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Rozprawy doktorskie na temat "Complexes de métal alcalino-terreux"
Huadsai, Wimonsiri. "Activation du dioxyde de carbone par des composés de Lewis hautement acidés". Electronic Thesis or Diss., Université de Toulouse (2023-....), 2024. http://www.theses.fr/2024TLSES053.
Pełny tekst źródłaThis research aimed to investigate the potential applications of Mg and Ca hydride complexes supported by ß-diketiminate and amidinate ligands for the reduction of CO2 molecules. The catalytic abilities of these complexes were explored in the context of hydroboration and hydrosilylation of CO2. In the first part of the study, we examined the reactivity of ß-diketiminato Mg and Ca hydrides with CO2. It was observed that the Mg hydride complex rapidly incorporated CO2, leading to the formation of various intermediates with different nuclearities. This involved the insertion of Mg—H bond into CO2, resulting in the generation of formate moieties. Under heat, hexameric formate complexes were formed through a "ligand flip" mechanism, releasing steric hindrances around the metal centers. For Ca hydride and CO2 reactions, in situ NMR analysis was mainly conducted. Additionally, a novel Mg amidinate dihydride complex was successfully synthesized and reacted with CO2 to yield a unique single product of dimeric formate Mg complex, in contrast to the ß-diketiminate scaffold, where several formate species were detected. The second part of the research focused on the catalytic hydroboration of CO2 using alkaline-earth hydride complexes. In particular, the Ca-based system demonstrated high efficiency in the production of the four-electron reduction of CO2 or BBA product. This was the first example of using Mg and Ca hydride compounds to catalyze the hydroboration of CO2, selectively producing the BBA product. The in situ generated BBA was further used as a methylene transfer reagent in condensation reactions with thiols, resulting in the formation of novel stable hemithioacetal [RS—CH2—OBR2] compounds under mild and neutral conditions. Activation of the hemithioacetal compounds was achieved under acidic conditions, leading to the formation of dithioacetals and hemithioaminals. The condensation of the second OBR2 fragment with secondary amines, which act as stronger nucleophiles, resulted in the generation of aryl methyl sulfides [RS—CH2—NR2]. In the final section, we investigated the tandem hydrosilylation of CO2 using various hydrosilanes in combination with [Ae]-based hydride complexes and Lewis acid B(C6F5)3 as catalysts. This research expanded on previous studies of Mg-mediated hydrosilylation of CO2 and introduced the first example of Ca-catalyzed CO2 hydrosilylation with hydrosilanes. The effectiveness of reducing CO2 to CH4 or bis(silyl)acetal [H2C(Ph3SiO)2] or BSA depended on the nature of the silanes and the steric hindrances around the substrate Si—H bond. The choice of [Ae] catalyst also significantly influenced the overall reaction rate. Furthermore, Eyring and Arrhenius analyses provided insight into the activation parameters for reducing CO2 by certain catalysts, revealing that this reaction is primarily governed by an entropic contribution. In summary, this research has demonstrated the reactivity of Mg and Ca hydride complexes for CO2 reduction and explored their applications in hydroboration and hydrosilylation reactions. Future investigations may explore mechanistic possibilities, kinetic differences, and the reactivity of group 2 metal hydride complexes with carbon monoxide for CO homologation
Hautreux, Mélanie. "Spectrométrie de masse de complexes moléculaires et macromoléculaires de cations alcalins et alcalino-terreux". Paris 11, 2002. http://www.theses.fr/2002PA112266.
Pełny tekst źródłaThe aim of this work is the study of the complexation of alkali and alkaline-earth metal cations with biologic molecules in the gaz phase. After a description of experimental methods used in this work we present results relative to the study of alkali cations and ammonium complexes with crown ethers formed by electrospray. One of the most important question in this field is to evaluate if the species observed in the mass spectra are representative of complexes formed in the solution phase. Some experiments of energy-resolved mass spectrometry permit to establish a relation between the internal energy laid on ions during ionization and their stability. These experiments led us to show that the relative intensities observed in mass spectra do not permit to establish directly a selectivity order of cations in solution. The structural study in LSl-MS/MS and in ESI-MS/MS of complexes of alkali cations and calcium with ionophorous compounds led us to consider their relative stability in the gas phase and to locate some sites of complexation. Then, we investigated the effect of basic organic compounds in the solution phase on the ionization of various proteins. Physicochemical characters of bases and the structure of macromolecules determine the charge states and the stability of proteins observed in electrospray mass spectra. These results were applied successfully to calmodulin/calcium complexes, the stability of these ionic species being reinforced by use of basic buffers
Le, Thi Kim-Thoa. "Luminescence de l'europium divalent dans les sulfures de magnésium ou d'éléments alcalino-terreux (sulfures MS, thioaluminates et thiosilicates)". Phd thesis, Université Sciences et Technologies - Bordeaux I, 1989. http://tel.archives-ouvertes.fr/tel-00168927.
Pełny tekst źródłaRenou, Franck. "Formation et réactivité de la paire électron solvaté-métal alcalino-terreux bivalent dans le tétrahydrofuranne : étude par radiolyse impulsionnelle". Paris 11, 2002. http://www.theses.fr/2002PA112222.
Pełny tekst źródłaThe reactivity of solvated electrons toward magnesium salts, and more generally, toward earth-alkaline metals has not yet been studied until those days. For magnesium, the formation of the unusual valence state is of interest because its nature and properties are at the center of mechanistics models on the formation of Grignard reagents, or organomagnesians, by which the metallic magnesium (valence 0) becomes divalent. We have conducted series of experiments in order to characterize this species by following the reaction of divalent magnesium salt (chloride or perchlorate) toward solvated electron generated by pulse radiolysis in tetrahydrofuran and some solvents for comparison. We showed experimentally and theoritically that there is formation of a pair solvated electron - metallic ion. This pair is obtained with perchlorates salts, then we followed its decay lasting few hundreds nanoseconds with a first order kinetic. This transient, whatever that would be the metal, has a broad spectrum which is composed by two bands around 1000 nm. It indicates the presence of a pair rather than a monovalent cation. SCF calculations confirmed it was the formation of a pair. This solvated electron - cation pair, even it has a short time life, has its own reactivity. We observed its capacity to reduce aromatic molecules (biphenyl, anthracen, chrysen, phenanthren and tetracen) and so we have estimated its redox potential which is include between - 2. 8 and - 2. 6 V_HNE. Furthermore, we brought out the reduction of alkyle halide (alkylic, phenylic and benzylic compounds) by the pair and the break of carbon-halogen bond which is corresponding to a step in the synthesis of Grignard reagents. In all cases, we determined mechanisms and kinetics of these different reactions
François, Michel. "Propriétés structurales, magnétisme et supraconductivité de germaniures et stannures ternaires de métaux de transition et lanthanoides ou alcalino-terreux". Nancy 1, 1986. http://www.theses.fr/1986NAN10132.
Pełny tekst źródłaMorel-Desrosiers, Nicole. "Contribution a la thermodynamique des solutions de cryptates alcalins et alcalino-terreux dans l'eau et le methanol". Clermont-Ferrand 2, 1987. http://www.theses.fr/1987CLF2E374.
Pełny tekst źródłaGerey, Bertrand. "Complexes homo- et hétéro-nucléaires de manganèse et de métaux alcalino-terreux : vers des modèles du centre de dégagement d'oxygène du photosystème II". Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAV041/document.
Pełny tekst źródłaThis thesis is focused on the development and characterization of new homo- and heteronuclear complexes of manganese and alkaline-earth metals for the modelization of the Mn4CaO5 inorganic cluster of the OEC of photosystem II.New ligands incorporating a varied number of pyridine-carboxylate groups and based on the tris-(2-picolyl)amine and bis-(2-picolyl)ethylamine architectures have been synthesized. These ligands enabled the isolation of Ca2+ and Sr2+ homonuclear complexes as well as heteronuclear MnII–Ca complexes. Part of these species have been characterized (among other models) by Ca XAS spectroscopy, enabling the calibration of this technique for the study of more complex systems such as the OEC.Furthermore, a new family of MnII3M’ (M’ = Li+, Ca2+, Sr2+, Mn2+) tetranuclear complexes has been isolated, based on a trinuclear Mn2+ metallamacrocyclic architecture hosting a M’ cation in the formed cavity. These complexes exhibited an original electrochemical behavior, displaying three successive reversible redox processes in oxidation whose potentials vary depending on the metal M’. These species demonstrated an excellent stability in solution, even at the +III oxidation state of manganese. Similar homonuclear M3M (M = Fe2+, Co2+) complexes have been isolated.Finally, binuclear Mn3+ complexes bridged by oxo ligands have been isolated, as well as their Mn2+ precursors. Moreover, a mixed-valence Mn2+/Mn3+ metallamacrocyclic cluster incorporating calcium has been synthesized, revealing the first example of a manganese(II) bridged by an hydroxo ligand to Ca2+ ions
LYAZGHI, RACHID. "L'ionophore lasalocide et ses complexes avec les alcalins et les alcalino-terreux en systemes homogene et heterogene : etude thermodynamique et par spectroscopie rmn". Clermont-Ferrand 2, 1991. http://www.theses.fr/1991CLF21314.
Pełny tekst źródłaBellini, Clément. "Complexes de baryum et autres métaux divalents du bloc principal pour la catalyse homogène de couplages déshydrogénants". Thesis, Rennes 1, 2016. http://www.theses.fr/2016REN1S057/document.
Pełny tekst źródłaIn the past two decades, heavier alkaline-earth (Ca, Sr, Ba) complexes have emerged as highly efficient and biocompatible precatalyst for hydroelementation or polymerisation reactions. This PhD thesis describes the synthesis and characterisation of heavier alkaline-earth complexes and their applications as precatalyst for cross-dehydrocoupling of hydrosilanes and amines. The homoleptic precatalyst Ba[CH(SiMe₃)₂]₂(THF)3 displayed high catalytic activity (TOF up to 3600 h⁻¹ ; TON up to 396), with excellent chemoselectivity in reaction of (di)amines with (di)hydrosilanes. Combination of experimental and DFT investigations (collaboration with Dr. Sven Tobisch) revealed the reactions proceed by nucleophilic attack of a metal amide at the incoming silane and subsequent turnover-limiting hydrogen transfer to the metal center. Development of synthesis of oligo- and polysilazanes was performed using our best barium precatalysts. Cyclic or linear polycarbosilazanes (Mw up to 10 000 g.mol⁻¹) were also produced by fast and controlled barium-catalyzed N-H/H-Si polycondensation. In a collaboration with Prof. Silvestru from Babeş-Bolyai University (Cluj-Napoca, Roumanie), synthesis of interesting zinc, cadmium, mercury and lead complexes were achieved in complement of this work
BOUYER, FREDERIC. "Etude analytique, par des techniques de modelisation, de l'influence de cations alcalins ou alcalino-terreux sur la stabilite et la reactivite de complexes de l'aluminium(iii) avec des ions halogenures ou oxydes". Paris 6, 1995. http://www.theses.fr/1995PA066549.
Pełny tekst źródłaCzęści książek na temat "Complexes de métal alcalino-terreux"
"Chapitre 12 - Liaisons métal-carbone ioniques et polaires : complexes des métaux alcalins, alcalino-terreux, lanthanides et actinides". W Chimie organométallique et catalyse, 297–320. EDP Sciences, 2020. http://dx.doi.org/10.1051/978-2-7598-1106-9-016.
Pełny tekst źródła"Chapitre 12 - Liaisons métal-carbone ioniques et polaires : complexes des métaux alcalins, alcalino-terreux, lanthanides et actinides". W Chimie organométallique et catalyse, 297–320. EDP Sciences, 2020. http://dx.doi.org/10.1051/978-2-7598-1106-9.c016.
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