exceptionnel pour un élastomère. Les liaisons ioniques entre le cœur du cluster et ses ligands qui connectent entre elles les chaînes macromoléculaires sont à la fois suffisamment fortes pour permettre de réticuler les chaînes et d’atteindre les propriétés d’un élastomère et suffisamment labiles pour permettre au réseau d’être dynamique. Les propriétés mécaniques des matériaux ont été évaluées mettant en évidence la nature dynamique du réseau à l’échelle macroscopique. La RMN DOSY a permis de mettre en évidence la dynamique dans le réseau à l’échelle moléculaire confirmant le rôle du cluster. Afin d’obtenir des matériaux avec des modules mécaniques élevés, des copolymères constitués de blocs rigides de polystyrène et de blocs souples de poly(acrylate de n-butyle) au sein duquel le cluster fonctionnel a été incorporé assurant la réticulation dynamique du matériau ont été synthétisé par polymérisation RAFT . Ces systèmes possèdent des propriétés de réparation thermostimulée, de thermoformage et peuvent être recyclés, contrairement aux élastomères thermoplastiques conventionnels. Cette stratégie de synthèse permet d’augmenter le module élastique G’ de 0,1 MPa pour l’élastomère à 500 MPa pour les copolymères tout en conservant un caractère dynamique. / A butyltin oxo-cluster macrocation, [(BuSn)12O14(OH)6]AMPS2, has been chosen as the Nano Building Block to create self-healing and malleable materials. The functional ligands enable the cluster to ionically cross-link poly(n-butyl acrylate) chains. The resulting hybrid material is an elastomer possessing properties which enable it to recover from damages: from a few μm depth cut to a dramatic failure. In addition, this material is recyclable, which is an exceptional property for an elastomer. The origin of the dynamic behavior is the ionic interaction between the cluster core and its ligands which are connected by macromolecular chains. Such interactions are strong enough to cross-link the polymer and consequently exhibit rubber-like elasticity behavior as well as render it labile enough to allow dynamic bond recombination leading to a dynamic network. Mechanical properties of the material (DMTA, Tensile Tests, and Relaxation Tests) have been evaluated and verify the macroscopic dynamic nature of the network. DOSY NMR experiments demonstrate the molecular dynamic of the networks, attesting the key role of the cluster. Concentrating on the development of high mechanical modulus materials with dynamic network, copolymers using hard blocks made of polystyrene and soft blocks of poly(n-butyl acrylate) which are cross-linked by the cluster have been synthetized. Such materials have thermo-stimulated healing properties, can be recycled, and are malleable, which is not the case for conventional thermoplastics. This synthesis strategy enables to raise the elastic modulus of the elastomer from 0.1 MPa to 500 MPa while maintaining the co-polymers dynamic properties.

Dans le cadre de nos travaux, nous avons développé une méthode extrêmement douce et particulièrement efficace d’accès à des γ-butyrolactones possédant un centre stéréogène quaternaire en α à partir d’énols carbonates d’allyle cycliques et exocycliques en utilisant la réaction d’alkylation allylique asymétrique décarboxylante pallado-catalysée (Pd-DAAA). Remarquablement, cette méthode a permis d’étendre l’utilisation de l’allylation asymétrique décarboxylante à des substrats sans précèdent dans la littérature, tels que les énols carbonates allyliques exocycliques. Cette réaction a été utilisée comme étape clé dans la synthèse des spirolactones chirales qui ont été obtenues avec de bons rendements et d’excellentes énantiosélectivités. Une nouvelle méthode catalytique robuste et hautement énantiosélective permettant d’accéder à des isoxazolidinones possédant un centre stéréogène quaternaire en α a été développée. Ce protocole repose sur une alkylation allylique asymétrique catalysée par des complexes de palladium chiraux (Pd-AAA) et amène aux produits désirés avec de bons rendements et d’excellents excès énantiomériques. Par ailleurs, nous avons également mis au point des conditions permettant de convertir ces isoxazolidinones α,α-disubstituées en acides β2,2 aminés et en β-lactames. / The development of a palladium-catalyzed decarboxylative allylic alkylation protocol (Pd DAAA) applied to cyclic and exocyclic allyl enol carbonates has allowed a highly enantioselective access to a range of γ butyrolactones bearing an all-carbon α quaternary stereogenic center. Remarkably, this approach allowed the extension of this reaction to substrates with no precedent in the literature, such as the exocyclic allyl enol carbonates. The Pd-DAAA process was eventually used for the synthesis of chiral spirolactones, which were readily obtained in high yields and in high optical purity. The synthesis of different isoxazolidin-5-ones bearing highly stereodefined all carbon α quaternary center was accomplished by palladium-catalyzed asymmetric allylic alkylation (Pd-AAA) of 4 substituted isoxazolidin-5-ones with an array of 2 substituted allyl acetates. The reaction proceeded in both excellent enantioselectivity and yield with isoxazolidin-5-ones containing an α-aryl substituents or an α heteroaryl moieties. This robust and highly enantioselective method allowed the access to valuable β2,2-amino acids and β lactams.

The structural chemistry and magnetic properties of compounds isostructural with La₁₈Li₈Rh₅O₃₉ have been studied. In this cubic structure (space group Pm^{^_}<sub style='position: relative; left: -.5em;'>3</sub>n), [111] chains of alternating RhO₆ octahedra (2a, 8e sites) and LiO₆ trigonal prisms (16i site) occupy channels within a La-O framework. In order to study the consequences of both reducing the dimensions of the channels and introducing paramagnetic cations into both the framework and the polyhedral chains, compositions in the series Nd₁₈Li₈Rh_5-xFe_xO₃₉ (1 &le; x &le; 4) have been synthesised and characterised by magnetometry, neutron diffraction and Mössbauer spectroscopy. Iron preferentially occupies the 2a site as low-spin Fe(IV) and the larger 8e site as high-spin Fe(III). Compositions having x > 1 show spin-glass-like behaviour below ~5 K. The behaviour of this series of compositions has been compared with that of the known series La₁₈Li₈Rh_5-xFe_xO₃₉. In order to facilitate this comparison, the structure of La₁₈Li₈Fe₅O₃₉ has been fully characterised by both neutron diffraction and EXAFS. The use of both techniques has revealed differences between the mean and local environments of iron. In order to explore and extend the range and combinations of elements that can be accommodated in this structure, the Ti-containing compounds Ln₁₈Li₈M₄TiO₃₉ (Ln=La,Nd,Pr,Sm; M=Rh,Fe,Co) have been synthesised. Nd₁₈Li₈Fe₄TiO₃₉ was selected for a detailed study by magnetometry, neutron diffraction, Mössbauer spectroscopy and XANES. Cations were found to be stabilised in unusual oxidation states and disordered over three sites of the Nd₁₈Li₈Fe₄TiO₃₉ polyhedral chains. The 8e site is occupied by high-spin Fe³⁺, Ti³⁺ and Li⁺ in a ratio of 76:20:4; the 2a site by low-spin Fe⁴⁺ and Ti⁴⁺ in a ratio of 79:21 and the trigonal-prismatic 16i site by Li⁺ and Fe³⁺ in a ratio of 98:2. Nd₁₈Li₈Fe₄TiO₃₉ undergoes a transition to a spin-glass state at 4.25(5) K, whereas La₁₈Li₈Fe₄TiO₃₉ revealed a different type of magnetic transition at ~8 K. The nature of this transition is not yet clear. Monophasic samples could not be prepared in the Nd/Rh system and cation vacancies were found in Nd/Co. No pure samples of Sm-containing compositions could be prepared, while the only Pr composition which was obtained pure, according to X-ray diffraction, Pr₁₈Li₈Co₄TiO ₃₉ shows the similar magnetic properties to Pr₁₈Li₈Co₃TiO₃₉. The compositions Ln₁₈Li₈M₃ M'O₃₉ (Ln=La,Nd,Pr,Sm; M,M'=Fe,Co,Ti) with 25% of the 8e sites vacant have been investigated. The Co-containing compositions Nd₁₈Li₈Co₃FeO_39-y, Nd₁₈Li₈CoFe₃O_39-y and Nd₁₈Li₈Co₃TiO_39-y were characterised by neutron diffraction. Cation vacancies on the 8e sites were found to coexist with anion vacancies around the 2a sites. The remaining octahedral sites are occupied by a disordered arrangement of transition-metal cations. The trigonal-prismatic sites are fully occupied by Li except in the case of Nd₁₈Li₈CoFe₃O_39-y where some Fe is present, as confirmed by Mössbauer spectral data. Antiferromagnetic interactions are present on the Nd sublattice in each composition, but a spin glass forms below 5 K when a high concentration of spins is also present on the octahedral sites. The magnetic character of the Ln cations plays an important role in determining the properties of these compounds. Long-range magnetic order of the transition-metal cations was not observed in any compositions. Although this might be partly attributable to the cation disorder in the polyhedral chains, the apparent antiferromagnetic behaviour of Nd-containing compositions in which the transition metals have a low magnetic moment, e.g. Nd₁₈Li₈Co₃TiO_39-y, and the marked contrast between certain La and Nd compositions in which the transition metal content is the same, e.g. Nd₁₈Li₈Fe₄TiO₃₉ and La₁₈Li₈Fe₄TiO₃₉, suggests that the Ln sublattice is fully involved in determining the magnetic behaviour.

Les polyoxométallates (POMs) de type Keggin [XM12O40]n- (avec X=P… et M= W, Mo …) sont des oxydes moléculaires de métaux de transition à haut degré d’oxydation qui présentent des réductions successives et réversibles dans une gamme étroite de potentiel. Leur incorporation dans des dispositifs de mémoire moléculaire semble alors prometteuse. Nous avons développé leur intégration comme briques élémentaires via une approche “bottom-up” qui surmonte les limites de l’approche “top-down” plus commune. Cela nécessite un contrôle fin de leur greffage et de leur densité surfacique pour l’obtention de dispositifs performants. Nous avons donc développé le greffage covalent de POMs sur des surfaces à base de silicium et d’or. Des hybrides de POMs à terminaison diazonium BA3[PM11O39{SnC6H4C≡CC6H4N2}] (avec M=W or Mo) ont formé des monocouches complètes greffées sur des surfaces de silicium hydrogénées qui mettent en évidence l’influence du métal constitutif du fragment polyoxométallate sur les propriétés de transport de charges de la jonction. Le greffage d’hybrides de POM à terminaison acide carboxylique sur des substrats d’oxyde de silicium a aussi été développée. Un hybride de POM à terminaison aniline TBA4[PW11O39{SnC6H4C≡CC6H4NH2}] a été greffé en deux étapes via un couplage peptidique sur une monocouche à terminaison acide carboxylique sur surface d’or. Des monocouches compactes ont été obtenues mais pas de façon totalement reproductible et les premiers essais de dilution sont encourageants. Une nouvelle famille d’hybrides de POMs mixtes a été synthétisée : TBA4[PMoxW11-xO39{SnR}]. Cela permettra de combiner les propriétés redox du molybdène et la robustesse due au tungstène. / Keggin type polyoxometalates (POMs) [XM12O40]n- (with X=P… and M= W, Mo…) are molecular oxides of early transition metals with a high oxidation state. They present electrochemical successive reversible reduction waves in a narrow range of potential. This makes them good candidates to be incorporated into molecular memory devices. We chose a “bottom-up” approach where the POMs are the building blocks to overcome the limitation of the “top-down” process commonly used. A fine control of the POM grafting and of the surface density is essential to get better erase/writing time of the device. So, we developed POM hybrids for grafting them covalently onto silicon based and gold substrates. Diazonium-terminated POM hybrids (with M=W or Mo) lead to compact homogeneous monolayers onto hydrogenated silicon surfaces. Electrical measurements of the two analogous modified surfaces show different behaviour highlighting the role of the constituting POM metal into the charge transport. Carboxylic-terminated POM hybrids have also been grafted in a one-step process onto silicon oxide surface resulting in a smooth and dense monolayer. Then, an aniline-terminated POM hybrid has been grafted onto a carboxylic-terminated SAM of thiols onto gold thanks to a peptide coupling. Compact monolayers have been obtained without complete reproducibility and the first attempts of dilution are encouraging. A new family of POM hybrids have been synthesized: mixed-metal POM hybrids TBA4[PMoxW11-xO39{SnR}]. This will permit to combine the electrochemical properties of molybdenum and the robustness of tungsten.

La conception et la réalisation d’architectures moléculaires de type [Mx(μ-L)yL’z]n, où μ-L est un ligand pontant, L’ un ligand terminal, n la charge et M un ion métallique de transition, sont attrayantes de part leurs richesses dans le domaine de la chimie de coordination mais aussi pour leurs applications potentielles dans des domaines tels que le magnétisme, l’optique ou encore la catalyse. Le ligand terminal qui a été choisi pour ce travail est un macrocycle, appelé p-tert-butylsulfonylcalix[4]arène, formé d’unités phénoliques reliées entre elles par des groupements sulfonyle. Dans un premier temps, une famille de complexes tétranucléaires de Mn2+ a été obtenue et caractérisée. Ces agrégats ont présenté des propriétés optiques de luminescence originales, à l’état solide et en solution. La photo-réaction, en solution de ces clusters, a permis de mettre en évidence le premier complexe stable mononucléaire de Mn3+/p-tert-butylsulfonylcalix[4]arène. La photo-réactivité de ces complexes, a révélé pour la première fois, la dynamique moléculaire que ce ligand pouvait avoir sous une excitation lumineuse. Puis, les réactions faites avec l’ion Mn2+ ont été transposées sur l’ion Co2+. La réactivité différente de cet ion, a permis d’isoler différents agrégats de structures moléculaires originales. Certains ont présenté des propriétés de « single ion magnet » (SIM). Enfin, des études sur la modification du p-tert-buytlthiacalix[4]arène ont débouché sur la mise au point de la première méthode générale de mono-O-alkylation de ce type de macrocycle. / The realization of molecular architectures type [Mx(μ-L)yL’z]n; (with μ-L a chelating ligand, L’ a terminal ligand, n a charge and M a metallic transition ion) are attractive because of their potential applications in many domains such as magnetism, optics and catalysis.The terminal ligand which was chosen for this work is a macrocycle, called p-tert-butylsulfonylcalix[4]arene formed by phenolic units connected between them by sulfonyle groups.Firstly, a family of tetranuclear manganese (II) complexes was obtained and characterized. These clusters presented original optical properties of luminescence, in solid state and in solution.In solution, the photo-reaction of these clusters allowed to obtain the first stable ever mononuclear complex Mn3+/p-tert-butylsulfonylcalix[4]arene. Photo-reactivity of these complexes revealed that this ligand could have a molecular dynamics under a light irradiationThen the reactions made with ions Mn2+ were transposed for ions Co2+. Reactivity of Co2+ allowed to isolate various clusters with original molecular structures. Some presented properties of “Singles Ions Magnets”Finally, studies on the modification of p-tert-butylthiacalix[4]arene enabled us to design the first general method of mono-O-alkylation of this macrocycle type.

L’utilisation des combustibles fossiles est responsable de l’augmentation de la concentration en gaz à effet de serre dans l’atmosphère. Parmi les solutions de remplacement envisagées, l’hydrogène constitue un vecteur d’énergie très intéressant. Toutefois, cette solution ne sera envisageable que lorsque les problématiques liées à la production de l’hydrogène et à son stockage seront résolues.Le premier objectif de cette thèse porte sur la synthèse et la caractérisation de composés ternaires à base de magnésium dans le système ternaire TR-M-Mg (avec TR = Terres Rares et M = métaux de transition) qui pourraient être de bons candidats pour le stockage de l’hydrogène. Ces composés pourraient de plus avoir d’autres applications, notamment comme matériaux de structure, du fait de leur très faible densité. La composition NdNiMg15 a fait l’objet d’une étude complète. Cette phase cristallise selon une symétrie quadratique avec a= 10,0602(1) et c= 7,7612(2) Å et un groupe d’espace P4/nmm. Un ordre antiferromagnétique à 9 K est observé et la capacité massique de stockage réversible est de 4 %mass. Cette nouvelle phase a montré un effet durcissant sur le magnésium.Le deuxième objectif de cette thèse concerne la production d’hydrogène par hydrolyse i) des composés ternaires TR-M-Mg qui pourrait être considérée comme une possibilité économique et énergétique pour valoriser les déchets de ces composés et ii) des mélanges ternaires TR-M-Mg élaborés par broyage mécanique. Le broyage a permis la création des défauts favorisant ainsi la corrosion des métaux. De plus, la production d'hydrogène par hydrolyse des composites Mg-NdNiMg15 (70, 80 et 90 %mass. Mg) a été réalisée et comparée à celle du composé NdNiMg15 (64 %mass. en Mg). Le mécanisme de corrosion principal déduit des essais électrochimiques sur les composites est la corrosion galvanique. / The use of fossil fuels (non-renewable energy) is responsible for the increase of the concentration of greenhouse gases in the atmosphere. Among the considered alternatives, hydrogen is seen as the most attractive energy vector. Production and storage of hydrogen is one of the key challenges in developing the hydrogen economy.The first objective of this thesis deal with the synthesis and characterization of magnesium-based ternary compounds in the RE-TM-Mg ternary system (with RE = Rare Earth and TM = transition metals) which could be good candidates for hydrogen storage. These compounds could also have other applications than the hydrogen storage in the future such as light structured material. The NdNiMg15 compound has been the subject of a completed study. This phase crystallizes with a tetragonal symmetry (a= 10.0602(1) and c= 7.7612(2) Å and a space group P4/nmm). It showed an antiferromagnetic ordering at 9 K and a reversible hydrogen storage capacity of 4 %mass. This phase exhibited a hardening effect respect to magnesium compound.The second objective of this thesis concerns the hydrogen production by hydrolysis of i) RE-TM-Mg ternary compounds, which could be considered as an economic and energetic possibility to valorize the waste of these compounds and ii) RE-TM-Mg ternary mixtures prepared by ball milling. The grinding creates defects thus promoting the corrosion of the metals. In addition, the hydrogen production by hydrolysis of the Mg-NdNiMg15 composites (70, 80 and 90 %mass. Mg) was carried out and compared with that of the NdNiMg15 compound (64 %mass. Mg). The main corrosion mechanism determined from the electrochemical measurements of the composites is the galvanic corrosion.

This Thesis describes the synthesis and characterisation of new alkaline earth- and rare earth-transition metal complexes. Experimental and computational studies were performed to investigate the structure and bonding in these complexes. Their reactivity was also studied. Chapter 1 introduces metal-metal bonded complexes and current alkaline earth- and rare earth-transition metal bonded complexes. Chapter 2 describes experimental and computational studies of new alkaline earth- and lanthanide-Fe complexes possessing the [CpFe(CO)2]- anion. Chapter 3 presents experimental studies of the reduction of Fe3(CO)12 with Ca. Chapter 4 describes experimental and computational studies of new alkaline earth- and lanthanide-Co complexes containing the [Co(CO)3(PR3)]- anion. Chapter 5 presents full experimental procedures and characterising data for the new complexes reported. Appendix describes the attempted synthesis of [Ca{CpRu(CO)2}2(THF)x]y and study by DFT of [CaRp2(THF)3]2 CD Appendix contains .cif files for all new crystallographically characterised complexes described.