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This dissertation comprises the investigation of two subjects in the field of dimetal paddlewheel-type compounds containing metal-metal bonds: unsolvated transition metal carboxylates and triply bonded divanadium compounds. The first subject is very mature; dichromium tetraacetate was first synthesized in 1844, and hundreds of dimetal tetracarboxylates have been structurally characterized to date. A general question concerning the complexes of the type M2L4-Xn (where n = 0 to 2) is the extent to which the M-M distances are influenced by the presence of axial ligands, X. However, virtually none of the carboxylato complexes crystallize without axial ligands. In the solid state, in the absence of a coordinating solvent, the dimetal units often act as axial ligands to one another. In order to exclude axial coordination, both from donor solvent molecules, and from the aggregation of M24+ units, we have successfully used the bulky 2,4,6-triisopropylbenzoate ligand to bridge the dimetal core. We have investigated the triisopropylbenzoato complexes of some metals which are known for their ability to form a vast array of tetracarboxylato complexes, namely chromium, copper, molybdenum, and rhodium, and have found that these novel compounds display some interesting structural and chemical properties. The second subject of this dissertation is much more contemporary. Although compounds containing multiple bonds between metal atoms have been known since 1964, the first triply-bonded divanadium compound was not synthesized until 1992, and only two additional compounds of this type have been made in the intervening ten years. In order to extend this chemistry, several additional compounds containing a triply bonded V24+ core have recently been characterized. In our study of these compounds, we have discovered the first example of a stable paddlewheel-type compound with a M23+ core.

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A study was undertaken to investigate the solid-state structure of about 25 triphenyltin carboxylates, Ø₃SnOCOR. The compounds were synthesized and then analyzed by Mössbauer and infrared spectroscopy. The compounds were divided into three series on the basis of the nature of the R group. The first series of compounds had R groups which were "linear" chain hydrocarbons ranging in length from one carbon atom (triphenyltin formate) to eighteen carbon atoms (triphenyltin stearate). In the second series several compounds had methyl branches at various positions along the hydrocarbon chain, some had longer alkyl groups and a few had a methylene group bonded to the a-carbon atom. The third series contained mono-, di-, and tri- substituted haloacetates. These compounds were prepared in order to test the assumption that bulky R groups would prevent (by steric interaction) polymer formation in the solid. The polymeric structure which is commonly found for triorganotin carboxylates consists of pentacoordinate Sn atoms. Each carboxylate group bridges between two different Sn atoms and this occurs indefinitely to form a polymer. Steric interaction of the R group with neighbouring phenyl groups (bonding to Sn) could prevent polymer formation. The resulting structure would be monomeric and have a tetracoordinate Sn atom and a terminal carboxylate group like that for an organic ester. The majority of compounds were found to be polymeric solids. Structural changes (polymeric to monomeric) were observed for a few compounds and this could be attributed to steric interaction. The Mössbauer and infrared data were complimentary and conclusive when used to differentiate between the two possible structural types. In a polymeric structure the Sn atom can be visualized as being in a trigonal bipyramidal environment in which the oxygen atoms are axial and the phenyl groups equatorial. Using the above idealized structural type it was possible to test a point-charge model which had been used to predict quadrupole splitting values, Δ. The model was tested for the triphenyltin haloacetates and found to give fairly good agreement with the observed quadrupole splitting values. / Science, Faculty of / Chemistry, Department of / Graduate

L'augmentation du prix des métaux associé au coût de l’enfouissement des déchets font que les industries se tournent de plus en plus vers la valorisation de leurs déchets. Le Laboratoire d’Electrochimie des Matériaux a démontré la possibilité de précipiter sélectivement les métaux contenus dans les effluents industriels liquides en utilisant des carboxylates de sodium préparés à partir d’acides carboxyliques d’origine naturelle (huiles végétales, graisses animales...). Afin de pouvoir utiliser les différents carboxylates de manière judicieuse, il est nécessaire de caractériser les produits obtenus. En effet, peu de données thermodynamiques sont disponibles dans la littérature. Pour envisager la séparation sélective de métaux par ces composés, il est nécessaire de déterminer la solubilité et le comportement thermique de chaque carboxylate métallique. Ainsi ce mémoire recense les résultats obtenus sur des carboxylates métalliques di- et trivalents mettant en jeu 11 cations métalliques (Ca2+, Cd2+, Co2+, Cr3+, Cu2+, Fe2+, Fe3+, Mn2+, Ni2+, Pb2+ et Zn2+) et 4 carboxylates de sodium (heptanoate, octanoate, nonanoate et décanoate) après vérification de la nature du solide par analyse chimique et DRX. L’obtention des valeurs de solubilité des décanoates métalliques a permis d’obtenir un diagramme de prévision de la faisabilité d’une séparation entre deux cations divalents. La séparation a ensuite été appliquée à un mélange Ni/Cd synthétique représentatif d’une problématique industrielle (lixiviat des batteries nickel – cadmium) puis sur lixiviat réel. La possibilité de remplacer le décanoate de sodium (en solution) par du décanoate de calcium (solide) a également été étudiée / Industrial wastes were more and more recycled because of the increase of metals prices associated to the cost of waste burying. The laboratoire d’Electrochimie des Matériaux showed the feasibility of selective precipitation using sodium carboxylates. Sodium carboxylates came from linear and saturated carboxylic acid product of natural origin (vegetable oil and animal fats). In order to use sodium carboxylates for selective precipitation, it was necessary to characterize metallic carboxylates. Few thermodynamic data are in the literature. The most important constants are solubility and thermal comportment: the first was used for the selective separation itself and the second for the valorisation of some precipitate. This work gathered obtained results for metallic carboxylates resulting from the precipitation of 11 cations (Ca2+, Cd2+, Co2+, Cr3+, Cu2+, Fe2+, Fe3+, Mn2+, Ni2+, Pb2+ and Zn2+) with 4 sodium carboxylates (heptanoate, octanoate, nonanoate and decanoate). Before characterization, a chemical analyse and XRD were performed on each solid to determine their natures. The superimposing of solubility curves gives a tool allowing predicting the feasibility of a separation from a theoretical point of view. We studied the possibility to separate nickel and cadmium using sodium decanoate. This mixture corresponds to a real industrial problem (leaching of nickel/cadmium batteries). Precipitation was performed on synthetics solutions then on a real leaching. Another reagent was also studied: calcium décanoate which are solid at room temperature

Ce travail de thèse décrit la synthèse, l’étude cristallochimique et le comportement thermique de polymères de coordination à base de cations uranyle, ou mixtes uranyle-lanthanide complexés par des ligands carboxylates aromatiques (acide phthalique et dérivés). L’emploi de 7 molécules polycarboxylates a conduit à la formation de plus de 25 nouveaux composés type Uranyl-Organic Framework (UOF) ou hybrides uranyle-organique, ou encore mixtes uranyle-lanthanide-organique. Certains de ces ligands on montré une grande diversité d’arrangements atomiques, avec par exemple, l’isophthalate qui conduit à la formation de 10 complexes de coordination, alors que d’autres (par exemple terephthalate) ont permis d’isoler un seul type d’assemblage. Certaines de ces phases contiennent classiquement des briques de construction inorganiques monomériques ou tétramériques alors que d’autres mettent en évidence des blocs trimériques linéaires ou octamériques originals, ou encore des systèmes de chaînes inorganiques générant des structures à tunnels inédits. Une configuration rare d’interaction cation-cation (CCI ou U=O-U) a été également identifiée dans l’isophthalate à base d’unité octamérique. La synthèse de toutes ces phases a permis une meilleure compréhension des réactions hydrothermales et de l’influence de différents paramètres influant la formation du produit final. Pour les phases obtenues sous formes pures, les comportements thermiques et leur stabilité ont été étudiés. Ces expériences ont permis d’établir des relations entre le précurseur initial, la dégradation thermique et les conditions de formation de l’oxyde final. Les spectres de fluorescence ont été collectés et indiquent des informations sur l’influence de la nature du ligand organique ou du type du motif de construction inorganique. / This thesis work concerns the synthesis, crystal structural study and thermal behavior of coordination polymers type uranyl and mixed uranyl-lanthanide aromatic carboxylates. Using a series of 7 aromatic carboxylate ligands, more than 25 new uranyl (so-called Uranyl-Organic Framework or UOF) and mixed uranyl-lanthanide coordination polymers have been synthesized and described in this manuscript. Some of the ligands have proven to be very prolific such as the isophthalic acid, which is present in 10 coordination polymers and with others (such as terephthalic acid) only one complex could be isolated. Some of the obtained phases contain typical monomeric or tetrameric SBUs and others possess unique features such as octanuclear SBU with an edge sharing CCI (U=O-U), linear trinuclear SBU or polymeric SBU delimiting large tunnel systems. The synthesis of all these phases conducted to a better understanding of the hydrothermal reactions and the influence of different parameters over the final reaction product. For each of the phases obtained pure the thermal behavior and thermal stability have been studied. These experiments offer a better understanding of the relation between the structure of the initial complex, the thermal degradation conditions and the nature of final oxide. Also for these phases the fluorescence emission spectra were recorded, offering information about the influence of different ligands or different type of SBUs over the typical uranyl spectrum.

L’utilisation de l’énergie nucléaire pose la question de la prise en compte des radionucléides avec l’environnement. Actuellement, leur mitigation est un enjeu majeur de la chimie associée au domaine du nucléaire. Ce travail de thèse a suivi deux axes de recherche : le piégeage des radionucléides par une famille de solides poreux Metal-Organic Frameworks (MOF) et la cristallochimie des carboxylates d’actinides tétravalents. La maitrise de cette dernière pourrait permettre de faciliter l’étude de la spéciation des actinides dans l’environnement. Un intérêt particulier a été porté sur la capture de l’iode dans des MOF à base d’aluminium, avec la mise en évidence de fonctionnalités (donneur d’électron) qui favorise son piégeage. Les capacités d’encapsulation d’actinides légers (Th et U) dans les MOF et leur stabilité sous irradiation γ ont également été investigués. Parallèlement, plus de vingt nouveaux carboxylates d’actinides tétravalents (U et Th) ont été caractérisés par DRX sur monocristal. Certains d’entre eux, préparés par hydrolyse contrôlée en condition solvothermale, sont construits à partir d’assemblages polynucléaires ([U4], [Th6], [U6] et [U38]). Afin de comprendre la formation de ces assemblages, l’étude ex-situ (DRX, EXAFS, RMN, SEM) de la synthèse du composé {U38} a été menée. / The use of nuclear energy obviously raises the question of the presence of radionuclides in the environment. Currently, their mitigation is a major issue associated with nuclear chemistry. This thesis focuses on both the trapping of radionuclides by porous solids called Metal-Organic Frameworks (MOF) and the crystal chemistry of the carboxylate of tetravalent actinides (AnIV). The academic knowledge of the reactivity of carboxylate of AnIV could help the understanding of actinides speciation in environment. We focused on the sequestration of iodine by aluminum based MOF. The functionalization (electron-donor group) of the MOF drastically enhances the iodine capture capacity. The removal of light actinides (Th and U) from aqueous solution was also investigated as well as the stability of (Al)-MOF under γ radiation. More than twenty coordination polymers based on tetravalent actinides have been synthesized and characterized by single crystal X-ray diffraction. The use of controlled hydrolysis promotes the formation of coordination polymers exhibiting polynuclear cluster ([U4], [Th6], [U6] and [U38]). In order to understand the formation of the largest cluster, the ex-situ study of the solvothermale synthesis of compound {U38} has also been investigated.

[Truncated abstract] The highly weathered, phosphorus-fixing soils of Western Australia require large amounts of P fertiliser to produce acceptable crop yields. Chickpea (Cicer arietinum L.) is an important leguminous crop that is increasingly used in rotations with wheat (Triticum aestivum L.), Western Australia’s major crop. Chickpea and a range of other species exude P-mobilising carboxylates into the rhizosphere. Plants that exude carboxylates may need less P fertiliser or may use P in the soil that is unavailable to other plants. There is a wealth of information about P mobilisation and carboxylate exudation by white lupin; in contrast, research on carboxylate exudation by chickpea is fairly limited. The major aim of this PhD research project was to investigate the relationships between exudation of carboxylates and soil and plant P status for chickpea ... In conclusion, whereas carboxylate exudation of plants such as white lupin is clearly targeted at P acquisition, chickpea showed constitutive carboxylate exudation mainly of malonate into the rhizosphere in a series of experiments, each with a different design. Unlike white lupin, chickpea forms associations with mycorrhizal fungi that may improve plant P status. Some of the functions of constitutive carboxylate exudation by chickpea may include P acquisition and deterring microorganisms, but the exact reasons and mechanisms remain unresolved.

Les matériaux traités dans ce travail de thèse sont des composés hybrides organisés, appartenant à la famille des ‘MOFs’ pour ‘Metal Organic Frameworks’, associant une composante minérale d’oxyde et/ou hydroxyde métallique et d’une partie organique, carboxylate ou dicarboxylate. Les structures cristallographiques des carboxylates métalliques aliphatiques à longues chaînes carbonées de type Zn(CnH2n-1O2)2 (n = 11, 12 et 14), Mg(C10H21O2)2(H2O)3 et Mg(C10H16O4) (H2O)2 ont été déterminées. La cristallochimie des carboxylates est plus complexe dans le cas du zinc que dans celui du magnésium à cause de la présence de polytypies et de désordre conformationnel. Une nouvelle famille de carboxylates de zinc mixtes a été étudiée avec deux chaînes carbonées de longueurs différentes. Enfin une étude par XPS de surfaces de cuivre couvertes de carboxylates montre un effet de l’orientation de la surface. Le composé [Ni3(OH)2(tp)2(H2O)4].2H2O (tp = C8H4O4) (phase A) métamagnétique subit deux déshydratations successives pour donner les phases B [Ni3(OH)2(tp)2(H2O)2] et C [Ni3(OH)2(tp)2]. Les phases B et C sont des antiferromagnétiques cantés. La structure du composé [Ni3(OH)2(O2CC4H2SCO2)2.2H2O] a été résolue ab initio à partir de données synchrotron sur poudre. Les structures magnétiques des composés M(II)2(OH)2(tp) (Fe et Mn) et de la solution solide (FexCo2-x)(OH)2(tp) ont été déterminées par diffraction des neutrons sur poudre. La spectrométrie Mössbauer du 57Fe a mis en évidence un couplage spin-orbite sur le site 2b. / The materials treated in this thesis are organized hybrid compounds belonging to the MOFs (Metal Organic Frameworks) family, associating a mineral component, a metallic oxide or hydroxide, and an organic part (a carboxylate or dicarboxylate). The crystallographic structures of the aliphatic metallic carboxylates with long chains, Zn(CnH2n-1O2)2 (n = 11, 12 and 14), Mg(C10H21O2)2(H2O)3 and Mg(C10H16O4)(H2O)2, were determined. The crystallochemistry of the carboxylates is more complex for zinc than for magnesium, due to the presence of polytypes and conformational disorder. A new family of mixed zinc carboxylates with carbon chains of various lengths was studied. The compound Ni3(OH)2(tp)2(H2O)4 (tp = C8H4O42-) (phase A) metamagnetic undergoes two successive dehydrations leading to the phases B Ni3(OH)2(tp)2(H2O)2 and C Ni3(OH)2(tp)2. The phases B and C are canted antiferromagnetic. The structure of the compound Ni3(OH)2(O2CC4H2SCO2)2(H2O)4 was resolved ab initio by XRPD. The magnetic structures of the compounds M(II)2(OH)2(tp) (Fe and Mn) and of the solid solution (FexCo2-x)(OH)2(tp) were determined by neutrons powder diffraction. The Mössbauer spectrometry of the 57Fe pointed out a spin-orbit coupling for iron atoms situated on the site 2b.