• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 11
  • 2
  • 2
  • Tagged with
  • 14
  • 14
  • 6
  • 4
  • 4
  • 4
  • 4
  • 4
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Coordination of multidentate N-heterocyclic carbene ligands to nickel / Coordination de ligands carbène N-hétérocyclique multidentes sur le nickel

Charra, Valentine 05 September 2014 (has links)
Le sujet de cette thèse porte sur la synthèse de ligands de type bis-NHC (carbène N-Hétérocyclique) et leur réactivité vis-À-Vis des complexes d’argent(I), de cuivre(I) et de nickel(II).Après avoir exploré les différentes méthodologies de synthèse des complexes de nickel(II) bis-NHC, le but était de tester leurs activités en catalyse d’oligomérisation de l’éthylène. Une série de nouveaux complexes d’argent(I) et de cuivre(I) fut synthétisée. Cinq voies furent testées pour la formation de complexes de nickel. Les résultats les plus probants furent obtenus par transmétallation à partir des complexes d’iodure ou de bromure d’argent(I). / The purpose of this work was the synthesis of bis-NHC (N-Heterocyclic carbene) ligands, theformation of the corresponding silver(I), copper(I) and nickel(II) complexes and the assessment ofthe catalytic activity of the bis-NHC nickel(II) complexes in ethylene oligomerization. A series of new bis-NHC silver(I) and copper(I) complexes was synthesized. Five different synthetic routes were tested for the formation of nickel(II) bis-NHC complexes. The most significant results were obtained by transmetalation from the silver(I) iodide or bromide complexes.
12

Synthèses et propriétés de cages moléculaires commutables / Synthesis and properties of switchable molecular cages

Kocher, Lucas 18 November 2016 (has links)
Ce travail s’inscrit dans le domaine des cages moléculaires, édifices dont la géométrie définit unecavité tridimensionnelle capable de contenir d’autres entités.L’objectif de cette thèse est la synthèse de cages moléculaires covalentes possédant despropriétés d’encapsulation et une taille modulables. Les cages synthétisées avec succèsincorporent des porphyrines de zinc ou bases libres, ainsi que huit ligands triazoles périphériques.Des molécules ont pu être encapsulées par coordination aux porphyrines ou par interactions π, cequi démontre la capacité de la cage à s’adapter à l’invité grâce à sa flexibilité. La coordinationd’ions argent(I) permet de passer d’une conformation aplatie à une conformation ouverte. Lecaractère commutable de la cage a été démontré par décoordination de ces ions. Enfin, lacoordination d’ions argent(I) aux ligands de la cage augmente la stabilité de deux ligandsditopiques, le DABCO et la pipérazine, au sein de la cavité. Elle permet aussi l’accès de la cavité àdes molécules non encapsulées en l’absence d’argent(I). Ces résultats démontrent le contrôleallostérique de l’encapsulation de molécules par un stimulus chimique. / This work belongs to the field of molecular cages, hollow structures enclosing a three-dimensionalcavity able to encapsulate other molecules.The goal of this thesis include the synthesis of molecular covalent cages with a controllablecavity size able to perform switchable guest encapsulation. A DABCO-templated click reactionafforded three flexible covalent cages, endowed with two zinc(II) or free-base porphyrins and eightperipheral triazole ligands. Various guest molecules could be encapsulated by coordination toporphyrins or π-π interactions, in an induced-fit mechanism, probing the ability of the cage to adaptto the guest thanks to its flexibility. Coordination of silver(I) ions to the peripheral triazoles allow toswitch from a flattened to an open and locked conformation. Removal of the ions proved thecommutability of the cage. Finally, coordination of silver(I) ions to triazole ligands increase thestability of two ditopic ligands, DABCO and piperazine, inside the cavity. It also allowed the accessto the cavity of molecules that were not otherwise encapsulated. These results shows the allostericcontrol of guest encapsulation by a chemical stimulus.
13

Síntese e cristaloquímica do 1-(4-carboxifenil)-3-(4-acetilamidofenil)triazeno e complexos de cobre(i), prata(I) e ouro(I) com o ligante 1-(4-nitrofenil)-3-(4-etoxicarboxifenil)triazenido / Synthesis and crystalchemistry of 1-(4-carboxyphenyl)-3-(4-acetylamidophenyl)triazene and complexes of copper(I), silver(i) and gold(I) with 1-(4-ethoxycarbonylphenyl)-3-(4-nitrophenyl)triazenide ligand

Amaral, Carlos Henrique Oliveira do 05 December 2007 (has links)
This work deals with the determination of the single crystal structure analysis of four triazenido complexes including gold(I), copper(I), silver(I), and the crystal structure of a free triazene molecule. Crystal data and refinement indices of 1-(4-carboxyphenyl)-3-(4- acetylamidophenyl)triazene (1) are: monoclinic system, space group P21/n, cell parameters a = 7.772(1), b = 9.7365(2), c = 19.55(3) Å, β = 93.435(1)º, Z = 4, R1 = 0.0394, wR2 = 0.0632. The crystal structure show that the molecule deviates significantly from planarity (r.m.s. 0.342 Å). The molecules of (1) are associated to a bi-dimensional supramolecular array in form of helix chains including classic hydrogen bonding in the [010] crystallographic direction. Crystal data and refinement indices of 1-(4-ethoxycarbonylphenyl)-3-(4-nitrophenyl)triazenide(triphenylphosfine)gold(I) (3) are: triclinic system, space group P(-1), cell parameters a = 9.8837(2), b = 12.6159(2), c = 13.0948(2) Å, α = 79,160(1)°, β = 78,411(1)°, γ = 73,731(1)°, Z = 2, R1 = 0.0271, wR2 = 0.0588. One deprotonated triazenido ligand and one triphenylphosfine molecule built the linear coordination geometry of gold(I). Crystal data and refinement indices of 1-(4-ethoxycarbonylphenyl)-3-(4-nitrophenyl)-bis-(triphenylphosfine)copper(I) (4) are: triclinic system, space group P(-1), cell parameters a = 10.9853(2), b = 14.6006(3), c = 16.0638(3) Å, α = 79.160(1)°, β = 78.411(1)°, γ = 73.731(1)°, Z = 2, R1 = 0.0370, wR2 = 0.0996. One deprotonated triazenido ligand and three neutral triphenylfosfine molecules complete the distorted tetrahedral coordination sphere of copper(I). Crystal data and refinement indices of trans-bis-1-(4-ethoxycarbonylphenyl)-3-(4-nitrophenyl)triazenide-bis-(pyridine)silver(I) (5) are: triclinic system, space group P(-1) with cell parameters a = 9.3123(4), b = 11.1234(5), c = 11.1914(5) Å, α = 71.165(3)°, β = 68.723(3)°, γ= 89.530(3)°, Z = 2, R1 = 0.0383 wR2 = 0.0856. Two deprotonated monodentate triazenido ligands and two pyridine molecules in trans position relative to each other in a eight-membered Ag2N6 fragment, perform the Tcoordination geometry of each silver(I) ion. Crystal data and refinement indices of Catena-[bis(μ2-ciano)-bis(triphenilphosfine)-di-silver(I)] (6) are: monoclinic system, space group P21/n with cell parameters a = 9.3174(4), b = 22.931(1), c = 16.1513(8) Å, β = 99.759(3)°, Z = 4, R1 = 0.0526, wR2 = 0.1337. Two neutral triphenilfosfine molecules and two cyanide ligands support the distorted tetrahedral coordination geometry of the silver(I) ion in a open catenated coordination polymer. / Este trabalho apresenta a determinação da estrutura cristalina e molecular de quatro complexos sendo um com ouro(I), outro com cobre(I) e dois complexos de prata(I), adicionalmente incluindo a estrutura cristalina e molecular de um composto triazeno livre O composto 1-(4-carboxifenil)-3-(4-acetilamidofenil)triazeno(1) cristaliza no sistema monoclínico, grupo espacial P21/n, com parâmetros de cela a = 7,7723(10) Å, b = 9,7365(2) Å, c = 19,355(3) Å, β = 93,4350(10)º, V = 1462,09(4) Å3, Z = 4, R1 = 0,0394, wR2 = 0,1093. A estrutura cristalina do pró-ligante (1) revela que a molécula não é planar (r.s.m. 0,3148Å) e que, as moléculas unem-se por ligações de hidrogênio na direção cristalográfica [010]. As ligações de hidrogênio são do tipo clássicas N H O, O H O e O H N, que se relacionam por operações de simetria formando um arranjo bidimensional. O composto (3) cristaliza do sistema triclínico, grupo espacial P(-1) com parâmetros de cela a = 9,8837(2) Å, b = 12,6159(2) Å, c = 13,0948(2) Å; α= 79,1600(10)°, β= 78,4110(10)°, γ = 73,7310(10)°; V = 1520,32(5) Å3 ; Z = 2. O refinamento desta estrutura conduziu aos índices de discordância R1 = 0,0271, wR2 = 0,0588. A esfera de coordenação do íon ouro(I) é formada por um ligante triazeno desprotonado e uma moléculas de trifenilfosfina. O composto (4) cristaliza no sistema triclínico, grupo espacial P(-1) com parâmetros de cela a = 10,9853(2) Å, b = 14,6006(3) Å , c = 16,0638(3) Å, α = 97,1150(10)°, β = 102,9530(10)°, γ = 110,8030(10)°; V = 2287,95(8) Å3 ; Z = 2. O refinamento desta estrutura conduziu aos índices de discordância R1 = 0,0370, wR2 = 0,0996. A esfera de coordenação do íon cobre(I) é formada por um ligante triazeno desprotonado e duas moléculas de trifenilfosfina. O composto (5) binuclear cristaliza no sistema triclínico, grupo espacial P (-1) com parâmetros de cela a = 9,3123(4) Å, b = 11,1234(5) Å, c = 11,1914(5) Å, α = 71,165(3)°, β = 68,723(3)°, γ = 89,530(3)°; V = 1014,56(8) Å3 ; Z = 2. O refinamento desta estrutura demonstrou os índices de discordância R1 = 0,0383, wR2 = 0,0856. A esfera de coordenação do íon prata(I) é formada por dois ligantes triazenos desprotonados e duas moléculas de piridina. O composto (6) polímero cristaliza no sistema monoclínico, grupo espacial P21/n com parâmetros de cela a = 9,3174(4) Å, b = 22,9314(14) Å, c = 16,1513(8) Å, β = 99,759 (3)°; V = 3401,0(3) Å3 ; Z = 4. O refinamento desta estrutura atingiu os índices de discordância R1 = 0,0526, wR2 = 0,1337. A esfera de coordenação do íon prata(I) é formada por dois ligantes trifenilfosfina e dois cianetos.
14

Catalyse à l'or (I/III) : de la réactivité au catalyseur, en passant par l'analyse structurale / Gold (I/III) catalysis : from reactivity to catalyst, through structural analysis

Hoffmann, Marie 26 June 2015 (has links)
La catalyse organométallique est l’un des outils les plus puissants de la synthèse chimique, car elle permet de réaliser des transformations sélectives et spécifiques selon le catalyseur employé. Dans ce contexte, les sels et complexes d’or ont émergé il y a une quinzaine d’années et se sont révélés très utiles et attractifs pour la synthèse organique, faisant preuve de propriétés particulières de type acide de Lewis à la fois π (alcyno- alcènophilie) et σ (oxo- azaphile). L’objectif initial de cette thèse a été d'approfondir l’étude de la réactivité de l’or au travers la mise au point de nouvelles réactions catalysées par l’or(I/III). Si la majorité des réactions développées en catalyse à l’or concerne des processus de type π, nous avons dans un premier temps, souhaité évaluer son potentiel dans une réaction qui repose sur une activation purement σ, la cyclisation de Nazarov. Cette réaction a ensuite été étendue à un processus de type cascade, combinant activations π et σ. De plus, la formation d’un sous-produit inattendu au cours de cette étude a orienté nos recherches vers un nouveau processus catalytique, le réarrangement de γ–acyloxy alcynylcétones en furanes. Par la suite, nous nous sommes aussi intéressés au potentiel de l’or dans les réactions asymétriques, ce qui a conduit au développement d’un nouveau type de complexes d’or chiraux basés sur des ligands de type NHC-oxazoline. Enfin, nous nous sommes proposés d’utiliser la spectroscopie RMN J-résolue hétéronucléaire (une méthode simple mais peu exploitée), pour répondre à des problèmes d’attribution structurale. / Organometallic catalysis is one of the most powerful tools in chemical synthesis, because, depending on the catalyst, it allows for selective and specific transformations. Thus, the reactivity of gold salts and complexes was revamped around fifteen years ago. Nowadays, they are considered as powerful and very attractive for organic synthesis, showing both π (alcyno- alcènophilie) and σ (oxo- azaphile) Lewis acid properties.The first objective of this thesis was to study the reactivity of gold catalysts by the development of new reactions catalyzed by gold(I/III). If most of the developed reactions in gold catalysis is related to π activation, we proved its potential in a reaction dealing with σ activation, the Nazarov cyclization. This reaction was then extended to a cascade process, combining both π and σ Lewis acidities. Moreover, the obtainment of an unexpected by-product during the study directed our research towards a new gold catalytic reaction, the formation of furans from γ-acyloxyalkynyl ketones. Subsequently, we were also interested in the potential of gold in asymmetric reactions, which led to the development of new chiral gold complexs, based on NHC-oxazoline type ligands. Finally, we proposed to use the heteronuclear J-resolved NMR spectroscopy (a simple but scarce method), to answer some structural assignment problems.

Page generated in 0.024 seconds