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1	Zwitterionic late transition metal alkene polymerisation catalysts containing aminofulvene-aldiminate (AFA) ligands Rahman, Mohammed Mahmudur January 2010 (has links) Over recent years significant progress has been made in the design and development of late transition metal cationic catalysts for olefin polymerisation. Never-the-less, the activation of catalyst precursors and generation of active species still remains a challenge. In this respect, zwitterionic catalysts could offer a range of advantages over the traditional two component catalytic systems. For example, stable zwitterions are well-defined, single component catalysts which do not require Lewis acid co-catalysts for activation. Therefore, this eliminates the possibility of anions coordinating to the active site and could provide highly active catalysts. Moreover, this could reduce the production costs. In this thesis the 6-aminofulvene-2-aldiminate (AFA) ligand system has been employed to develop zwitterionic, charge-neutral complexes, analogues of Brookhart-type cationic alkene polymerisation catalyst containing 1,2-diimine ligand. Chapter 1 of the thesis provides a comprehensive literature review of the late transition metal (Group 10) α-diimine catalytic systems and the zwitterionic early and late transition metal alkene polymerisation catalysts. Chapter 2 describes the synthesis and characterisation of some novel zwitterionic complexes [(Ph2AFA)Pd(Me)(DMAP)], [(Ph2AFA)(N,N-dimethylbenzylamine-2-C,N)- Pd(II)] and [(Ph2AFA)Ni(η 3-C3H5)] and their possible application as catalyst precursors in alkene polymerisation. In principle, upon activation these complexes should exhibit higher catalytic activity. The ideal catalyst precursor for a highly active palladium based system would be a halide-bridged dimer of the form [(Ph2AFA)Pd(μ-X)]2. Chapter 2 describes several efforts towards the synthesis of such complexes using a range of R2AFA ligands. Even with the introduction of bulky N-substituents such as cyclohexyl or tert-butyl, the halidebridged dimers could not be synthesised. Instead, the reaction between the deprotonated ligand and [PdCl2(NCPh)2] provides bis-chelated complexes [(R2AFA)2Pd]. In order to introduce more steric bulk into the AFAH ligand which might lead to a halide-bridged dimer, two more ligands N,N’-bis(2,6-diisopropyl)phenyl-6-aminofulvene-2-aldimine and N,N’-di-(2,4,6-trimethyl)phenyl-6-aminofulvene-2-aldimine have been synthesised and characterised. It has been found that the presence of the 2,6-diisopropylphenyl substituents in N,N'-bis(2,6-diisopropyl)phenyl-6-aminofulvene-2-aldimine not only prevents the coordination of two ligands to the same metal, but precludes complexation all together. Chapter 2 also describes several efforts to develop a hemi-labile complex for alkene polymerisation. Chapter 3 describes the synthesis of metalloligands of aminofulvene-aldimine (AFA) and corresponding bimetallic complexes. The AFA ligand affords transition metal complexes via both η 5- as well as κ 2-coordination modes. A new synthetic methodology has been developed to synthesise metalloligands [CpRuII(Ph2AFA)H][BF4], [CpRhIII(Cy2AFA)H][BF4]2 and [CpRhIII(Cy2AFA)]- [BF4]. The basicity of the monocationic Rh metalloligand is found to be significantly lower than that of its Ru analogues. This is significant as it opens a potentially easy synthetic route to bimetallic complexes. The bimetallic complex [CpRhIII(Cy2AFAPdCl2)][BF4] has been developed for alkene polymerisation in an attempt to investigate the charge effect in alkene polymerisation catalysis. Upon activation this monocationic Rh/Pd bimetallic complex would provide a dicationic active species which would in principle be a more highly active catalyst than the Brookhart mono cationic diimine catalysts. Chapter 4 describes all the experimental procedure and polymerisation tests in this thesis. 541.39
2	Immobilisation de catalyseurs moléculaires de polymérisation d’oléfines sur nanomatériaux / Immobilization of molecular late transition metal polymerization catalysts on nanomaterials Zhang, Liping 24 January 2014 (has links) Le présent travail de thèse décrit le développement de systèmes actifs de polymérisation d’oléfines basés sur des métaux de fin de transition (nickel et fer) supportés sur des nanomatériaux. Le chapitre I décrit l’état de l’art des systèmes catalytiques supportés ou non pour la polymérisation d’oléfines. Dans le chapitre II, nous décrivons la polymérisation de l’éthylène en utilisant des catalyseurs de nickel contenant un groupement –NH2 pour leur immobilisation covalente sur nanotubes de carbone ; montrant l’influence positive de l’immobilisation : les catalyseurs ainsi supportés sont en effet à la fois plus actifs et conduisant à des polymères de plus haut poids moléculaire. Dans le chapitre III, des complexes de fer contenant un groupement pyrène sont décrits et immobilisés sur nanotubes de carbone par interaction non covalente π-π. Dans ce cas, à la fois les systèmes homogènes et leurs analogues supportés catalysent la réaction de polymérisation de l’éthylène avec des activités particulièrement élevées. Il a également pu être mis en évidence l’importante influence du support carboné sur les performances du système catalytique ainsi que sur la structure des polymères obtenus. Différents types de complexes de nickel contenant un ligand imino-pyridine et différents groupes polyaromatiques ont été synthétisés et leur utilisation en polymérisation de l’éthylène est décrite dans le chapitre IV. L’influence de l’addition de faibles quantités de matériaux nanocarbonés (nanotubes de carbone ou graphène) au milieu réactionnel a ainsi été étudiée. Le graphène s’est dans ce cas révélé particulièrement bénéfique sur les performances du catalyseur. Enfin, le chapitre V décrit la polymérisation de l’isoprène à l’aide de catalyseurs de fer contenant des groupements polyaromatiques permettant leur immobilisation à la surface de nanoparticules de fer. Ces systèmes ont ensuite pu être confinés dans des nanotubes de carbone. Les systèmes catalytiques décrits sont particulièrement actifs produisant des polyisoprènes à température de transition vitreuse élevée et avec une haute sélectivité trans-1,4-polyisoprène. / This present thesis deals with the development of active olefin polymerization catalysts based on late transition metal (nickel and iron) imino-pyridine complexes supported on nanomaterial. Chapter I gives a comprehensive literature review of unsupported and supported ethylene polymerization catalyst. In Chapter II we report the ethylene polymerization studies using nickel complexes containing an –NH2 group for covalent immobilization on multi-walled carbon nanotubes (MWCNTs) of the corresponding precatalysts. Comparison of the homogeneous catalysts with their supported counterparts evidenced higher catalytic activity and higher molecular weights for the polymers produced. In Chapter III, iron complexes containing a pyrene group have been synthesized and immobilized on MWCNTs through non-covalent π-π interactions between pyrene group and surface of MWCNTs. Activated by MMAO, both the iron complexes and immobilized catalysts show high activities for ethylene polymerization. It was possible to evidence that MWCNTs have a great influence on the catalytic activity and on the structure of the resulting polyethylenes. Imino-pyridine nickel complexes containing various kinds of aromatic groups have been synthesized in Chapter IV and polymerization conditions in the presence and in the absence of nanocarbon materials, such as MWCNTs or few layer graphene (FLG), are discussed. For those nickel catalysts bearing 1-aryliminoethylpyridine ligands, the presence of MWCNTs in the catalytic mixture allows the formation of waxes of lower molecular weight and polydispersity, whereas the presence of FLG proved to be beneficial for the catalytic activity. In Chapter V, isoprene polymerization catalyzed by iron complexes containing polyaromatic groups and non-covalently supported on nanoparticles and confined into the inner cavity of MWCNTs (Cat@NPs and Cat@NPs@MWCNTs) are investigated. Iron complexes show excellent activity for the isoprene polymerization and produced high glass temperature polyisoprene with a high trans-1,4-polyisoprene selectivity. Polymer nanocomposites are produced by supported catalysts and, transmission electron microscopy (TEM) evidenced efficient coating of the resulting polyisoprene around the oxygen sensitive iron nanoparticles. Ethylène polymerisation Isoprène polymerisation Métaux de fin de transition Couches de graphènes Particules de fer Particles catalyseurs supportés Capacité de protection Ethylene polymerization Isoprene polymerization Late transition metal catalyst Multi-walled carbon nanotubes Few layer graphene Iron particles Particles supported catalyst Protective ability Nanocomposites
3	Investigations into cyclopropanation and ethylene polymerization via salicylaldiminato copper (II) complexes Boyd, Ramon Cornell 23 January 2007 Two distinct overall research objectives are in this Masters thesis. Very little relates the two chapters apart from the ligands. The first chapter addresses diastereoselective homogeneous copper catalyzed cyclopropanation reactions. Cyclopropanation of styrene and ethyl diazoacetate (EDA) is a standard test reaction for homogeneous catalysts. Sterically bulky salicylaldimine (SAL) ligands should select for the ethyl trans-2-phenylcyclopropanecarboxylate diastereomer. Steric bulk poorly influences trans:cis ratios. Salicylaldiminine ligands do not posses the correct symmetry to affect diastereoselectivity. The SAL ligand belongs to the Cs point group in the solid state. Other ligand motifs are more effective at altering the trans:cis ratios. The second chapter addresses the general route toward successful copper(II) ethylene polymerization catalysts. Catalytic activity of the copper(II) complexes is very low. Polymer chain growth from a copper catalyst is very unlikely. Copper-carbon bonds decompose by homolytic cleavage or C-H activation. Copper-alkyls and aryls readily decompose into brown colored oils and salts with different colors. Ligand transfer to trimethylaluminum (TMA) appears to explain low yield ethylene polymerization. bulky migratory insertion mechanism coordination/insertion methodology d-block metal late transition metal phenolic ring coordination number ketimine precatalysts ketimine nitrogen bis(salicylaldiminato)copper(II) ratio cyclopropane steric bulk salicylaldiminato TMA salt trimethylaluminum aryl oil alkyl copper-aryls copper-alkyls C-H activation homolytic homolytic cleavage copper(II) polymerization ethylene cis trans symmetry diastereomer salicylaldimine SAL EDA ethyl diazoacetate styrene cyclopropanation copper diastereoselective steric protection stable CH(SiMe3)2 intermediate catalytic activity associated TMA free TMA vacant coordination site hydrolysis Lewis acid halogen anionic anionic ligand donor ligand monodentate anionic ligand aluminum(III) monodentate polymer chain polymer chain aluminum-carbon bond bulky SAL ligand open coordination site first row transition metal PE paramagnetic high molecular weight polyethylene alkylate methylaluminoxane MAO anionic ligands arylate aluminum carbon aluminum carbon bond beta-hydrogen elimination beta hydrogen elimination Aufbau reaction Aufbau neutral dialkyl aluminum aluminum-alkyl aluminum alkyl copper(0)
4	Investigations into cyclopropanation and ethylene polymerization via salicylaldiminato copper (II) complexes Boyd, Ramon Cornell 23 January 2007 (has links) Two distinct overall research objectives are in this Masters thesis. Very little relates the two chapters apart from the ligands. The first chapter addresses diastereoselective homogeneous copper catalyzed cyclopropanation reactions. Cyclopropanation of styrene and ethyl diazoacetate (EDA) is a standard test reaction for homogeneous catalysts. Sterically bulky salicylaldimine (SAL) ligands should select for the ethyl trans-2-phenylcyclopropanecarboxylate diastereomer. Steric bulk poorly influences trans:cis ratios. Salicylaldiminine ligands do not posses the correct symmetry to affect diastereoselectivity. The SAL ligand belongs to the Cs point group in the solid state. Other ligand motifs are more effective at altering the trans:cis ratios. The second chapter addresses the general route toward successful copper(II) ethylene polymerization catalysts. Catalytic activity of the copper(II) complexes is very low. Polymer chain growth from a copper catalyst is very unlikely. Copper-carbon bonds decompose by homolytic cleavage or C-H activation. Copper-alkyls and aryls readily decompose into brown colored oils and salts with different colors. Ligand transfer to trimethylaluminum (TMA) appears to explain low yield ethylene polymerization. bulky migratory insertion mechanism coordination/insertion methodology d-block metal late transition metal phenolic ring coordination number ketimine precatalysts ketimine nitrogen bis(salicylaldiminato)copper(II) ratio cyclopropane steric bulk salicylaldiminato TMA salt trimethylaluminum aryl oil alkyl copper-aryls copper-alkyls C-H activation homolytic homolytic cleavage copper(II) polymerization ethylene cis trans symmetry diastereomer salicylaldimine SAL EDA ethyl diazoacetate styrene cyclopropanation copper diastereoselective steric protection stable CH(SiMe3)2 intermediate catalytic activity associated TMA free TMA vacant coordination site hydrolysis Lewis acid halogen anionic anionic ligand donor ligand monodentate anionic ligand aluminum(III) monodentate polymer chain polymer chain aluminum-carbon bond bulky SAL ligand open coordination site first row transition metal PE paramagnetic high molecular weight polyethylene alkylate methylaluminoxane MAO anionic ligands arylate aluminum carbon aluminum carbon bond beta-hydrogen elimination beta hydrogen elimination Aufbau reaction Aufbau neutral dialkyl aluminum aluminum-alkyl aluminum alkyl copper(0)

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