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Tilford, Claire. « Experimental investigations of the electronic interactions within multinuclear first row transition metal complexes ». Thesis, University of East Anglia, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302144.
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Chilton, Nicholas Frederick. « Magnetic anisotropy of transition metal complexes ». Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/magnetic-anisotropy-of-transition-metal-complexes(64b34057-8a7a-44db-a89a-22a233fdefb5).html.
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The study of magnetic anisotropy in molecular systems permeates the physical sciences and finds application in areas as diverse as biomedical imaging and quantum information processing. The ability to understand and subsequently to design improved agents requires a detailed knowledge of their fundamental operation. This work outlines the background theory of the electronic structure of magnetic molecules and provides examples, for elements across the Periodic Table, of how it may be employed to aid in the understanding of magnetically anisotropic molecules. The magnetic anisotropies of a series of dimetallic NiII2 complexes and a RuIII2MnII triangle are determined through multi-frequency Electron Paramagnetic Resonance (EPR) spectroscopy and ab initio calculations. The magnetic anisotropy of the former is found to be on the same order of magnitude as the isotropic exchange interactions, while that of the latter is found to be caused by large antisymmetric exchange interactions involving the RuIII ions. An intuitive electrostatic strategy for the prediction of the magnetic anisotropy of DyIII complexes is presented, allowing facile determination of magnetic anisotropy for low symmetry molecules. Through the presentation of the first near-linear pseudo-two-coordinate 4f-block complex, a new family of DyIII complexes with unprecedented Single Molecule Magnet (SMM) properties is proposed. Design criteria for such species are elucidated and show that in general any two-coordinate complex of DyIII is an attractive synthetic target. The exchange interaction between two DyIII ions is directly measured with multi-frequency EPR spectroscopy, explaining the quenching of the slow magnetic relaxation in the pure species compared to the SMM properties of the diluted form. The interpretation of this complex system was achieved with supporting ab initio calculations.
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Avalos, Ovando Oscar Rodrigo. « Magnetic Interactions in Transition Metal Dichalcogenides ». Ohio University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1540818398439166.
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Johnson, Donald Martin. « Cyanoscorpionates and Transition Metal Complexes ». Digital Commons @ East Tennessee State University, 2010. https://dc.etsu.edu/etd/1725.
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The new dihydrobis(4-cyano-3-tert-butylpyrazolylborate) ligand has been synthesized. Isolated crystals of the thallium complex were collected and structurally characterized by X-ray diffraction. Transition metal complexes of the ligand are currently under investigation.
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Ajulu, Florence Adhiambo. « Interaction of phosphirenes and phosphinidenes with transition metal complexes ». Thesis, University of Sussex, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358452.
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Jassim, Ishmaeel Khalil. « Magnetic and lattice interaction in 3D transition metal compounds ». Thesis, Loughborough University, 1990. https://dspace.lboro.ac.uk/2134/31919.
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The importance and nature of magnetic and lattice degrees of freedom and their interaction in transition metal magnets has been investigated. Two different alloy systems in which the magnetic 3D electrons either had localised or itinerant characteristics were chosen. As an example of localised behaviour, Heusler alloys in which the magnetic moment was confined to Mn atoms were chosen, e.g. Pd2MnIn. The manganese atoms are separated by more than 4.6Å. These materials provide a good approximation to a Heisenberg system, having long-range interactions.
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Saureu, Artesona Sergi. « From mononuclear to dinuclear : magnetic properties of transition metal complexes ». Doctoral thesis, Universitat Rovira i Virgili, 2016. http://hdl.handle.net/10803/386451.
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En les darreres dècades, el món de la tecnologia i el desenvolupament de nous aparells electrònics s'han convertit en vitals per la nostra societat. Considerant la creixent demanda per la interpretació de resultats experimentals, la millora dels mètodes teòrics i el creixement dels recursos computacionals ens han permés un millor enteniment del comportament magnètic en sistemes amb metalls de transició. L'objectiu d'aquesta tesi és contribuir en aquest camp d'investigació amb l'estudi de materials magnètics utilitzant eines computacionals (DFT, TD-DFT, CASSCF, CASPT2, DDCI, etc.), i en alguns casos, combinant-ho amb resultats experimentals. La primera part (Capítols 3 i 4) inclou l'estudi dels estats electronics de complexes de spin-crossover de Fe(II) i Fe(III) combinant la teoria funcional de la densitat (DFT i TD-DFT) amb mètodes multiconfiguracionals (CASSCF, CASPT2). A més a més, utilitzant la mateixa combinació, hem descrit el fenomen LIESST en complexes de Fe(III). La segona part (Cap. 5 i 6) exposa l'estudi de les propietats magnètiques associades a l'acoblament magnètic utilitzant mètodes variacionals (DDCI, DDCI-2), en un complex de Fe(IV) i un complex bimetàl·lic [MnCr]-oxalat, y com els canvis estructurals afecten a aquest acoblament. Altrament, hem fet un rigurós anàlisi de l'estructura electrònica del complex de Fe(IV) per proporcionar més informació en la descripció més adequada del sistema.En las últimas décadas, el mundo de la tecnologia y el desarrollo de nuevos aparatos electrónicos se han convertido en vitales para nuestra sociedad. Considerando la creciente demanda para la interpretación de resultados experimentales, la mejora de los métodos teóricos y el crecimiento de los recursos computacionales nos han permitido un mejor entendimiento de los comportamientos magnéticos en los sistemas con metales de transición. El objetivo de esta tesis es contribuir a este campo de investigación con el estudio de materiales magnéticos usando herramientas computacionales (DFT, TD-DFT, CASSCF, CASPT2, DDCI, etc.), y en algunos casos, combinando con resultados experimentales. La primera parte (Capítulo 3 y 4) incluye el estudio de los estados electrónicos de los complejos de spin-crossover de Fe(II) y Fe(III) combinando la teoria funcional de la densidad (DFT y TD-DFT) con métodos multiconfiguracionales (CASSCF, CASPT2). Además, usando la misma combinación, hemos descrito el fenómeno LIESST en complejos de Fe(III). La segunda parte (Cap. 5 y 6) expone el estudio de las propiedades magnéticas asociadas al acoplamiento magnético utilizando metodos variacionales (DDCI, DDCI-2), en un complejo de Fe(IV) y un complejo bimetálico [MnCr]-oxalato, y como los cambios estructurales afectan a ese acoplamiento. Por otra parte, hemos hecho un riguroso analisis de la estructura electrónica del complejo de Fe(IV) para aportar la información para la descripción mas adecuada del sistema.
Over the last decades the world of technology and the development of new devices have become vital for our society. Considering the growing demand for interpretation of experimental observations, the improvement of theoretical methods and the increasing of the computational resources has allowed us to deepen the understanding of magnetic beahvior of metal transitions architectures. The aim of this thesis is to contribute to this research field with the study of magnetic materials by using computational tools (DFT, TD-DFT, CASSCF, CASPT2, DDCI, etc.), and in some cases combining it with experimental results. The first part (Chapters 3 and 4) includes the study of the electronic states of Fe(II) and Fe(III) spin-crossover complexes combining the density functional theory (DFT and TD-DFT) with multiconfigurational methodologies (CASSCF, CASPT2). In addition, we have described the LIESST phenomenon in Fe(III) using the same combination. The second part (Chapters 5 and 6) exposes the study of the magnetic properties related to the magnetic coupling using variational methods (DDCI, DDCI-2) of a Fe(IV) complex and bimetallic [MnCr] oxalate-based complexes and how changes can influence to the coupling. Moreover, a rigorous analysis of the electronic structure of the Fe(IV) system has been performed to provide more information about the most adequate description of the system in terms of intuitive chemical concepts.
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Wood, D. « Magnetic and spectroscopic studies of transition metal complexes of water soluble porphyrius ». Thesis, Imperial College London, 1985. http://hdl.handle.net/10044/1/37901.
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Xia, Shihua. « Synthesis, characterization and magnetic properties of some transition metal diorganophosphinate and dimethylarsinate complexes ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq25190.pdf.
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Tabookht, Zahra. « Theoretical study of magnetic and conducting properties of transition metal nanowires ». Doctoral thesis, Universitat Rovira i Virgili, 2011. http://hdl.handle.net/10803/52798.
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En la presente tesis doctoral se ha realizado un estudio computacional de las propiedades electrónicas de sistemas basados en cadenas metálicas monodimensionales de la familia de los llamados nanowires, concretamente su magnetismo y conductividad. Estas cadenas lineales se sustentan gracias a los ligandos orgánicos que se organizan a su alrededor, cuyo número de sitios de unión determina la nuclearidad de la cadena. Para estas moléculas, llamadas cadenas metálicas extendidas, se han calculado los parámetros de acoplamiento magnético con el método CASPT2. El uso del Hamiltoniano de Heisenberg estándar para los sistemas M3(dpa)4Cl2 cuando hay dos electrones no desapareados en cada centro, ha sido examinado mediante el cálculo del valor de λ mediante cálculos DFT. Las diferentes conductividades eléctricas observadas en las cadenas MMX [Ni2(dta)4I]∞ y [Pt2(dta)4I]∞ (dta = CH3CS2) y sus estados de ordenación de carga han sido analizados con parámetros de estructura electrónica extraídos a partir de cálculos DFT periódicos y de correlación combinados con la teoría del Hamiltoniano efectivo.In the present thesis, magnetic and conducting properties of systems, one-dimensional chains of the family of so-called nanowires, have been studied computationally. These linear chains are supported by organic ligands surrounding the metal backbone where the number of binding sites determines the nuclearity of the chain. For these molecules, also called extended metal atom chains, magnetic coupling parameters have been calculated with the CASPT2 method. The use of standard Heisenberg Hamiltonian for systems M3(dpa)4Cl2 when two unpaired electrons are localized on each magnetic center has been examined by calculating the value of λ from DFT calculations. The different electrical conductivities observed in MMX chains [Ni2(dta)4I]∞ and [Pt2(dta)4I]∞ (dta = CH3CS2) and the charge ordering state have been analyzed with DFT periodic calculations and also through the comparison of extracted electronic structure parameters from ab initio calculations combined with the effective Hamiltonian theory.
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Brodkorb, André. « A study of optically pure transition metal complexes and their interaction with DNA ». Doctoral thesis, Universite Libre de Bruxelles, 2001. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/211622.
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Martin, Claudia. « Density functional study of the electronic and magnetic properties of selected transition metal complexes ». Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2014. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-134958.
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Die vorliegende Promotionsarbeit “Density functional study of the electronic and magnetic properties of selected transition metal complexes” beschäftigt sich mit dem Zusammenhang zwischen strukturellen Merkmalen sowie elektronischen und magnetischen Eigenschaften von Einzelmolekül-Magneten. Im Wesentlichen konnte dabei gezeigt werden, dass die magnetischen Eigenschaften sowohl von strukturellen Merkmalen als auch von den elektronischen Eigenschaften bestimmt werden. Des Weiteren ergab sich, dass verschiedene Kenngrößen der magnetischen Eigenschaften (im speziellen der magnetische Grundzustand S sowie die magnetische Anisotropie D) miteinander korreliert sind. Dies ist im Besonderen für eine mögliche Anwendung von Einzelmolekül-Magneten im Bereich der Datenspeicherung von Bedeutung.
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Woodruff, Daniel. « Organometallic and metal-amide precursors for transition metal and lanthanide cluster complexes with interesting electronic an magnetic properties ». Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/organometallic-and-metalamide-precursors-for-transition-metal-and-lanthanide-cluster-complexes-with-interesting-electronic-an-magnetic-properties(d35cea40-6e84-4d19-ba6a-7a7fe1e4a135).html.
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This project exploited the Brönsted basicity of the organometallic/metal-amide compounds,MnCp2 and Ln[N(SiMe3)2]3·LiCl(THF)3 (Ln = Gd, Tb and Dy) in attempts to synthesizepolymetallic cluster compounds via deprotonation of X-H (X = N or S) bond containing proligands.The chemical, electronic and magnetic properties of the resulting compounds werestudied with a variety of methods.The reaction of Ln[N(SiMe3)2]3·LiCl(THF)3 (Ln = Gd, Tb and Dy) with EtSH yieldsa series of [{Ln(N(SiMe3)2)(μ2-SEt)2}4(μ3-SEt)][Li(THF)4] “Ln4” squares in which theterbium and dysprosium analogues show SMM behaviour in zero field, with the dysprosiumanalogue displaying a fast relaxation process which can be “switched off” by the applicationof a 2000 Oe external field.Reactions of MnCp2 with Me3SiNP(NHR)3 (R = nPr, Cy, tBu) afforded a series ofcompounds; [CpMn{Me3SiN=P(NHnPr)2(μ-NnPr)}]2, [Mn{Me3SiN=P(NHCy)2(NCy)}2]and [CpMn{Me3SiN=P(NHtBu)2(NtBu)}]. Q-band EPR studies of these complexes revealthat altering the R group attached to the ligand causes a variation in coordination geometryaround the manganese centers and as such alters the electronic properties of the manganesecentres present in each complex.In order to avoid the synthesis of potentially unstable organometallic/metal-amideprecursors, one pot synthetic methodologies were developed to allow the isolation a series ofμ8-oxo centred Li7M cubes [MLi7(μ8-O)(μ-hpp)6]+ (M = Co, Mn and Zn). Addition ofstiochiometric amounts of water to the initial reaction mixture produced the Li7M cubes inhigh yields.Extension of the one pot synthetic strategy to the use of DyCl3 and YbCl3 inreactions with Li-TMP (TMP = 2,2,6,6-tetramethylpipiridine) afforded the lanthanidedimers [Ln(TMP)2(μ-OEt)]2 (Ln = Dy and Yb) in which the EtO- ligands were formed via insitu ether cleavage and the dysprosium analogue shows SMM behaviour under a 7000Oeapplied field.
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Oldham, Warren James. « Synthesis and NMR properties of dihydrogen-hydride complexes of rhodium and iridium / ». Thesis, Connect to this title online ; UW restricted, 1996. http://hdl.handle.net/1773/8505.
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Wong, Chun-yuen. « Ruthenium-carbon bonding interaction synthesis and spectroscopic studies of ruthenium-acetylide, -carbene, -vinylidene and -allenylidene complexes ». Click to view the E-thesis via HKUTO, 2004. http://sunzi.lib.hku.hk/hkuto/record/B31040858.
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Liu, Mingde. « Magnetization-steps spectroscopy in dilute magnetic semiconductors and in molecular magnetism / ». Thesis, Connect to Dissertations & ; Theses @ Tufts University, 1998.
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Thesis (Ph.D.)--Tufts University, 1998 .Adviser: Yaacov Shapira. Submitted to the Dept. of Physics. Includes bibliographical references. Access restricted to members of the Tufts University community. Also available via the World Wide Web;
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Papadopoulos, Konstantinos. « Investigation of magnetic order in nickel-5d transition metal systems ». Thesis, Uppsala universitet, Molekyl- och kondenserade materiens fysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-383009.
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Double perovskite materials exhibit alterations in magnetic order through manipulation oftheir crystal structure. Certain ultra thin metallic bilayers can create an exotic magnetic stateof confined spin textures called skyrmions. In both cases, new atomic arrangements leadto new electrical and magnetic properties. The following work comprises two studies, bothof which examine the magnetic properties of transition metals in either powder or thin filmsamples. The first part is dedicated to a series of muon spin rotation and relaxation (muSR)experiments on a LaSrNiReO6, double perovskite, powder sample. In the muSR technique, aspin polarized muon beam is focused onto a powder envelope in low pressure and temperatureconditions. The spins of the implanted muons evolve depending on the intrinsic or externallyapplied magnetic field according to Larmor precession. The measurement is based onthe detection of decay positrons that carry this precession information on their preferreddecay directions. Measurements that were realized in wTF, ZF and LF setups, reveal asecond transition to magnetic order at Tc ≃ 22K, below a transition that was observed at T =261K from magnetic susceptibility measurements. The experimental results point to threemagnetic phases, paramagnetic for T > 261K, dilute ferrimagnetic for 22 < T < 261K and amagnetically ordered state for T < 22K, that may implicate ferro- and antiferromagnetismfrom Ni sublattices and Ni-Re interactions. The second part follows an attempt to produce and characterize ultra thin bilayer filmsfor the observation of interfacial chiral structures and skyrmions. Co/Fe/MgO (100) andW/Ni/Cu (100) bilayers were grown with magnetron sputter deposition in various layerthicknesses and their structure was determined by X-ray reflectometry (XRR). The XRRscans presented a relatively thick-layered Co/Fe/MgO film, while extremely thin and roughW/Ni/Cu bilayers, for the purposes of studying films with broken interfacial inversionsymmetry. This study was concluded with indicative magneto-transport measurements thatalso point to the reconfiguration of the growth procedure.
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Wong, Chun-yuen, et 黃駿弦. « Ruthenium-carbon bonding interaction synthesis and spectroscopic studies of ruthenium-acetylide, -carbene, -vinylidene and -allenylidene complexes ». Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B31040858.
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Stradiotto, Mark J. « The molecular dynamics and reactivity of transition metal and main group [íta]1-indenyl complexes / ». *McMaster only, 1999.
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Olsen, Matthew Daniel. « The synthesis and dynamic nuclear magnetic resonance studies of fluxional transition metal complexes of pyridyl based ligands ». Thesis, University of Exeter, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.363355.
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Zhang, Yixin. « Design and Synthesis of a Series of Redox Active Tetrazine and Triazine Based Transition Metal Complexes ». Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/37233.
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The use of two different chelating redox active ligands, 2,6-bis(6-methyl-1,2,4,5-3-yl) pyridine (BTZP) and 2,6-bis-(5,6-dialkyl-1,2,4-triazin-3-yl)-pyridine (BTP) in heterometallic first row and second row transition metal chemistry has yielded two new families of redox active metal complexes. These complexes were found to exhibit interesting electrochemical and magnetic properties.
In this thesis, Chapter 1 lays the foundation for the research presented within. This section covers the fundamentals of the ligand design, ligand synthesis and related coordination chemistry literature review. Chapters 2 and 3 report the results of the current thesis. In Chapter 2, the synthesis and characterization of a family of discrete molecules and supramolecular arrangements, employing the ligand BTZP, is presented. All of the complexes presented in Chapter 2 are successfully synthesized and characterized with electrochemical and magnetic studies. According to the electrochemical data, it is found that the classic “terpy-like” complexes with [Co(BTZP) 2]2+ formula fosters more stability in the redox process. In Chapter 3, a family of transition metal complexes with [M(BTP) 2]2+ (M=Fe or Co) inorganic cores were obtained through the employment of the ligand BTP with various anions. In addition, dimeric molecules with [CoX4(BTP)2] formula were also obtained by solvothermal synthesis. The complexes were also electrochemically characterized, with all the complexes capable of being reduced, while only [CoII(BTP)2] (ClO4)2 showed reversible redox process. Similar with BTZP, the series of BTP based complexes are also characterized through magnetic measurement. Only cobalt-based BTP complexes are paramagnetic, with [CoII(BTP)2]2+ being spin crossover active when BF4- and ClO4- are present. However, the presence of NCS- and halides lead to either antiferromagnetic interactions and ferromagnetic interactions dominating at different temperature regimes.
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Famengo, Alessia. « Dithiolene and thiolate transition metal complexes : towards an exploration of their multi-functional properties ». Doctoral thesis, Università degli studi di Padova, 2011. http://hdl.handle.net/11577/3423332.
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This work has dealt with the synthesis and characterization of transition metal complexes with two types of sulphur based ligands: 1,2 dithiolato ligands and thiol-carboxylate ligands.
The electronic features related to the metal-sulphur interaction, such as the rich redox behaviour associated to the interplay between the sulphur and a redox active metal, the better overlap between sulphur and metal orbitals, the ability of forming coordination compounds in different topologies, from discrete complexes to extended 1-D network, make sulphur-based coordination compounds. We have explored these features starting from non redox innocent metal bis-dithiolene complexes as possible molecular precursors in the field of molecular magnetism, as paramagnetic centers able to organize in more complex coordination compounds.
In the first part of this work, “classical” metal bis-dithiolene complexes have been investigated as metallo-ligands towards the coordination of “acceptor” metal complexes, in order to build up coordination compounds of higher nuclearities with paramagnetic centers. Particularly, the investigated dithiolenes were [Cu(mnt)2]2- ,[Cu(tfadt)2]2-and [Ni(dmid)2].- while the “acceptor” metal complexes are Mn(III) porphinato ,Mn(III) salen-like complexes and finally a mixed valence Mn(II)Mn(III) complex.
We have observed that the reactivity in solution of metal-bis –dithiolene together with the Mn-based complexes employed has lead to co-crystallization salts where the coordinating group of the dithiolene does not coordinate the Mn center.
From these observation, we have decided to synthesize a series of new 1,2 dithiolato ligands bearing a potential coordinating functional group. We have choosen to functionalize them with crown-ether macrocycles with different sizes, in order modulate their selectivity for transition metal ions or lanthanide ions. The corresponding radical nickel(dithiolene) complexes have been synthesized and polymetallic Ni-Na and Ni-Ni chains have been obtained as well as a bimetallic Ni-Ni discrete complex. We have provided their physico-chemical characterizations in order to understand their rich redox behaviour and their magnetic properties. The investigation on these new 1,2 dithiolato ligands is still in progress in order to build up polymetallic assemblies also with lanthanide ions.
We have then switched to another class of sulphur-based ligands, the thiol-carboxylate ligands. 2-mercaptonicotinic acid has been considered as versatile ligand towards the synthesis of sulphur-based metal complexes. This polyfunctional ligand can coordinate with N, O or S donor atoms. Under hydrothermal conditions, Zn(II) and 2-mercaptonicotinic acid afforded a coordination polymer where 2-mercaptonicotinic acid is S,O chelating. The electronic properties were studied by means of theoretical calculations and experimental measurments.
Under the same reaction conditions, Ni(II) did not led to any crystalline material. By switching the reaction conditions, it has been observed a mononuclear S,O chelated Ni bis(mercaptonicotinate).Questo lavoro di dottorato ha riguardato la sintesi e la caratterizzazione di complessi di metalli di transizione con leganti donatori allo zolfo. In particolare sono stati considerati i leganti 1,2 ditiolato e un legante tipo tiol-carbossilato, l’acido 2-mercaptonicotinico. Lo zolfo presenta una variabilità maggiore di stati di ossidazione rispetto all’ossigeno e a questo si riconduce il particolare comportamento redox dei complessi con legami M-S. Per questo motivo la sintesi di complessi implicanti il legame metallo-zolfo è un’area di ricerca attiva soprattutto per quanto riguarda la progettazione di materiali con proprietà di conduzione, ottiche o magnetiche. In questo contesto sono stati considerati i complessi dei metalli di transizione con i leganti 1,2 ditiolato, altresi detti metallo bis-ditioleni. Nei metallo bis-ditioleni la variabilità degli stati di ossidazione del complesso senza grandi variazioni della geometria di coordinazione li rende adatti per la sintesi di materiali molecolari. In particolare, una via sintetica per l’ottenimento di tali materiali consiste nell’organizzare questi complessi via coordinazione ad un altro centro metallico, in maniera da ottenere composti a più alta nuclearità. Soprattutto per quanto riguarda il magnetismo molecolare, vi è la necessita di organizzare nella stessa molecola più centri paramagnetici. In questo lavoro di tesi, inizialmente dithioleni paramagnetici “classici” come [Cu(mnt)2]2- ,[Cu(tfadt)2]2-and [Ni(dmid)2].-, contenenti gruppi funzionali potenzialmente coordinanti sono stati impiegati come metallo-leganti verso complessi paramagnetici di Mn(III) o a valenza mista Mn(II)/Mn(III). Durante gli esperimenti condotti, è risaltata la reattività in soluzione dei metallo bis-ditioleni verso lo scambio di leganti che non ha condotto alla formazione del complesso polunucleare sperato, sebbene siano stati isolati composti potenzialmente interessanti. Alla luce di tutto cio, è stata intrapresa la sintesi di nuovi leganti 1,2 ditiolato opportunamente funzionalizzati con gruppi coordinanti quali gli eteri corona. La versatilità dei ditioleni verso la funzionalizzazione ha permesso di realizzare una serie di leganti con diverse dimensioni del macrociclo, in modo da poter modulare la selettività verso metalli di transizione ma anche verso ioni di lantanidi trivalenti. Sono stati sintetizzati a partire da questi leganti i complessi ditioleni di nickel, isolandoli in forma di anioni e aventi spin S=1/2. Sono state ottenuti complessi polimetallici Ni-Ni e Ni-Na. Inoltre è stato ottenuto un complesso bimetallico Ni-Ni. Tutti i complessi sono stati caratterizzati chimicamente. Inoltre, le proprietà magnetiche sono state indagate tramite misure di suscettività magnetica in funzione della temperatura, rivelando per il complesso polimetallico Ni-Ni una forte interazione fra le unità ditiolene costituenti il complesso. Il legante tiol-carbossilato acido 2- mercaptonicotinico è stato considerato per la sua versatilità alla coordinazione. In condizioni idrotermali e in presenza di Zn(II) e acido 2-mercaptonicotinico, è stato ottenuto un polimero di coordinazione dove il legante mercaptonicotinato funge da chelante S,O e lega a ponte monoatomico i vicini centri metallici. La stessa topologia non è stata ottenuta con il Ni(II). Cambiando le condizioni di reazione, finora solo il complesso monometallico Ni(II) bis-mercaptonicotinato è stato ottenuto. Le proprietà elettroniche correlate alla situazione di coordinazione S-Zn-O del polimero di coordinazione di Zn(II) sono state investigate per mezzo di calcoli teorici e misure sperimentali.
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Dolder, Stefan. « Tetrathiafulvalene (TTF) based ligands and their transition metal complexes : studies towards multifunctional materials combining conducting, magnetic and optical properties / ». Bern : [s.n.], 2006. http://www.zb.unibe.ch/download/eldiss/06dolder_s.pdf.
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Bräuer, Björn. « Synthesis of bis(oxamato) transition metal complexes and Ni nanoparticles and their structural, magnetic, optical, and magneto-optical characterization ». Doctoral thesis, Universitätsbibliothek Chemnitz, 2008. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-200800928.
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Im Rahmen dieser Arbeit werden ein- und mehrkernige Cu(II)- und Ni(II)-bis(oxamato)-Komplexe im Hinblick auf ihre magneto-optischen Eigenschaften gezielt hergestellt und strukturell charakterisiert. Über ladungs- und übergangsmetallinduzierte Abweichungen vom allgemeinen in der Literatur beschriebenen Reaktionsverhalten wird berichtet.
Aus Elektronenspinresonanz-Untersuchungen wird die Spindichteverteilung in den einkernigen Cu(II)-Komplexen abgeleitet. Die Beeinflussung dieser durch die Koordinationsgeometrie sowie die Auswirkungen auf die Superaustausch-Wechselwirkung werden diskutiert und mit Ergebnissen der Dichtefunktionaltheorie (DFT) verglichen. Dreikernige bis(oxamato)-Komplexe werden erstmals durch Spin-Coating auf Si(111)-Substraten aufgebracht und mit Hilfe der spektroskopischen Ellipsometrie sowie der Ramanspektroskopie untersucht und mittels DFT-Berechnungen ausgewertet. Magneto-optische Kerr-Effekt-Untersuchungen werden an dünnen Schichten dieser Komplexe sowie Phthalocyaninen durchgeführt.
Zum Vergleich werden die magnetischen und magneto-optischen Eigenschaften von Ni-Nanopartikeln in verschiedenen organischen Matrizen untersucht. Mit Hilfe der Photoelektronenspektroskopie wird das Oxidationsverhalten dieser studiert und es werden Rückschlüsse auf Ladungstransferprozesse zwischen den Matrizen und den Nanopartikeln gezogen.
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Witt, Alexander [Verfasser], Khusniyarov [Akademischer Betreuer] et Marat [Gutachter] Khusniyarov. « Transition Metal Complexes with Photoactive Ligands - Modulation of Magnetic Properties at Room Temperature / Alexander Witt ; Gutachter : Marat Khusniyarov ; Betreuer : Khusniyarov ». Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2018. http://d-nb.info/1156780950/34.
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Rouzhaji, Tuerhong. « Effect of environment on the electronic and magnetic properties of transition metals and rare-earth complexes ». Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAE006/document.
Texte intégralRésumé :
Cette thèse présente les résultats de mesures expérimentales effectués à basse température par les techniques de microscopie tunnel à balayage et de spectroscopie par tunnel à balayage (STS) sur les métaux de transitions phthalocyanines déposées sur les surfaces de métaux nobles. Les mesures STM/STS ont été effectuées pour les molécules MnPc et CuPc adsorbées sur les surfaces Ag (111) et Au (111) à la température expérimentale de travail de 4,5 K. Ces deux types de molécules présentent une différence substantielle de configurations d'adsorption, des comportements électroniques et magnétiques et des structures vibratoires moléculaire. Les études STM/STS ont principalement porté sur les propriétés magnétiques de ces molécules à travers l’effet Kondo et une attention particulière a été accordée à la molécule de MnPc en raison de son comportement magnétique plus intéressant issu de l'atome Mn central. Particulièrement, nous avons étudié l'évolution spectrale des structures électroniques et magnétiques du MnPc partant d'une molécule unique jusqu'à la structure bicouche ordonnée sur la surface Ag (111). En outre, les études STM/STS ont montré une preuve de couplage magnétique entre les moments magnétiques de l'atome de Co et de la molécule de MnPc ainsi que sa forte dépendance vis-à-vis du site d'adsorption de l'atome de Co. Ces études STM/STS sur ce système nous ont permis de comprendre l'effet des interactions molécule-substrat, molécule-molécule et molécules-atome sur les propriétés électroniques et magnétiques des molécules de MnPcThis thesis presents the results of low-temperature scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) studies on transition-metal phthalocyanines molecules on the noble metal surfaces. The STM/STS measurements have been performed for MnPc and CuPc molecules adsorbed on Ag(111) and Au(111) surfaces at the experimental working temperature of 4.5 K. These two types of molecules exhibit substantially different adsorption configurations, the electronic and magnetic behaviors and the molecule vibrational structures. The STM/STS studies have focused mainly on the magnetic properties of these molecules by means of Kondo effect, and special attention has been paid to MnPc molecule due to its more interesting magnetic behavior arising from the central Mn atom. Particularly we investigated the spectral evolution of electronic and magnetic structures of MnPc starting from a single molecule up to the ordered bilayer structures on Ag(111) surface. In addition, the STM/STS investigations showed an evidence of magnetic coupling between the magnetic moments of the Co atom and MnPc molecule and its strong dependence on the adsorption site of Co atom. These STM/STS investigations on this system allowed us to understand the effect of molecule-substrate, molecule-molecule and molecule-atom interactions on the electronic and magnetic properties of MnPc molecules
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Maurice, Rémi. « Zero-field anisotropic spin hamiltonians in first-Row transition metal complexes : theory, models and applications ». Doctoral thesis, Universitat Rovira i Virgili, 2011. http://hdl.handle.net/10803/37363.
Texte intégralRésumé :
Aquest treball presenta l’estudi teòric de l’anisotropia magnètica en complexos de metalls de transició, combinant esquemes de càlcul multiconfiguracionals relativistes amb derivacions analítiques basades en la teoria del camp del lligand, el que permet racionalitzar a través de conceptes senzills els resultats quantitatius obtinguts i interpretar les propietats estudiades.
Es desenvolupa primer una metodologia per extreure els paràmetres d’anisotropia en complexos mononuclears de metalls de transició. El mètode es basa en assignar els resultats d’un càlcul ab initio d’alt nivell a un Hamiltonià model mitjançant la teoria d’Hamiltonians efectius. Aquesta metodologia s’aplica a complexos de Ni(II), Co(II) i Mn(III) i es comprova que és aplicable de forma general a complexos mononuclears.
S’estén després la metodologia a complexos binuclears, pels quals l’Hamiltonià model usualment utilitzat té una base menys rigorosa. L’Hamiltonià efectiu obtingut per un complex binuclear de Ni(II) introdueix una nova parametrització amb termes addicionals de les interaccions anisotròpiques en sistemes polinuclears. Es tracta d’un procediment universal que proporciona valors precisos i a més és capaç de contrastar la consistència interna dels Hamiltonians models existents.
Per racionalitzar les correlacions magnetoestructurals dels paràmetres d’anisotropia en complexos de Ni(II) i Mn(III), es descriuen els mecanismes electrònics bàsics en base a consideracions de la teoria del camp del lligand. Aquest procediment proporciona regles senzilles per augmentar l’anisotropia, que poden ser aplicades en el disseny de nous materials.
Finalment, s’estudien les interaccions anisotròpiques simètriques i antisimètriques en compostos binuclears de Cu(II), interaccions de gran importància per explicar les propietats d’alguns materials d’interès tecnològic. Les interaccions antisimètriques s’extreuen a partir de càlculs ab initio d’estructura electrònica per primer cop en aquest treball. Es concentra l’atenció d’aquesta part en dos sistemes: el conegut complex binuclear de Cu(II) amb quatre ponts acetat, i l’òxid de coure en el que recentment s’ha evidenciat una fase ferroelèctrica.
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Meyer, Jennifer [Verfasser], et Gereon [Akademischer Betreuer] Niedner-Schatteburg. « Spin and orbital contributions to the magnetic moment of isolated transition metal clusters and complexes / Jennifer Meyer. Betreuer : Gereon Niedner-Schatteburg ». Kaiserslautern : Technische Universität Kaiserslautern, 2014. http://d-nb.info/1054636117/34.
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Griffin, Joanna Louise. « Investigations of the metal fluoride transition state and ground state analogue complexes of HAD superfamily proteins by nuclear magnetic resonance spectroscopy ». Thesis, University of Sheffield, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.574570.
Texte intégralRésumé :
Metal fluorides (MgF3-, AIF4 - and BeF3-) have been used to mimic the transition state and ground state of phosphate transfer enzymes. The aim of this thesis is to study how phosphate transfer enzymes are able to achieve rate enhancements of 1021 over the uncatalysed reaction, using the full complement of metal fluoride analogues. NMR and X-ray crystallography have been used synchronically to extend the current knowledge of phosphate transfer in β-phosphoglucomutase (βPGM) and phosphoserine phosphatase (PSP). The charge balance theory proposes that the active site of phosphate transfer enzymes is set-up to neutralise the negative charge on the substrate and has been proposed in the literature using phosphoglycerate kinase. Chapter 3 of this thesis shows that the charge balance hypothesis holds true for ~PGM and highlights the importance of local charge in the active site. Chapters 4 and 5 establish the use of BeF3- as a ground state analogue in ~PGM. Complexes in the absence and presence of substrate, have been fully characterised by 19F NMR, IH and 15N chemical shift analysis including backbone assignment and X-ray crystallography. Key residues involved in cap and core domain closure have been recognised through this analysis. A minor conformer of the βPGM:MgF3-:G6P TSA complex was observed in the 19F NMR spectrum. Chapter 6 establishes the nature of this complex as arising from a change in geometry from trigonal bipyramidal to octahedral geometry around the central magnesium ion in the metal fluoride moiety. The full complement of metal fluoride complexes of PSP have been formed and characterised by 19F NMR in chapter 7. The 19F chemical shift and sum isotope shift for each fluoride has been recorded in each complex and has been compared to the available X-ray crystal structures to establish that the NMR and crystallography data report on the same structures.
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Butrouna, Kamal H. « A Systematic Transport and Thermodynamic Study of Heavy Transition Metal Oxides with Hexagonal Structure ». UKnowledge, 2014. http://uknowledge.uky.edu/physastron_etds/24.
Texte intégralRésumé :
There is no apparent, dominant interaction in heavy transition metal oxides (TMO), especially in 5d-TMO, where all relevant interactions are of comparable energy scales, and therefore strongly compete. In particular, the spin-orbit interaction (SOI) strongly competes with the electron-lattice and on-site Coulomb interaction (U). Therefore, any tool that allows one to tune the relative strengths of SOI and U is expected to offer an opportunity for the discovery and study of novel materials. BaIrO3 is a magnetic insulator driven by SOI whereas the isostructural BaRuO3 is a paramagnetic metal. The contrasting ground states have been shown to result from the critical role of the strong SOI in the iridate. This dissertation thoroughly examines a wide array of newly observed novel phenomena induced by adjusting the relative strengths of SOI and U via a systematic chemical substitution of the Ru4+(4d4) ions for Ir4+(5d5) ions in BaIrO3, i.e., in high quality single crystals of BaIr1-xRuxO3(0.0 < x < 1.0) . Our investigation of structural, magnetic, transport and thermal properties reveals that Ru substitution directly rebalances the competing energies so profoundly that it generates a rich phase diagram for BaIr1-xRuxO3 featuring two major effects: (1) Light Ru doping (0 < x < 0.15) prompts a simultaneous and precipitous drop in both the magnetic ordering temperature TC and the electrical resistivity, which exhibits metal-insulator transition at around TC. (2) Heavier Ru doping (0.41 < x < 0.82) induces a robust metallic and spin frustration state. For comparison and contrast, we also substituted Rh4+(4d5) ions for Ir4+(5d5) ions in BaIrO3, i.e. BaIr1-xRhxO3(0.0 < x < 0.10), where Rh only reduces the SOI, but without altering the band filling. Hence, this system remains tuned at the Mott instability and is very susceptible to disorder scattering which gives rise to Anderson localization.
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Manrique, Salas Ester. « Development of new transition metal complexes for their use in sustainable catalytic processes and as antitumoral agents ». Doctoral thesis, Universitat de Girona, 2018. http://hdl.handle.net/10803/668830.
Texte intégralRésumé :
In this thesis we present the synthesis and characterization of different
types of ruthenium complexes containing N-donor ligands together with
monodentate ligands, along with their complete characterization through
spectroscopic and electrochemical techniques. The complexes have been
evaluated as catalysts for olefin epoxidation and nitrile hydration in
2/1
homogeneous phase. On the other hand, taking into account the importance and
advantages of the heterogeneous catalysis, we have carried out the
immobilization of some of these complexes on silica-type supports and
magnetic nanoparticles and we have evaluated their catalytic activity,
comparing them with the analogous homogeneous systems, and have been reused
for several runs maintaining high values of selectivity for the epoxide. Some
of the complexes together with other complexes previously synthesized in our
research group, have been tested as antitumoral agentsEn aquesta tesi es presenta la síntesi de diferents tipus de complexos de ruteni i manganès que contenen lligands N-donadors en combinació amb altres lligands monodentats, i la seva completa caracterització mitjançant tècniques espectroscòpiques i electroquímiques. Els complexos han estat avaluats com a catalitzadors en epoxidació d'olefines i hidròlisi de nitrils en fase homogènia. Per altra banda, tenint en compte la importància i els avantatges de la catàlisi heterogènia, s’ha dut a terme la immobilització d’alguns d’aquests complexos sobre suports tipus sílice i nanopartícules magnètiques i se n'ha avaluat l'activitat catalítica, comparant-los amb els anàlegs en fase homogènia, i s'han pogut reutilitzar durant diversos cicles mantenint alts valors de selectivitat per l'epòxid. Alguns dels complexos, juntament amb d'altres sintetitzats anteriorment al grup de recerca, han estat avaluats com agents antitumorals
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Baillie, Gordon M. « Preparation, spectral and magnetic studies on some first row transition metal complexes and an investigation into their performance as colourants for poly(vinyl chloride) ». Thesis, Edinburgh Napier University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.385997.
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Martin, Claudia [Verfasser], Jens [Akademischer Betreuer] Kortus, Jens [Gutachter] Kortus et Eliseo [Gutachter] Ruiz. « Density functional study of the electronic and magnetic properties of selected transition metal complexes / Claudia Martin ; Gutachter : Jens Kortus, Eliseo Ruiz ; Betreuer : Jens Kortus ». Freiberg : Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2014. http://d-nb.info/1220837512/34.
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Mougenot, Pierre. « Etude theorique ab initio scf et ci de complexes organometalliques binucleaires ». Université Louis Pasteur (Strasbourg) (1971-2008), 1988. http://www.theses.fr/1988STR13025.
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Analyse approfondie du spectre photoelectronique se(fe(c::(5)h::(5)))::(2)(no)::(2). Etude critique des resultats experimentaux anterieurs concernant le diamagnetisme suppose se(co(c::(5)h::(5)))::(2)(no)::(2). Bon accord avec l'experience dans l'etude theorique de l'etat fondamental du cation dirhodium tetraacetate dihydrate. Etude sur la nature de l'interaction metal-metal dans (v(c::(5)h::(5)))::(2) (c::(8)h::(8))
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Eelbo, Thomas [Verfasser], et Roland [Akademischer Betreuer] Wiesendanger. « Interaction of Transition Metal Adatoms and Dirac Materials investigated by Scanning Tunneling Microscopy and X-ray Magnetic Circular Dichroism / Thomas Eelbo. Betreuer : Roland Wiesendanger ». Hamburg : Staats- und Universitätsbibliothek Hamburg, 2014. http://d-nb.info/1050239199/34.
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Maigut, Joachim. « Investigation of structure, dynamic and solvent-interaction of transition-metal-aminopolycarboxylate complexes in solution = Untersuchungen zu Struktur, Dynamik und Solvensinteraktion von Übergangsmetall-Aminopolycarboxylat Komplexen in Lösung ». kostenfrei, 2008. http://www.opus.ub.uni-erlangen.de/opus/volltexte/2008/964/.
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Nguyen, Thi Ai Nhung. « Transition metal complexes of NHE ligands [(CO)4W-{NHE}] with E = C – Pb as tracers in environmental study : structures, energies, and natural bond orbital of molecular interaction ». Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-190482.
Texte intégralRésumé :
Quantum chemical calculations at BP86/TZVPP//BP86/SVP have been carried out for the Nheterocylic carbene and analogues complexes (tetrylene) [(CO)4W-NHE] (W4-NHE) with E = C – Pb. The tetrylene complexes W4-NHE possess end-on-bonded NHE ligands (E = C, Si), while for E = Ge and Sn, they possess slightly side-on-bonded ligands. The strongest side-on-bonded ligand when E = Pb has a bending angle of 102.9°. The trend of the bond dissociations energies (BDEs) for the W-E bond is W4-NHC > W4-NHSi > W4-NHGe > W4-NHSn > W4-NHPb. Analysis of the bonding situation suggests that the NHE ligands in W4-NHE are strong σ-donors and weak π-donors. This is because the tetrylenes have only one lone-pair orbital available for donation. The polarization of the W-E bond and the hybridization at atom E explain the trend in the bond strength of the tetrylene complexes W4-NHE. The W-E bonds of the heavier systems W4-NHE are strongly polarized toward atom E giving rise to rather weak electrostatic attraction with the tungsten atom which is the main source for the decreasing trend of the bond energies. The theoretical calculations suggest that transition-metal complexes tetrylenes [(CO)4W-{NHE}] (E = C – Pb) should be synthetically accessible compounds with tetrylenes NHE act as two-electron-donor ligands in complexesPhân tích cấu trúc và bản chất liên kết hóa học của hợp chất với kim loại chuyển tiếp chứa phối tử N-heterocyclic carbene và các đồng đẳng (tetrylene) [(CO)4W–NHE] (W4-NHE) với E = C – Pb sử dụng tính toán hóa lượng tử ở mức BP86/TZVPP//BP86/SVP. Cấu trúc của phức W4-NHE cho thấy các phối tử NHE với E = C, Si tạo với phân tử W(CO)4 một góc thẳng α = 180,0°, trong khi đó các phức W4-NHE thì phối tử NHE với E = Ge – Pb tạo liên kết với nhóm W(CO)4 một góc cong α < 180,0° và góc cong càng trở nên nhọn hơn khi E = Pb (α = 102.9°). Năng lượng phân ly liên kết của liên kết W-E giảm dần: W4-NHC > W4-NHSi > W4-NHGe > W4-NHSn > W4-NHPb. Tính toán hóa lượng tử trong phức [(CO)4W-{NHE}] (E = C – Pb) cho thấy phối tử tetrylene là chất cho electron. Điều này có thể do phối tử tetrylene chỉ giữ lại một cặp electron tại nguyên tử E để đóng vai trò là chất cho điện tử. Độ bền liên kết của phức W4-NHE được giải thích nhờ vào độ phân cực của liên kết W-E và sự lai hóa của nguyên tử trung tâm E. Nguyên nhân chính làm giảm dần năng lượng liên kết là do liên kết W-E của các phức nặng hơn W4-NHE bị phân cực mạnh về phía nguyên tử E dẫn đến lực hút tĩnh điện với nguyên tử W yếu dần. Hệ phức nghiên cứu được coi là hợp chất điển hình cho các nghiên cứu thực nghiệm
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GARNIER, AMALIA. « Processus metamagnetiques dans les systemes frustres rm#2x#2 (r = terre rare, m = metal de transition, x = si ou ge) ». Université Joseph Fourier (Grenoble), 1996. http://www.theses.fr/1996GRE10129.
Texte intégralRésumé :
Le but de ce travail est de montrer la richesse des comportements magnetiques des composes rm#2x#2 (r = terre rare, m = co, ni, ru, x = si, ge). Cette richesse ne necessite pas d'autres ingredients que la presence d'interactions magnetiques a longue portee et antagonistes (frustration), et d'anisotropie magnetocristalline: l'etude de systemes de type ising, x-y ou de faible anisotropie a permis d'illustrer les differents comportements associes. En ce qui d'un moment magnetique de l'etat o vers +m ou passage de l'etat -m vers l'etat o. Les processus concerne les systemes de type ising, nous avons mis en evidence, pour la premiere fois, l'existence de phases magnetiques mixtes ou coexistent des moments nuls et non nuls dans la structure magnetique. Un nouveau type de processus metamagnetique est associer a ces phases: passage metamagnetiques dans les systemes de type ising sont analyses quantitativement par le modele de champ moyen periodique: ce modele permet d'expliquer l'origine des sauts d'aimantation associes a des retournements d'une partie des moments, avec ou sans changement de periodicite. Les effets thermiques sont analyses et montrent l'evolution du vecteur de propagation lorsque la temperature decroit: il y a blocage du vecteur de propagation vers un vecteur de propagation decrivant une structure magnetique de plus courte periode pour les transitions de phase avec changement de periodicite. L'etude de composes a base de gadolinium a permis de montrer l'existence d'une anisotropie geante des interactions d'echange. L'etude comparative des series en fonction de la substitution de la terre rare, du metal de transition ou de x a permis d'isoler les parametres pertinents qui permettent de comprendre l'evolution des proprietes magnetiques dans les series etudiees
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Nguyen, Thi Ai Nhung. « Transition metal complexes of NHE ligands [(CO)4W-{NHE}] with E = C – Pb as tracers in environmental study : structures, energies, and natural bond orbital of molecular interaction : Research article ». Technische Universität Dresden, 2014. https://tud.qucosa.de/id/qucosa%3A29086.
Texte intégralRésumé :
Quantum chemical calculations at BP86/TZVPP//BP86/SVP have been carried out for the Nheterocylic carbene and analogues complexes (tetrylene) [(CO)4W-NHE] (W4-NHE) with E = C – Pb. The tetrylene complexes W4-NHE possess end-on-bonded NHE ligands (E = C, Si), while for E = Ge and Sn, they possess slightly side-on-bonded ligands. The strongest side-on-bonded ligand when E = Pb has a bending angle of 102.9°. The trend of the bond dissociations energies (BDEs) for the W-E bond is W4-NHC > W4-NHSi > W4-NHGe > W4-NHSn > W4-NHPb. Analysis of the bonding situation suggests that the NHE ligands in W4-NHE are strong σ-donors and weak π-donors. This is because the tetrylenes have only one lone-pair orbital available for donation. The polarization of the W-E bond and the hybridization at atom E explain the trend in the bond strength of the tetrylene complexes W4-NHE. The W-E bonds of the heavier systems W4-NHE are strongly polarized toward atom E giving rise to rather weak electrostatic attraction with the tungsten atom which is the main source for the decreasing trend of the bond energies. The theoretical calculations suggest that transition-metal complexes tetrylenes [(CO)4W-{NHE}] (E = C – Pb) should be synthetically accessible compounds with tetrylenes NHE act as two-electron-donor ligands in complexes.Phân tích cấu trúc và bản chất liên kết hóa học của hợp chất với kim loại chuyển tiếp chứa phối tử N-heterocyclic carbene và các đồng đẳng (tetrylene) [(CO)4W–NHE] (W4-NHE) với E = C – Pb sử dụng tính toán hóa lượng tử ở mức BP86/TZVPP//BP86/SVP. Cấu trúc của phức W4-NHE cho thấy các phối tử NHE với E = C, Si tạo với phân tử W(CO)4 một góc thẳng α = 180,0°, trong khi đó các phức W4-NHE thì phối tử NHE với E = Ge – Pb tạo liên kết với nhóm W(CO)4 một góc cong α < 180,0° và góc cong càng trở nên nhọn hơn khi E = Pb (α = 102.9°). Năng lượng phân ly liên kết của liên kết W-E giảm dần: W4-NHC > W4-NHSi > W4-NHGe > W4-NHSn > W4-NHPb. Tính toán hóa lượng tử trong phức [(CO)4W-{NHE}] (E = C – Pb) cho thấy phối tử tetrylene là chất cho electron. Điều này có thể do phối tử tetrylene chỉ giữ lại một cặp electron tại nguyên tử E để đóng vai trò là chất cho điện tử. Độ bền liên kết của phức W4-NHE được giải thích nhờ vào độ phân cực của liên kết W-E và sự lai hóa của nguyên tử trung tâm E. Nguyên nhân chính làm giảm dần năng lượng liên kết là do liên kết W-E của các phức nặng hơn W4-NHE bị phân cực mạnh về phía nguyên tử E dẫn đến lực hút tĩnh điện với nguyên tử W yếu dần. Hệ phức nghiên cứu được coi là hợp chất điển hình cho các nghiên cứu thực nghiệm.
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Mabad, Bouchra. « Modelisation du site d'oxydation de l'eau en photosynthese : complexes du manganese avec des bases de schiff polydentees ». Toulouse 3, 1987. http://www.theses.fr/1987TOU30103.
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Rouault, Philippe. « Les matériaux intermétalliques terres rares - métaux de transition et instabilité de l'antiferromagnétisme de bande ». Grenoble 1, 1989. http://www.theses.fr/1989GRE10105.
Texte intégralRésumé :
Nous presentons dans la premiere partie les avantages d'une fusion en levitation pour la preparation de composes intermetalliques terres rares-metaux de transition destines, a l'etude du magnetisme itinerant. Viennent ensuite les caracteristiques techniques du four a levitation que nous avons realise puis des exemples d'applications d'un tel procede d'elaboration. Dans la seconde partie, nous contribuons a l'etude de l'antiferromagnetisme de bande proche de l'instabilite a travers certaines phases de laves rmn#2. Grace aux informations experimentales sur les interactions d'echange extraites des diagrammes de diffraction neutronique et sur l'anisotropie, apprehendee a partir de spectres de resonance magnetique nucleaire, nous proposons un nouvel arrangement des moments magnetiques des atomes de manganese au sein de la structure magnetique du compose ymn#2. Nous discutons des effets de la frustration des interactions d'echange et de la forte anisotropie du manganese dans ce compose. Nous etudions egalement les proprietes magnetiques des composes pseudo-binaires y#1##xtb#xmn#2: la substitution d'atomes de terbium a ceux d'yttrium introduit, en sus de la tres forte frustration des interactions d'echange qui existent deja dans le compose ymn#2, une competition des energies d'anisotropie du terbium et du manganese. Il en resulte un ordre magnetique homogene complexe ainsi que l'apparition d'un ordre a courte distance que nous avons plus particulierement etudie dans le compose tbmn#2. Le terbium joue dans ce cas, le role d'une sonde des correlations de densite d'aimantation du manganese
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Fegy, Karine. « Ingénierie de matériaux moléculaires magnétiques : complexes de radicaux libres nitronyl nitroxydes bis-bidentes ; synthèse, structure et magnétisme ». Université Joseph Fourier (Grenoble ; 1971-2015), 1997. http://www.theses.fr/1997GRE10197.
Texte intégralRésumé :
La chimie de coordination des radicaux libres nitronyl nitroxydes est propice aux composes moleculaires magnetiques (aimants moleculaires ou transitions de spin). Cependant le caractere base de lewis faible du groupe nitroxyde >n-o limite dans de nombreux cas leur utilisation aux ions metalliques porteurs de ligands attracteurs. Pour eviter ce probleme, nous avons choisi de substituer les radicaux par des groupes donneurs. Ce travail concerne la synthese, la caracterisation structurale et l'etude des proprietes magnetiques de complexes d'ions metalliques avec les radicaux nitronyl nitroxydes porteurs des groupes imidazolyle (nitimh) ou benzimidazolyle (nitbzimh). La premiere partie est consacree a la complexation des radicaux non deprotones. Avec les ions metalliques de transition mn#2#+, ni#2#+, zn#2#+ et de terres rares gd#3#+, dy#3#+, plusieurs molecules mononucleaires qui sont des entites discretes, ont ete isolees. Leurs structures determinees par diffraction des rayons x sur monocristal montrent pour la premiere fois des centres metalliques entoures exclusivement de radicaux nitroxydes ; m(l)#3(mn#2#+, ni#2#+, zn#2#+) ou m(l)#4 (gd#3#+, dy#3#+)(l = nitimh ou nitbzimh). L'etude de leurs proprietes magnetiques revele des comportements varies. La seconde partie du travail decrit une serie de composes etendus du manganese(ii), obtenus lorsque les radicaux sont deprotones ; nitim#- ou nitbzim#-. La dimension des composes depend alors des conditions experimentales de deprotonation et du type de contre anions utilises. Quatre chaines ferrimagnetiques dans lesquelles alternent les ions manganese(ii) et les radicaux ont ete isolees, et leurs structures determinees. L'etude de leurs proprietes magnetiques met en evidence une aimantation spontanee au-dessous de temperature comprises entre 2 k et 4,5 k. Selon des conditions experimentales differentes, une serie de composes bidimensionnels a egalement ete synthetisee. La determination structurale de l'un d'entre eux montre qu'il s'agit de composes lamellaires constitues de feuillets mn#2(l)#3#+, separes par les contre anions. Ces composes sont des aimants en dessous de temperatures allant de 1,4 k a 40 k. Cette strategie est donc prometteuse et devrait ouvrir de nouvelles perspectives pour la construction d'edifices tridimensionnels.
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Barilero, Gilles. « Etude de quelques proprietes magnetooptiques et magnetiques des semiconducteurs semimagnetiques zn : :(1-x)mn ::(x)te et hg ::(1-x)mn ::(x)te ». Paris 6, 1987. http://www.theses.fr/1987PA066084.
Texte intégralRésumé :
L'effet d'echange entre les electrons de bande et les electrons d des ions manganese modifie les produits electroniques des alliages de zn dans un champ magnetique. L'effet zeeman de l'exciton permet de determiner la valeur des integrales d'echange de la bande de valence et de la bande de conduction dans ces composes. La presence d'interactions magnetiques entre les ions manganese est responsable des proprietes magnetiques. Les courbes d'aimantation des alliages dilues pour x5% en champ intense, a basse temperature, permettent de determiner la constante d'echange entre ions mn 1er voisins. Les alliages concentres presentent une phase de verre spin a basse temperature
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Arias, Olivares David. « Relation Among Localization, Delocalization and Physicochemical Properties. From Electron Density Databases to Magnetic Properties Effects of the acceptor unit in dyes with acceptor–bridge–donor architecture on the electron photo-injection mechanism and aggregation in DSSCs The role of Cr, Mo and W in the electronic delocalization and the metal–ring interaction in metallocene complexes ». Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS015.
Texte intégralRésumé :
Tout d'abord, nous évoquerons un aperçu général de l'analyse topologique basée sur la densité d'électronique, le trou d'échange-corrélation et la densité de paires. Une fois la densité électronique rappelée, l'analyse topologique de la densité électronique est expliquée, ainsi que la procédure de calcul des points critiques de la densité électronique, le calcul de la matrice hessienne de la densité électronique et la définition des points critiques à la surface. Tous ces outils topologiques permettent de caractériser la nature des liaisons chimiques parallèlement à l'indice basé sur la délocalisation. Afin de comprendre la nature des énergies et des interactions dans les systèmes, l'analyse d'interaction non covalente est expliquée et combinée à l'analyse de décomposition d?énergie. De plus, les états de transition seront étudiés en appliquant les orbitales naturelles pour la valence chimique (ETS-NOCV). Les concepts clés du magnétisme moléculaire sont abordés. Nous nous concentrons sur l'aimantation et la susceptibilité magnétique, les composants diamagnétiques et paramagnétiques provenant de toute réponse magnétique dans les systèmes. Les propriétés de champs magnétiques induits sont étudiés dans le but de comprendre l'aromaticité à travers de deux descripteurs, les déplacements chimiques indépendants du noyau et les densités de courant induit. En annexe à la théorie, l'interaction isotrope dans les composés dinucléaires est introduite pour expliquer et mesurer certaines erreurs trouvées dans la théorie de la fonctionnelle de densité (TFD). [...]The first property here analysed and related with electronic localization/delocalization is the aromaticity. Aromaticity is an important concept introduced by Kekulé; since then, theoreticians and experimentalist have tried to understand it in different groups of molecules analogues to benzene. The importance of this concept and how the aromaticity is affected by the chemical environment is important to understand and link some physicochemical properties. i.e., reactivity, stability, magnetic response. The physicochemical properties of interest are the electronic structure, the nature of bonds and organometallic interactions(differentiation between metallocenes and metallabencenes). Furthermore, the magnetic response and the study of building blocks as possible candidates to make nano-wires or new low-dimension magnetic materials. Finally, we try to understand the interaction and the errors involved in some properties theoretically computed like, the isotropic coupling between metals through aromatic (or organic) units that have become important benchmark molecules to study magnetic properties in inorganic as well as metal-organic systems [...]
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Ballou, Rafik. « Anisotropies magnétiques du cobalt dans les composés intermétalliques lanthanide-cobalt ». Grenoble 1, 1987. http://www.theses.fr/1987GRE10114.
Texte intégralRésumé :
Analyse phénoménologique des processus d'aimantation des composes YCo5 et GDCo5 mettant en évidence une anisotropie des interactions d'échangé Ln-Co liée à l'anisotropie de polarisation des électrons 5d de l'atome Ln. Etude de l'incidence de l'instabilité du magnétisme de bande 3d sur l'anisotropie magnétique dans les phases Ln2Co7 et LnCo3. Etude de l'anisotropie des systèmes à empilement quasi-unidimensionnel LnCo(1-epsilon ). Analyse de la sélection orbitale induite par les intégrales de transfert
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Berretil, Slimane. « Proprietes electroniques des semi-conducteurs magnetiques gamo : :(4)s ::(8), gamo ::(4)se ::(8), gamo ::(4)se ::(4)te ::(4) et ganb ::(4)s ::(8) ». Paris 6, 1987. http://www.theses.fr/1987PA066262.
Texte intégralRésumé :
Etudes effectuees en vue de preciser la nature des electrons qui participent ala conduction et au magnetisme de ces composes. Les composes, caracterises par la presence d'amas tetraedriques des ions metalliques mo et nb dans les bas etats d'oxydation, revelent des proprietes de magnetisme itinerant repondant au modele de stoner-wohlfarth avec les densites d'etats les plus elevees observees dans des composes intermetalliques 3d ou 4d. La rpe a confirme que les raies observees correspondant aux ions metalliques dans un etat s = 3/2 (ions mo**(3+) et nb**(3+)); leur elargissement est d'origine dipolaire retrecie par echange et les valeurs des integrales d'echange obtenues sont en bon accord avec celles obtenues a partir des temperatures de curie
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Rakoto, Harison. « Localisation electronique dans les amorphes metalliques : etude sous champ magnetique intense ». Toulouse 3, 1986. http://www.theses.fr/1986TOU30036.
Texte intégralRésumé :
Mesures de resistivite et de magnetoresistance sur divers alliages metalliques amorphes. Les resultats sont interpretes en termes de localisation faible, d'interactions interelectroniques et eventuellement de fluctuations supraconductrices. Dans le cas d'alliages supraconducteurs (lanthane-aluminium, lanthane-gallium, cuivre-zirconium), on discute les limites de validite des modeles theoriques actuels. Mise en evidence des effets de localisation sur la supraconductivite (vanadium-silicium) par des mesures de variation du champ critique avec la temperature. Pour ce qui est des alliages non supraconducteurs, l'analyse des resultats en champ magnetique fort permet une determination relativement precise des temps de relaxation inelastique et spin-orbite
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Berroir, Jean-Marc. « Proprietes electroniques des superreseaux hgte-cdte ». Paris 6, 1988. http://www.theses.fr/1988PA066074.
Texte intégral
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Giroud, Monique. « Etude expérimentale de supraconducteurs magnétiques : diagramme de phase de HoMo6S8 monocristallin et supraconductivité induite dans l'état ferromagnétique ». Grenoble 1, 1987. http://www.theses.fr/1987GRE10123.
Texte intégralRésumé :
Etude par des mesures de susceptibilite, de conductivite electrique et d'aimantation. Etude detaillee du diagramme de phase de homo::(6)s::(8); observation de transitions supraconductrices lors de cyclages en champ et en temperature, bien au-dessous du point de curie. Mise en evidence d'effet exceptionnellement faibles de l'echange sur la supraconductivite a partir de l'etude des champs critiques et de leur anisotropie; les transitions dans l'etat ferromagnetique sont expliquees par la reduction de l'induction magnetique lorsque le champ est antiparallele a l'aimantation spontanee. Recherche des effets des interactions d'echange sur la pente du champ critique a tc dans errh::(4)b::(4); mise en evidence d'une supraconductivite residuelle dans l'etat ferromagnetique, associee aux parois de bloch, dans le cas de sner::(4)rh::(6)sn::(18)
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Cheaito, Bassam. « Contribution à l'étude de la supraconductivité anormale du composé EuMo6S8 ». Grenoble 1, 1986. http://www.theses.fr/1986GRE10100.
Texte intégralRésumé :
Etude de monocristaux de eumo::(6)s::(8) et d'echantillons frittes de yb::(1,2-x)eu::(x)mo::(6)s::(8) basee sur des mesures de transport sous pression et sous champ magnetique, des mesures de la susceptibilite magnetique et des mesures rpe; mise au point d'un dispositif automatise de mesures de transport. Correlations entre la temperature de transition structurale, la remontee de la resistivite a basse temperature et la transition supraconductrice sous pression; effets de la composition des echantillons frittes. Mise en evidence d'une valeur tres elevee du coefficient de chaleur massique electronique. Discussion des proprietes anormales dans le cadre d'un modele de melange de phases triclinique et rhomboedrique et d'un modele de supraconductivite propre