Dissertations / Theses on the topic 'Polynuclear Coordination Complexes'

This thesis documents the successful syntheses of six novel 2,2':6',2"-terpyridine-amine based polydentate ligands and a range of mono-, di-, and polynuclear complexes derived from them. The ability of some dinuclear complexes to affect the rate of hydrolysis of the phosphate diester group in the DNA model compound, bis-p-nitrophenyl phosphate (BNPP) has also been explored. Owing to the presence of two potential ligating groups in each polydentate ligand, a number of dinuclear, tetranuclear and serendipitous supramolecular architectures have been produced and characterised during this research. The polydentate ligands were synthesised by stepwise functionalisation of the progenitor ligand, 4'-(2"'-toluyl)-2,2':6',2"-terpyridine (L2.1), at its ortho methyl position via free radical bromination, and where various amine groups were appended by nucleophilic substitution reactions. The detailed ligand syntheses, and characterisation are discussed in Chapter 2, along with the crystal structures of some ligands. Chapter 3 describes coordination chemistry of 4'-(2"'-toluyl)-2,2':6',2"-terpyridine with transition metal ions. Thirteen new complexes of Ni(II), Cu(II), Zn(II) and Ag(I) are reported, where Ag(I) produced a striking spiral shaped polymer with L2.1 having unusual „hyperdentate‟ nitrogen atoms. Two polydentate ligands, 4'-[2"'-{(2-pyridylmethyl)aminomethyl}phenyl]-2,2':6',2"-terpyridine, L2.3, and 4'-[2"'-{bis(2-pyridylmethyl)aminomethyl}phenyl]-2,2':6',2"-terpyridine, L2.4, produced six different dinuclear and tetranuclear metal complexes (Chapter 4). The Zn(II) dinuclear complexes were used to study kinetics of hydrolysis of BNPP, and the enhanced rates were reported compared to the analogous mononuclear complexes. The detailed experimental methodology and results are discussed in Chapter 5. The most interesting outcome of this research was formation of the box and wheel shaped complexes, where the ligand L2.3 binds with different metal ions via different coordination modes. The box shaped tetranuclear complexes were synthesised deliberately via structural control over the coordination chemistry of terpyridine-type site of L2.3, where the coordination flexibility of the pendent picolylamine-type site of the ligand was used to bind with other metal ions. The tetranuclear [M¹₂M²₂(L2.3)₄X₂]⁶⁺ box shaped complexes were formed when two divalent M¹ ions bridge between the ligands to produce octahedral bis-terpyridine type complex M¹(L2.3)₂, and then two divalent M² ions link two M¹(L2.3)₂ units together through picolylamine binding sites, where X = Cl⁻, Br⁻, CH₃COO⁻; M¹ = Fe(II), Zn(II), Ni(II); M² = Zn(II), Cu(II). The bis-bidentate bridging ligand terephthalate was also deliberately encapsulated in the middle of Fe₂Zn₂L2.3 box to produce the complex where X₂ = terephthalate. These structures invite speculation that it may be possible to bind and react molecules within these boxes. In a more fortuitous outcome, Ni(II) ions were found to bind to both sites of L2.3 to give, exclusively, an unprecedented decanuclear wheel-shaped structure. A halide ion occupies the central position in the wheel, with Br⁻ being preferred over Cl⁻. The detailed crystal structures, and properties of the wheels shaped Ni₁₀(L2.3)₁₀ complexes are discussed in Chapter 6.

The work presented in this thesis deals with the employment of Schiff base ligands used to synthesise novel 3d-4f polynuclear coordination clusters (PCCs) and the investigation into their potential magnetic, luminescent and catalytic properties. Chapter one provides a general introduction to the chemistry described in the thesis. It includes a general overview of 3d-4f PCC chemistry and the applications of these materials and previous synthetic strategies for the preparation of Schiff base PCCs. A rationale is presented for the ligands employed in the thesis and a synthetic strategy is devised for the synthesis of specific materials. The initial chapters are focused on the synthesis of 3d-4f PCCs with novel core topologies and the study of their magnetic properties. Several novel series of 3d-4f PCCs are presented with unique core topologies which are previously unobserved in 3d-4f PCC chemistry. In addition, some of the presented PCCs display single-molecule magnet (SMM) properties or a significant magnetocaloric effect (MCE). Chapter five bridges synthetic aspects discussed in the previous chapters, with a synthetic study targeting 3d-4f PCCs with a defect dicubane core (2,3M4-1) and introduces the term “isoskeletal” to describe PCCs which possess the same topology or related organic structures with the same host framework but different guests. Chapters seven to nine are focused on the development of a well characterised isoskeletal family of 3d-4f PCCs with a defect dicubane core and the investigation of their potential catalytic properties in a range of organic reactions including Michael Addition, Friedel-Crafts alkylations and multicomponent reactions. Characterisation of the 3d-4f PCCs is emphasised and verifies the stability of the 2,3M4-1 core in solution. An attempt at understanding the catalytic system and mechanistic aspects is undertaken, which is not explored in previously reported 3d-4f PCC co-operative catalysis. Chapter ten provides an overall conclusion to the work presented in the thesis, whilst highlighting the contributions of this work to the reported literature.

Transition-metal chemistry in ionic liquids (IL) has achieved intrinsic fascination in the last few years. The use of an IL as environmental friendly solvent, offers many advantages over traditional materials synthesis methods. The change from molecular to ionic reaction media leads to new types of materials being accessible. Room-temperature IL have been found to be excellent media for stabilising transition-metal clusters in solution and to crystallise homo- and heteronuclear transition-metal complexes and clusters. Furthermore, the use of IL as solvent provides the option to replace high-temperature routes, such as crystallisation from the melt or gas-phase deposition, by convenient room- or low-temperature syntheses. Inorganic IL composed of alkali metal cations and polynuclear transition-metal cluster anions are also known. Each of these areas will be discussed briefly in this contribution
Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich

Transition-metal chemistry in ionic liquids (IL) has achieved intrinsic fascination in the last few years. The use of an IL as environmental friendly solvent, offers many advantages over traditional materials synthesis methods. The change from molecular to ionic reaction media leads to new types of materials being accessible. Room-temperature IL have been found to be excellent media for stabilising transition-metal clusters in solution and to crystallise homo- and heteronuclear transition-metal complexes and clusters. Furthermore, the use of IL as solvent provides the option to replace high-temperature routes, such as crystallisation from the melt or gas-phase deposition, by convenient room- or low-temperature syntheses. Inorganic IL composed of alkali metal cations and polynuclear transition-metal cluster anions are also known. Each of these areas will be discussed briefly in this contribution.
Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

L’objectif consistant à élaborer des «aimants par conception» peut être atteint en adaptant les structures moléculaires des complexes de coordination. Les molécules conçues devraient présenter les caractéristiques requises pour des applications spécifiques, qui résultent de leur riche diversité structurale. Des complexes mononucléaires à base de Ni avec une grande anisotropie magnétique et des molécules polynucléaires à base de Ni et de Co sont préparés et étudiés dans cette thèse. Les synthèses, les études magnétiques et les propriétés électrochimiques des complexes contenant un ligand pontant non innocent sont étudiées. Les complexes mononucléaires Ni(II) à géométrie bipyramide trigonale sont préparés avec des ligands axiaux et les contre-anions différents. L'effet de la nature des ligands axiaux et du changement structural induit par les contre-anions sur l'anisotropie magnétique est étudié expérimentalement et analysé à l'aide de calculs théoriques. Des molécules organiques sont utilisées pour concevoir des complexes trinucléaires à grande anisotropie magnétique et à couplage d'échange faible. Plusieurs complexes polynucléaires à base de Ni et de Co où le TTC³⁻ agit comme un ligand pontant innocent et le HHTP³⁻ comme un ligand non innocent typique sont cristallisés avec diverses structures (TTC = Trithiocyanurate; HHTP = Hexahydroxytriphénylène). Pour les complexes contenant le ligand non innocent (HHTP), les anions radicalaires sont produits par électrochimie. La combinaison de la spectro-électrochimie et de la spectroscopie à résonance paramagnétique électronique couplée à des études d'électrochimie permet d'étudier la délocalisation des électrons sur les radicaux organiques générés et le couplage d'échange entre les ions métalliques
The objective of elaborating “magnets by design” can be achieved by tailoring the molecular structures of coordination complexes. The designed molecules are expected to exhibit the characteristics required for specific applications, virtually resulting from their rich structural diversity. Mononuclear Ni-based complexes with large magnetic anisotropy and polynuclear Ni- and Co-based molecules are designed in this dissertation. The syntheses, magnetic studies, and electrochemical properties of the complexes containing non-innocent bridge ligand are investigated. The Ni(II) mononuclear complexes with trigonal bipyramid geometry are prepared by tuning the axial ligands and the counter anions. The effect of the nature of the axial ligands and the structural change induces by the counter anions on magnetic anisotropy is studied experimentally and analyzed with the help of theoretical calculations. Large organic molecules are used to design trinuclear complexes with large magnetic anisotropy and weak exchange coupling. Several polynuclear Ni- and Co-based complexes with TTC³⁻ acting as an innocent bridging ligand and HHTP as a typical non-innocent ligand, are crystallized with various structures (TTC = Trithiocyanurate; HHTP = Hexahydroxytriphenylene). For the complexes containing the non-innocent ligand (HHTP), radical anions are produced by electrochemistry. The combination of spectroelectrochemical and Electron Paramagnetic Spectroscopy coupled to electrochemistry studies allow investigating the delocalization of the electrons on the generated organic radicals and the exchange coupling among the metal ions

Les polymères de coordination poreux appelés Metal Organic Frameworks (MOF) sont envisagés pour des développements et applications prometteuses dans la catalyse par exemple. La compréhension des mécanismes de synthèse et leurs croissances cristallines restent cependant un défi. Actuellement, seules quelques études in-situ ont été réalisées pour rationnaliser la synthèse des MOFs, comme des suivis par résonance magnétique nucléaire, par spectroscopie de masse ou par diffraction des rayons X en dispersion d'énergie. Nous proposons, l'analyse thermodifférentielle qui est une technique plus aisée à mettre en oeuvre et permet un suivi calorimétrique en continu pour identifier les phénomènes thermiques régissant la synthèse tels que la réaction de formation et la cristallisation. Grâce à ces analyses thermiques, le domaine réactionnel est déterminé et l'importance des différents paramètres influençant la synthèse sont étudiés, comme la température et les vitesses de chauffage et de refroidissement ainsi que la concentration des réactifs. Ce suivi calorimétrique a été appliqué à la synthèse de nouveaux composés de coordination poreux à base d'un dérivé tetra acide carboxylique de la porphyrine pour en comprendre les étapes réactionnelles importantes. La détermination des structures cristallines montre que certains appartiennent à la classe des Porphyrin Paddle-Wheel Frameworks. De nouvelles approches pour la synthèse de MOFs sont également proposées, en utilisant des ligands organiques acides, imines, oximes et bases de Schiff
Porous coordination polymers so called Metal Organic Frameworks (MOFs) are considered for promising development and applications such as in catalyst. However, the understanding of the synthesis mechanisms and crystal growth is a challenge. Currently, only a few in-situ studies have been done to rationalize the synthesis of MOFs, such as monitoring by nuclear magnetic resonance, mass spectroscopy and energy dispersive X-ray diffraction. In this manuscript the differential scanning calorimetry is proposed as an easier technique to implement that allows a continuous calorimeter tracking to identify the phenomena which govern the synthesis such as the formation reaction and crystallization temperatures. With such thermal analyses, the temperature range of the reaction was determined and the importance of various parameters influencing the synthesis was studied, such as heating temperatures and cooling speeds or reactant concentration. This was applied to the synthesis of new porous coordination compounds based on porphyrin acid derivative in order to understand the important reaction steps. Crystal structure determinations show that some are Porphyrin Paddle-Wheel Frameworks. New approaches to the MOFs synthesis are also proposed using organic ligands like acids, imines, oximes and Schiff bases

Utilisation du ligand tripode ch(pph::(2))::(3) pour synthetiser des complexes mononucleaires (rh(i), ir(i) et mo(0)), homobinucleaires (rh(i)-rh(i)), heterobinuclaires (rh(i)-cu(i), rh(i)-au(i), ir(i)-au(i) et polynucleaires (rh(i)::(4), rh(i)-cu(i)::(2)). Etude des proprietes catalytiques en hydrogenation des olefines et acetylene

Les molécules-aimants, ou Single-Molecule Magnets en anglais, sont des complexes polymétalliques qui possèdent la propriété remarquable de se comporter individuellement comme des aimants. Synthétisées selon les méthodes de la chimie de coordination elles sont devenues l'objet d'une intense activité de recherche multidisciplinaire à l'interface de la chimie et de la physique. C'est dans ce contexte que se situe notre travail de thèse qui nous a conduit à synthétiser plusieurs séries de complexes polynucléaires nouveaux puis a les caractériser cristallographiquement et étudier leurs propriétés magnétiques dont les résultats sont présentés dans ce mémoire. Le premier chapitre présente l'approche théorique, expérimentale et les avancées scientifiques principales dans le domaine des molécules-aimants. Le deuxième chapitre concerne quatre séries de composés obtenus avec des ligands de type oxime. Deux de ces composés [Mn3]n et [Mn6] sont des complexes homonucléaires à base de manganèse et les deux autres [Ln2Cu2] et [Ln3Cu8] (LnIII = Dy, Gd, Tb, Y) des complexes hétéronucléaires CuII - LnIII. D'après les études magnétiques nous avons constaté que [Mn3]n, [Dy2Cu2] et [Dy3Cu8] se comportent comme des molécules-aimants mais que [Mn6] ne manifeste pas les propriétés d'une molécule-aimant. Le troisième chapitre concerne un composé tetranucléaire [Mn4] et une série de complexes dodecanucléaires [Ln4Cu8] (LnIII = Dy, Gd, Tb, Y) obtenus avec des ligands de type benzoxazoles. Les études des propriétés magnétiques ont mis en évidence le couplage antiferromagnétique des ions Mn dans le cubane [Mn4]. Pour la série [Ln4Cu8] (LnIII = Dy, Gd, Tb, Y) sur la base du complexe d'yttrium le couplage Cu-Cu a été négligé et pour le complexe [Gd4Cu8] nous avons mis en évidence des interactions Cu-Gd ferromagnétiques et Gd-Gd antiferromagnétiques. Les mesures faites sur le composé [Dy4Cu8] ont mis en évidence le comportement caractéristique d'une molécule-aimant. Le dernier chapitre présente les résultats obtenues pour un complexe tetradécanucléaire à valence mixte MnII - MnIII [Mn14] que nous avons obtenu a partir d'un ligand de type base de Schiff et dans lequel coexistent des interactions antiferromagnétiques et ferromagnétiques entre les ions manganèse avec un zero-field splitting important. La conclusion générale fait le bilan de nos résultats et donne quelques perspectives ouvertes par notre travail.

碩士
中原大學
化學研究所
103
This thesis discusses the structures and properties of polynuclear copper(I) complexes and coordination polymers supported by formamidine and formamidinate ligands. One-pot solvothermal reactions of 3-aminopyridine, 4-chloroaniline, 4-bromoaniline, 4-iodoaniline, or 4-amino-2-chloropyridine with triethylorthoformate and CuX (X = Cl–, Br– , I–) afforded complexes [Cu3(3-pyf)2Cl3]n, 1, [Cu4(3-pyf)4Br4], 2, [Cu(3-pyf)I]n, 3, [Cu2(4-cphf)2], 7, [Cu(4-Hbphf)4Br2], 8 , [Cu2(4-iphf)2], 10 and [Cu2(2-cpf)2], 11, whereas the reactions of CuX (X = Cl–, Br–) with 3-aminopyridine and 4-bromoaniline, in a Methanol (MeOH) or tetrahydrofuran (THF) or acetonitrile (ACN) solution containing triethylorthoformate and sodium hydroxide gave complexes [Cu4(3-pyf)4], 4, {[Cu8(3-pyf)8]·5THF}, 5, [Cu(3-pyf)]n, 6, and[Cu2(4-bphf)2], 9, which were characterized by X-ray crystallography. Complex 1 is a 3D coordination polymer with (62.82.102)(62.8)2 - sur; bbf-3,4-Ccm topology, complex 2 is a very rare example of tetranuclear paddlewheel complex containing rhombohedral Cu2X2, complex 3 is a 1D chain structure, complex 4 is a tetranuclear complex with cuprophilicity, complex 5 is the first octanuclear complex with Cu(I)---Cu(I) interactions, complex 6 is a 2D structure of {44.62} topology, complexes 7, 9–11 are dinuclear copper(I) complexes that shows different distances of Cu(I)---Cu(I), and complex 8 is a dinuclear complex containing rhombohedral Cu2Br2 unit.

Yes
A highly porous carbon was synthesized using a coordination complex as an unusual precursor. During controlled pyrolysis, a trinuclear copper complex, [CuII3Cl4(H2L)2]·CH3OH, undergoes phase changes with melt and expulsion of different gases to produce a unique morphology of copper-doped carbon which, upon acid treatment, produces highly porous graphitic carbon with a surface area of 857 m2 g–1 and a gravimetric hydrogen uptake of 1.1 wt % at 0.5 bar pressure at 77 K.
EPSRC (EP/R01650X/1 for VPT, and EP/E040071/1 for MT) and the University of Bristol

Η σύνθεση και ο χαρακτηρισμός πλειάδων των μετάλλων μετάπτωσης σε ενδιάμεσες οξειδωτικές βαθμίδες αποτελεί σήμερα έναν από τους κύριους ερευνητικούς στόχους πολλών επιστημονικών ομάδων παγκοσμίως εξαιτίας των εφαρμογών που βρίσκουν σε διάφορα επιστημονικά πεδία, όπως στη βιοανόργανη χημεία, στην επιστήμη των υλικών, στη μοριακή φυσική και στη θεωρητική χημεία. Οι πλειάδες αυτές περιέχουν πολλές φορές έναν ασυνήθιστα μεγάλο αριθμό ασυζεύκτων ηλεκτρονίων στη θεμελιώδη κατάσταση και παρουσιάζουν εξαιρετικό ενδιαφέρον από μαγνητικής απόψεως. Αυτό συμβαίνει γιατί μια υψηλή τιμή spin στη θεμελιώδη κατάσταση είναι αναγκαία (άλλα όχι ικανή) συνθήκη ώστε αυτού του είδους οι σύμπλοκες ενώσεις να εμφανίζουν το φαινόμενο του μονομοριακού μαγνητισμού (single-molecule magnetism). Στην παρούσα Εργασία μελετήθηκε το σύστημα αντίδρασης μαγγάνιο/α-βενζοΐνη οξίμη (α-benzoin oxime, bzoxH2) κάτω από βασικές συνθήκες, το οποίο οδήγησε στην απομόνωση και το δομικό (μέσω κρυσταλλογραφίας ακτίνων-Χ σε μονοκρυστάλλους) και μαγνητοχημικό χαρακτηρισμό των μοριακών πλειάδων [Mn8O4(bzox)8(MeOH)4] (1), [Mn9O2(bzox)11(bzoxH)(MeOH)4(H2O)2] (2) και [Mn9O2(bzox)11(bzoxH)(H2O)6] (3). Τα σύμπλοκα 1-3 αποτελούν τις πρώτες δομικά χαρακτηρισμένες πλειάδες τρισθενών μεταλλοϊόντων με υποκαταστάτη την α-βενζοΐνη οξίμη. Το σύμπλοκο 1 αποτελείται από οκτώ ιόντα MnIII, με το δομικό του πυρήνα να παρουσιάζει μία πρωτότυπη τοπολογική διευθέτηση τεσσάρων τριγωνικών Mn3 υπομονάδων, ανά δύο κάθετων μεταξύ τους, η οποία οδηγεί σε μια ενδιάμεση τιμή spin στη θεμελιώδη κατάσταση, SΤ = 2. Τα ισοδομικά σύμπλοκα 2 και 3 αποτελούνται από εννέα ιόντα MnIII, με το δομικό τους πυρήνα να παρουσιάζει μία επίσης πρωτότυπη τοπολογική διευθέτηση εναλλασσσόμενων τριγωνικών και γραμμικών Mn3 υπομονάδων, η οποία οδηγεί σε μια ενδιάμεση τιμή spin στη θεμελιώδη κατάσταση, SΤ = 3.
The synthesis and characterization of polynuclear metal complexes (clusters) containing paramagnetic 3d-metal ions in intermediate oxidation states have gained intense interest due to the applications of these compounds in several fields of science, such as bioinorganic chemistry, materials science, molecular physics and theoretical chemistry. Such high nuclearity transition metal clusters are one of the growing research subjects in Molecular Magnetism, given the fact that they often possess a fairly large ground-state spin value, which is one of the necessary requirements for a molecule to be able to exhibit the phenomenon of single-molecule magnetism. In the present work, we studied the reaction scheme manganese/α-benzoin oxime (bzoxH2) under basic conditions, which has led to the isolation, and structural (through single-crystal X-ray crystallography) and magnetochemical characterization of the molecular complexes [Mn8O4(bzox)8(MeOH)4] (1), [Mn9O2(bzox)11(bzoxH)(MeOH)4(H2O)2] (2) and [Mn9O2(bzox)11(bzoxH)(H2O)6] (3). Complexes 1-3 are the first structurally characterized trivalent metal clusters with the ligand α-benzoin oxime. Compound 1 consists of eight MnIII atoms and its irregular metal core presents an unprecedented topology based on four triangular Mn3 units, which are vertical to each other, thus leading to an ST = 2 ground state. The isostructural compounds 2 and 3 comprise nine MnIII atoms arranged in a unusual topology based on linear and triangular Mn3 units, thus leading to an ST = 3 ground state.