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1
Sackville, Emma. "Molecular iridium oxidation catalysts." Thesis, University of Bath, 2018. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.767567.
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Oxidation reactions of both inorganic and organic substrates are among the most important chemical transformations, with application in sustainable chemistry and chemical synthesis. A library of half sandwich IrIII oxidation complexes with varying ligands were synthesised (54-78% yield) and fully characterised (NMR, UV-vis, crystal data), in order to investigate the effect on catalyst activity for water and C-H oxidation reactions. The electrochemical transition of IrIII to IrIV was investigated (cyclic voltammetry (CV)) and found to vary between ligand sets, such that alkyl substituted compounds had a lower midpoint potential than aryl substituted. Solution speciation under aqueous conditions was also investigated for all complexes (UV-vis spectroscopy), as well as investigation into catalyst activation by oxidative loss of the pentamethylcyclopentadienyl ligand (1H NMR, UV-vis spectroscopy).The catalytic activity for complexes Ir1-Ir7 was investigated for water oxidation with chemical oxidants, by oxygen evolution assays with a Clark electrode. All complexes evolved oxygen to some extent, with ligand effects causing significant variation in the rate of water oxidation (4.60 mM min-1 to 0.02 mM min-1 with sodium periodate in pure H2O). Mechanistic studies including H/D kinetic isotope effects and reaction progress kinetic analysis showed primary KIEs of 1.3-2.5, indicating O-H cleavage to be in the rate determining step. Determination of the catalyst order revealed an order in iridium of 0.5-0.6 for Ir1-Ir6 and 0.9 for Ir7, which was proposed to be due differences in the activecatalyst species for Ir7.The complexes were also tested for C-H oxidation performance and followed by 1H NMR. The reaction profiles for precatalysts Ir1-Ir7 all showed a plateau conversion with C-H oxidation, varying between 52% - 88%, which was attributed to a competition reaction with water oxidation. The varying ligands impart C-H/water oxidation selectivity onto the catalysts. The C-H oxidation scope was extended by investigations into the oxidation of several terpene-based compounds were also conducted (gas chromatography mass spectrometry, 1H NMR).Comparison of the water oxidation activity of the catalysts as driven by electrochemical potential (as followed by Clark electrode and chronoamperometry) exposed surprising trends that did not correlate with the chemical oxidant data and highlights the importance of reaction conditions when comparing water oxidation activity. Catalyst immobilisation was also attempted with a range of metal oxide supports (indium tin oxide on fluorine doped tin oxide glass, BiVO4, Fe2O3) and analysis of the resulting electrode assessed by CV. Fourier transform alternating current voltammetry (FTACV) was employed in order to investigate the oxidation state of the iridium during electrochemical water oxidation, revealing a clear [Ir] redox transition at the foot of the catalytic wave, proposed to be a key transition to the active catalytic species.
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Fuente, Molina Verònica de la. "Ligand design for palladium and iridium selective catalysts." Doctoral thesis, Universitat Rovira i Virgili, 2011. http://hdl.handle.net/10803/34766.
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This doctoral thesis focuses on the synthesis of new ligands and their application in two types of catalytic process: a) palladium catalysed carbonylation reactions and b) asymmetric reactions (hydrogenation of challenge substrates and C-C bond formation).
In the first part of the thesis, the synthesis of a family of new diphosphine ligands and their application in Pd-catalysed carbonylation processes is described. These ligands were first used in the Pd-catalysed methoxycarbonylation of ethane, achieving high activity and selectivity. A mechanistic study on these catalytic systems revealed the resting state of this process. The new ligands were also applied in the aminocarbonylation and double-carbonylation of aryl iodides, achieving high level of chemoselectivity in each case. NMR studies on these systems led to the discovery and development of the first phosphine-free Pd-catalysed double-carbonylation of aryl iodides where the base used in the process revealed to also play a key role as ligand and nucleophile.
The second part of this thesis describes the synthesis of new phosphino-imidazoline ligands and their application in the Ir-catalysed asymmetric hydrogenation of unfunctionalised olefines and imines achieving moderate enantioselectivities. These ligands were also applied in the Pd-catalysed allylic substitution reactions, achieving excellent enantioselectivities for a wide range of substrates and nucleophiles. An efficient recovery of the catalytic system was carried out by anchoring a phosphino-imidazoline ligand onto a polymer support or using ionic liquids as reaction medium.
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Salih, Omar Abdullah. "Towards polymer supported iridium borylation catalysts for organic synthesis." Thesis, Durham University, 2016. http://etheses.dur.ac.uk/11715/.
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The first chapter contains a detailed explanation of the borylation of arenes using iridium catalysts with different ligands. Phosphine, N,N-aryl and carbene ligands have been studied previously for the borylation of substituted aromatic and heteroaromatic compounds. The importance of polymer supported catalysts is shown. Examples of polymer supported iridium catalysts for the borylation of arenes are given. Chapter 2 discusses the preparation of 2-arylquinoline and quinolone derivatives. These were prepared by reaction of 3-methoxy and 3,5-dimethoxy aniline with malonic acid to generate the 2,4-dichloro quinoline derivatives. These in turn were then coupled with a range of aryl boronic acids in Suzuki-Miyaura cross-coupling reactions. A study documents the borylation selectivity of 2-(4’-methoxyphenyl)-4-chloro-7-methoxyquinoline 230. Various conditions in Stille cross-coupling reaction were used to prepare nonsymmetrical 4,4’-substituted-2,2’-bipyridine derivatives 250 and 285 in chapter 3. These were prepared through coupling of stannyl pyridine 266 with 2-chloro- and bromo-4-substituted pyridine derivatives in presence of metal salts. Ligands 250 and 285 were evaluated in the borylation of m-xylene and compared to the activity of the literature standard ligand 4,4’-di-tert-butyl-2,2’-bipyridine dtbpy 22. Chapter 4 describes the preparation of 2,4,6-substituted pyridine derivatives. These compounds were prepared by one of two methods. The borylation of 2-chloro-4-substituted pyridine derivatives afforded the corresponding boronate esters, which were then coupled with a range of aryl halides. This was followed by an aromatic nucleophilic substitution reaction with a range of amines. Alternatively, aromatic nucleophilic substitution of 2-chloro-4-substituted pyridine derivatives with amines afforded the corresponding 2-aminopyridines. Subsequent borylation of these subtrates followed by Suzuki-Miyaura cross-copuling was also an effective strategy. Chapter 5 reports the synthesis of symmetrical phenanthroline 347 using the Altman protocol. Attachment of a linker to enable coupling to a polymer support afforded modified ligand 367. Phenanthrolines 347 and 367 were evaluated in the borylation of m-xylene compared to the commercially available 3,4,7,8-tetra-methyl-1,10-phenanthroline tmphen 66. The commercially available MCM-41 was chosen as a suitable polymer for the polymer supported iridium catalyst. Different strategies were investigated to attach the phenanthroline ligand to the polymer. These strategies involved attaching an amine linker to the polymer before coupling it with lithium phenanthroline carboxylate 368. Chapter 6 provides all the experimental details.
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Bode, Kirstin S. "OPTIMIZATION OF IRIDIUM AND RUTHENIUM CATALYSTS IN THE C-H OXIDATION OF ALKANES." Kent State University Honors College / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ksuhonors1620909877637546.
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August, David Philip. "Development of metallosupramolecular photoredox catalysts." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/23644.
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Supramolecular chemistry allows the rapid formation of complex systems through self-assembly. These systems often possess unique properties not observed for conventional covalent constructs and have potential applications in areas such as sensing, drug delivery and catalysis. Metallosupramolecular container compounds have been shown to catalyse reactions with both regio- and stereo-selectivity in methods analogous to enzyme type catalysis. Separately, visible-light photoredox catalysis has recently gained considerable interest as an efficient, green and mild method for the rapid synthesis of many chemical compounds. In order to combine the favourable properties of both supramolecular catalysis and visible-light photoredox catalysis, a number of photoredox active metallosupramolecular assemblies were designed, synthesised and analysed. Initial steps were taken to stabilise a known iridium-based M6L4 luminescent cage compound to allow guest encapsulation to take place. The incorporation of isocyanide donors as strong ligands improved the stability of model compounds but synthesis of an analogous three-dimensional assembly was unsuccessful. Instead, a “complex-as-ligand” approach was taken that allowed the straight-forward formation of Pd2L4 systems from a range of photoactive iridium complexes. Importantly, unlike many other photoactive systems, the complexation to palladium did not drastically affect the photoredox properties of the constituent iridium complexes. Multiple approaches were then taken to improve both the stability and guest binding properties of the photoactive assembly in an effort to achieve supramolecular photoredox catalysis. Utilising a model system, a general method was thus developed for enhancing the association constants of neutral guests in organic solvents by switching to large, non-coordinating counter ions that provided reduced competition for the internal binding site. In combination with this increased binding affinity, a range of guest properties were adjusted by association with the hydrogen bond donor environment of the internal cavity. The encapsulation of quinone based oxidants led to unexpected and novel reaction pathways not observed in the bulk phase. As such, this work represents a significant advancement in development of metallosupramolecular systems capable of regio- and stereo-selective photoredox catalysis.
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Leung, Ka Ho. "Oligonucleotide-based lunimescent detection platform utilizing iridium (III) complexes." HKBU Institutional Repository, 2015. https://repository.hkbu.edu.hk/etd_oa/163.
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Luminescent transition metal complexes have arisen as viable alternatives to organic dyes for sensory applications due to their notable advantages. This thesis aimed to synthesize different kinds of Ir(III) complexes, explore their interactions with DNAs and investigate their application for the construction of label-free oligonucleotide-based sensing platforms. A series of Ir(III) complexes incorporating a variety of C^N and N^N donor ligands were synthesized and were shown to exhibit G-quadruplex-selective binding properties via emission titration, UV/vis titration, fluorescence resonance energy transfer melting and G-quadruplex fluorescent intercalator displacement experiments. These G-quadruplex-selective Ir(III) complexes were utilized as signal transducers to monitor the conformational changes of oligonucleotides in label-free oligonucleotide-based luminescent detection platforms for metal ion (Sr2+), small molecules (GSH and ATP), protein (human neutrophil elastase) and enzyme activities (polymerase, hepatitis C virus NS3 helicase).
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Getton, Frederick P. "Design of metal oxide catalysts." Thesis, Brunel University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314049.
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Lapido, Folami Tesileem. "Oxidative addition of N-H and O-H bonds to iridium: developing active catalysts for N-H and O-H additions to unsaturates." Diss., Virginia Tech, 1991. http://hdl.handle.net/10919/39829.
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The oxidative addition of the N-H bond of both heterocyclic and acyclic amines and the O-H bond of phenols, water and carboxylic acids to iridium(I) trimethylphosphines complexes was studied and the reactivity of the resulting hydrido amido-, aryloxo- and carboxylato iridium(III) complexes was investigated. Oxidative addition of the N-H bond of pyrrole, indole, 3-methylindole, 7-azaindole, carbazole and aniline to [Ir(COD)(PMe₃)₃]CI (1a) (COD = 1,5-cyclooctadiene) produces merIr( NR₂)H(PMe₃)₃CI (2a-f) complexes. That these amines were bound to iridium through an Ir-N bond was established by ¹H, ³¹P and ¹³C NMR spectroscopy, IR spectroscopy, C-H analyses and single crystal x-ray diffraction. Similarly, oxidative addition of the O-H bond of phenol, p-cresol, 3,5-dimethylphenol, and water to [Ir(COD)(PMe₃)₃]CI (la) produces mer-Ir(OR)H(PMe₃)₃C1 (5a-c and 6) which were characterized by ¹H, ³¹P and ¹³C NMR spectroscopy, C H analyses and single crystal x-ray diffraction. A preliminary study of the reactivity of both the amido and aryloxo complexes suggests that because of the increased electron affinity of the heteroatoms involved (N or 0), there is high electron density at the heteroatoms in these complexes and therefore the M-N or M-O bond can heterolyze more easily than M-C bonds. This increased tendency of the M-N or M-O bond to heterolyze leads to decomposition reactions when attempts are made to open up a coordination site at the metal center by removing the chloride ligand.Ph. D.
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Jiang, Fan. "New ruthenium and iridium catalysts for transformations involving hydroden transfer." Thesis, Rennes 1, 2014. http://www.theses.fr/2014REN1S170.
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Les activités catalytiques de complexes du ruthénium et de l'iridium ont été examinées dans trois thématiques. De nouvelles phosphines chirales bifonctionnelles à groupement acide et les complexes métalliques correspondants ont été préparés. Nous avons montré que le nouveau ligand (S)-Sulfo-binepine est très efficace pour l'hydrogénation énantiosélective de cétones aromatiques catalysée par le ruthénium et l'hydrogénation énantiosélective de cétiminesaromatiques en présence de catalyseurs de l'iridium. Sur la base d'études mécanistiques, un mécanisme de sphère externe a été proposé pour l'hydrogénation de cétones. Dans le cas de l'hydrogénation de cétimines, les intermédiaires-clés ont été obtenus, ce qui a permis de proposer deux chemins réactionnels compétitifs pour expliquer les effets sur l'énantiosélectivité. Les fonctionnalisations d'amines cycliques sur l'atome d'azote et les carbones en α et β de l'hétéroatome ont été réalisées grâce à des processus de transfert d'hydrogène assistés par des catalyseurs du ruthénium et l'iridium à ligand phosphinesulfonateIn this doctoral thesis, the catalytic activities of new ruthenium and iridium complexes have been examined in three major topics. New chiral phosphine-containing acidic bifunctional ligands and correspondingmetalcomplexes have been prepared. (S)-Sulfo-binepine was shown to be a very efficient novel ligand for ruthenium-catalyzed enantioselective hydrogenation of aryl ketones and iridium-catalyzed enantioselective hydrogenation of arylketimines. Based on mechanistic studies, outer-sphere mechanism was proposed for ketone hydrogenation. For ketimine hydrogenation, the key intermediate and resting species have been obtained, allowing the proposal of two competitive reaction pathways to explain the effects on enantioselectivity. N- and(α,β)-C-functionalization of cyclic amines have been achieved via borrowing hydrogen processes assisted by ruthenium and iridium phosphinesulfonate catalysts
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Le, Trang X. "Oxidation addition of H-H bonds to iridium : developing novel active water soluble catalysts for hydrogenation of unsaturates /." Diss., This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-09232008-144717/.
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Wright, Christopher. "Supported tungsten imido and iridium pincer catalysts towards tandem hydrocarbon upgrading." Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:9ab35e6d-903d-4eeb-9d33-3c8e637aba97.
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The principle aims of this thesis have been to develop well-defined heterogeneous catalysts for potential applications in tandem hydrocarbon upgrading. Catalysts for olefin oligomerisation and metathesis of &alpsha;-olefins and transfer hydrogenation of alkanes based on tungsten mono-imido and PCP pincer iridium complexes have been synthesised and immobilised on solid supports. The reactivity of the immobilised catalysts has been tested and compared with the precursor complexes. Co-immobilisation of the two complexes on the same support has been undertaken. Chapter One provides a background to the olefin metathesis reaction and the development of highly active tungsten mono-imido and ruthenium alkylidene complexes. A summary of the implementation of the olefin oligomerisation reaction by industry and the development of highly active systems based on group 6 metals is discussed, along with a mechanistic discussion. The SOMC grafting procedure is considered and the immobilisation of catalysts for alkane and olefin metathesis and oligomerisation discussed; with focus on support materials: silica, sMAO and AMO-LDHs. Finally, tandem catalysis and its use in hydrocarbon upgrading and copolymerisation are presented. Chapter Two details the synthesis of W(NR)Cl4(THF) complexes and their conversion to W(NR)Me3Cl complexes employing TMA. The products are characterised by single crystal X-ray diffraction, NMR and FTIR spectroscopy. W(NR)Me3Cl complexes are shown to be active for the selective dimerisation of ethylene to 1-butene. Attempted formation of possible intermediates in the reaction is presented, and efforts to form mimics for silica supported species are also discussed. Chapter Three describes the preparation of AMO-LDHs for use as catalyst supports. The effect on the surface hydroxyl content and structural properties of these materials by thermally treating them under vacuum is analysed. Their capability to act as supports for ethylene polymerisation after impregnation with MAO and (nBuCp)2ZrCl2 is described. Chapter Four investigates the immobilisation and characterisation of synthesised tungsten mono-imido complexes on sMAO, AMO-LDHs and silica, utilising SSNMR, FTIR and X-ray absorption spectroscopy. The reactivity of the grafted complexes towards ethylene oligomerisation is discussed. For the immobilised species effects of varying the imido ligand, temperature and solvent medium are reported. Attempts to immobilise ruthenium carbene complexes on AMO-LDHs and sMAO is detailed. Chapter Five gives an account of the immobilisation of Ir(tBuPCP)HCl on sMAO which is characterised by SSNMR and FTIR spectroscopy. Molecular analogues of the supported species are synthesised and reactivity for the hydrogenation of ethylene compared. Transfer hydrogenation reaction with sMAO-Ir(tBuPCP)HCl and COA or ethane with TBE as a sacrificial H2 acceptor are discussed. Finally, co-immobilisation of W{N(2,6-F-C6H3)}Cl4(THF) and Ir(tBuPCP)HCl on sMAO was carried out and the solid characterised by SSNMR spectroscopy. Chapter Six provides experimental details and characterising data for the preceding chapters. An Appendices with crystallographic data, and characterising spectra for each chapter is provided, while the Electronic Appendix contains a combined CIF and checkcif for all the molecular structures presented.
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Theodoulou, Louise. "Supported platinum and iridium catalysts for the selective hydrogenation of cinnamaldehyde." Thesis, University of Reading, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343323.
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Bedford, Robin Bruce. "Group 9 metal catalysts for the homogeneous hydrogenation of carbon-nitrogen double bonds." Thesis, University of Sussex, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240524.
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Courtois, Julien. "Iridium-based bimetallic alloy catalysts for the ethanol oxidation reaction for fuel cells modeled by density functional theory." Digital WPI, 2013. https://digitalcommons.wpi.edu/etd-theses/295.
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Current ethanol oxidation catalysts in direct ethanol fuel cells (typically platinum-based) suffer from low conversion and are susceptible to CO poisoning. Therefore we determined to find viable alternative catalysts for ethanol oxidation based on iridium using density functional theory to model bimetallic alloy (111) surfaces. Iridium was alloyed with another transition metals M in an overlayer (one layer of metal M on top of bulk iridium) or subsurface configuration (M is inserted under the first layer of iridium). Complete oxidation of ethanol is limited by the breaking of strong C-C bonds, so any catalyst must lower the barriers for C-C bond breaking. We modeled the reaction CH+CO →CHCO.Segregation energies were calculated and the subsurface configuration was the most stable configuration in the vast majority of alloy cases. CO adsorption was also studied and a lower CO adsorption energy was found in many alloy cases compared to pure Pt (, providing encouraging results about the possibility of reducing CO poisoning. Activation energies were lowered for the vast majority of the alloys used in an underlayer structure, reinforcing our interest in the underlayer structures or “subsurfaceâ€� alloys. Finally, we found, based on the CO adsorption energies, activation energies of the C-C breakage reaction, and metal cost, three important catalyst descriptors, a number of promising catalysts for the ethanol oxidation reaction. The most interesting alloys all adopted the underlayer structure Ir/M/Ir. With M = Ta, Hf, Nb, V, Zr, they demonstrated enhanced reactivity and high CO tolerance, having the advantage of reducing the cost of the catalyst, potentially substituting expensive platinum group metals by more affordable components.
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Li, Jia-Qi. "Studies of Hydrogenations and Isomerizations of Olefins and Alkylations of Amines Using Iridium Catalysts." Doctoral thesis, Uppsala universitet, Syntetisk organisk kemi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-182647.
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This thesis describes three types of reactions that were carried out using iridium catalysts. The first type is the iridium-catalyzed asymmetric hydrogenation of olefins. In paper I, the preparation of a new type of bicyclic thiazole-phosphine based iridium complex was described. The new catalysts have displayed high activity and enantioselectivity in the asymmetric hydrogenation of unfunctionalized olefins. Papers II and III focus on the expansion of the substrate scope for the iridium catalyzed asymmetric hydrogenation in which a number of heterocyclic olefins were evaluated. In paper IV, the enantioselective asymmetric hydrogenation of α, β-unsaturated esters was described. The chiral products bearing tertiary stereogenic centers obtained by hydrogenation have great synthetic value and have been used in the synthesis of pharmaceuticals as well as in the total synthesis of natural products. The second type is the asymmetric isomerization of allylic alcohols. In paper V, both cis and trans primary allylic alcohols were isomerized to the corresponding β-chiral aldehydes in high enantioselectivities by an N,P-chelating iridium complex. The third type is the selective mono-N-alkylation of amines with alcohols. In paper VI, a phosphine/NHC based iridium catalyst was synthesized and applied in the alkylation of amines. It is the first time that this type of transformation is carried out at room temperature.
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Diebolt, Olivier. "N-heterocyclic carbene ligands in palladium and iridium organometallic chemistry." Thesis, University of St Andrews, 2010. http://hdl.handle.net/10023/2126.
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The use of ligand in transition-metal catalysed reactions has had a considerable impact. The present manuscript aims at showing the influence of ligands in the palladium catalysed Suzuki-Miyaura cross-coupling reaction. In chapter one, the mechanism of this reaction will be described based on the numerous contribution published in the literature. It will be shown that the electronic and steric properties of the ligands have a huge repercussion on the catalytic activity of the metal. In the second chapter, the electronic and steric properties of the widely used Buchwald-phosphine ligand will be investigated. For this purpose, bis-carbonyl iridium(I) complexes were synthesized and their characterization allowed determining their TEP (Tolman electronic parameter) and their buried volume %V[subscript(bur)]. Then three next chapters of this thesis will focus on the syntheses and characterizations of new palladium complexes bearing N-heterocyclic carbenes (NHC). Their design was made in a view to obtain high activity in cross coupling reaction, particularly in the Suzuki-Miyaura cross coupling. Their activation under the catalytic conditions leads to the formation of palladium(0) species that can be mono- or bis-ligated. The influence of the ligand on the catalyst activity will be discussed. A palladium(II) precatalyst leading to mono-ligated active species will be described. Its activity in cross-coupling is very good, since activated and non-activated aryl chlorides could be coupled with aryl boronic acids at room temperature using low catalyst loadings. Unfortunately, the catalyst activity decreased with temperature. This result showed the fragility of the mono-ligated active species. In a view to obtain more robust catalysts that can perform high turnover numbers, new palladium(II) precatalysts bearing two ancillary ligands were developed. Mixed systems NHC- phosphites and NHC-phosphines are described. NHC-phosphites precatalysts displayed very good activity, but the phosphites are unfortunately sensitive to reaction conditions, limiting their role of active species shield. NHC-phosphine bearing complexes were highly active and could perform up to 10,000 turnovers with unactivated aryl chlorides. Very interestingly, these catalysts were also able to couple benzylchlorides and allyl chlorides with a wide range of boronic acids at very low catalyst loadings. These reactions had also the great advantage to proceed in aqueous solvents at very high substrate concentration. The activation mechanism of these complexes was investigated. Dichloropalladium(II) complexes were reduced under the catalytic conditions to lead palladium(0) species. Therein, it is shown that this reduction step was rate-determining in catalysis. Some palladium(0) intermediates xxiv were synthesized and showed good to excellent activities at low temperature under the exact same conditions. They displayed high reactivity towards oxygen and moisture and have to be handled under inert atmosphere. A particular complex had the ability to react with molecular dioxygen to form a stable peroxo-complex. Interestingly, this complex displayed excellent activity in water under aerobic conditions. This system was of great advantage since the reaction could be set up under air using cheap and user-friendly reagents displaying low toxicity. Moreover, the readily available distilled water used as solvent did not require prior degassing. Symmetrical and unsymmetrical bis-NHC palladium(0) complexes were successfully synthesized. They display excellent activity in the Suzuki-Miyaura cross coupling and turnover frequencies as high as 300 could be obtained at room temperature with unactivated arylchlorides and arylboronic acids. These complexes were also found excellent catalysts for the coupling of benzylchlorides with arylboronic acids. Mechanistic studies showed that no ligand dissociation occurred during the coupling suggesting as bis-ligated active species.
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Wang, Yueming. "Ionic liquids and iridium hydrogen transfer catalysts for the reaction of renewable alcohols." Thesis, Queen's University Belfast, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709855.
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This thesis is about the study of developing novel catalysts and catalytic processes and applying them to convert renewable alcohols produced from biomass into value-added chemicals. It focuses on developing iridium catalysts for hydrogen transfer initiated dehydration of 1,3- propanediol in ionic liquids as solvent and applying functionalized ionic liquids as homo- and heterogeneous catalysts for dehydration of D-sorbitol and rac-1-phenylethanol respectively.
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Ruddlesden, Amy. "Novel neutral iridium catalysts for effective hyperpolarisation and hydrogenation : a synthetic and mechanistic study." Thesis, University of York, 2017. http://etheses.whiterose.ac.uk/18700/.
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Since 2009, when the Signal Amplification By Reversible Exchange (SABRE) process, which transfers polarisation from parahydrogen to substrates in a non-hydrogenative manner, was first published, substantial efforts have been made in method optimisation and catalyst development. This work presents multi-step syntheses and studies on a series of novel neutral bidentate iridium carbene complexes, [Ir(COD)(R-NHC-O)]. The carbene ligands have a pendent phenolate group, incorporating the electron-withdrawing substituents, NO2, COOMe, Cl and H. The reactivity of each complex with substrate and hydrogen has enabled the identification of several intermediates, including dihydride COD complexes, [Ir(H)2(COD)(R-NHC-O)]. COD hydrogenation facilitates the formation of SABRE-active pyridyl dihydride species with structures dependent on the R substituent and solvent used. In DCM, the Ir-O bond is stable and complexes of [Ir(H)2(R-NHC-O)(py)2] form. However, in methanol, when the electron density is increased as R is changed to an H substituent, complete Ir-O bond cleavage occurs to form [Ir(H)2(H-NHC-O)−(py)3]+. When studied with parahydrogen, these complexes act as efficient SABRE catalysts for a variety of substrates in a range of polarity solvents. They undergo the necessary substrate and hydrogen exchange processes, leading to the observation of enhanced NMR signals for pyridine, nicotinamide, nicotine and nicotinaldehyde. A study into the parahydrogenation of phenylacetylene using the NO2-containing catalyst has also been completed. Although it was less reactive than Crabtree’s catalyst it proved more stable due to minimal degradation over time.
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Riley, C. C. A. "Effect of pretreatment of the state and reactivity of alumina-supported platinum-iridium catalysts." Thesis, Imperial College London, 1987. http://hdl.handle.net/10044/1/46303.
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Owens, Philippa Kate. "Iridium complexes as highly active catalysts for hydrogen isotope exchange and hydrogen borrowing processes." Thesis, University of Strathclyde, 2018. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=30297.
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Over the last several decades, the organic chemistry community has become increasingly reliant upon iridium catalysis, with applications reported across a number of research areas. In recent years, the Kerr group has developed a series of iridium complexes, which were found to be excellent catalysts for hydrogen isotope exchange and olefin hydrogenation processes. The work described within this thesis centres upon the expansion of these catalysts’ reactivity in hydrogen isotope exchange, as well as the synthesis and application of a series of novel iridium complexes, designed for use in hydrogen borrowing catalysis. Chapter one focuses on the development of three efficient and selective methods for hydrogen isotope exchange. Iridium(I) catalysts previously developed within the group have been employed in the successful deuteration of N-heterocycles, which represent an important and relatively underexplored class of labelling substrates. The labelling of a large range of indole, pyrrole, and quinoline derivatives is reported, in which the regioselectivity can be controlled through careful choice of N-protecting group. Extensive practical and computational mechanistic investigations offered insight into the mechanism of indole C3 labelling, which is believed to proceed via an iridium–indoline intermediate. In chapter two, the design and synthesis of a series of novel unsymmetrical NHC ligands, functionalised with electron donating substituents, is described. The corresponding neutral iridium NHC/halide complexes were prepared, and the steric and electronic properties of the ligands were investigated using a number of techniques. These novel complexes were then tested in the catalysis of hydrogen borrowing processes. Extensive optimisation led to the development of an efficient method for the room-temperature N-alkylation of anilines. This methodology was also expanded to include the synthesis of N-heterocycles viaintramolecular C–N bond formation, albeit using more forcing conditions. Lastly, a small series of chiral NHC ligands was designed, and their corresponding iridium complexes prepared and used in a preliminary screening of asymmetric hydrogen borrowing.
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Rifat, Adem. "Exo-closo carborane complexes of rhodium and iridium : synthesis and evaluation as hydrogenation catalysts." Thesis, University of Bath, 2003. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.425661.
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Romagnoli, Elia. "Iridium-catalyzed asymmetric hydrogenation of N-allyl phthalimides." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/17959/.
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The unprecedented iridium-catalyzed asymmetric hydrogenation of N-allyl phthalimides to afford enantioenriched chiral amines bearing a β-methyl is presented. Recently developed Ir-MaxPHOX are used as catalysts for this enantioselective transformation. The hydrogenation reaction has been studied in detail in order to find the optimal conditions. The mild reaction conditions and the feasibility of the removal of the phthalimido protecting group makes this process easily scalable and of interest for multiple synthetic applications.
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Salomó, i. Prat Ernest. "P-Stereogenic Intermediates and MaxPHOX ligands. Iridium Catalyzed Asymmetric Hydrogenations." Doctoral thesis, Universitat de Barcelona, 2018. http://hdl.handle.net/10803/663829.
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Asymmetric hydrogenation of double bonds by means of organometallic catalysis is a powerful tool for organic synthesis; it is an efficient and simple method to produce valued chiral compounds. Among the many different existing ligands, phosphorous ones have proven very useful for these procedures. The ligand plays a vital role in the catalysis, as the ligand’s chirality can transferred to the product. There is a wide range of P-based chiral ligands and can be classified in 3 groups depending on where the chirality lies; on the P unit, on the C-backbone or on both the P unit and the C-backbone.
In the first section of the present PhD thesis we have studied new methodologies for the synthesis of compounds with chiral phosphorous. We developed the reduction of an important chiral phosphinous acid developed in our group to the corresponding secondary phosphine borane by means of a completely enantioselective SN2@P. This phosphine is a known compound, useful to access important P-stereogenic ligands. We have also designed a derivative of the aforementioned phosphinous acid, which is much more stable. This derivative maintains all the reactivity of the phosphinous acid in the SN2@P reaction with nucleophiles.
In the second section of the present PhD thesis we were able to produce a small family of P-stereogenic Ir-MaxPHOX catalysts. We have applied this library to the reduction of different interesting substrates from a pharmaceutical or agrochemical point of view. We hydrogenated different challenging imines (N-aryl imines and N-alkyl imines) to the corresponding amines with excellent enantioselectivities. We also reduced cyclic enamides (α- and β-enamides) to the corresponding amides. In this later case, the control over the ee was complete. These are the best results reported in the literature so far.La hidrogenación asimétrica de dobles enlaces mediante catálisis es un método eficiente y simple para producir valiosos compuestos quirales. De entre los distintos ligandos existentes, los de fósforo han demostrado ser muy útiles en estos procesos. El ligando juega un rol vital en la catálisis debido a que la quiralidad en este se puede transmitir al al producto. Hay un amplio rango de ligandos que contienen fósforo y se pueden clasificar básicamente en 3 grupos según donde reside la quiralidad; en el esqueleto de carbono, en el átomo de P o bien en ambos. En la primera parte de la presente tesis doctoral hemos estudiado nuevas metodologías para la síntesis de moléculas con P* (fósforo quiral). Desarrollamos la reducción de un importante ácido fosfinoso quiral desarrollado por nuestro grupo a la correspondiente fosfina secundaria boronada mediante una reacción SN2@P completamente enantioselectiva. La fosfina obtenida es un compuesto conocido que se usa para sintetizar diferentes ligandos P-stereogenicos. También sintetizamos un derivado del ya antes mencionado ácido fosfinoso, el cual es mucho más estable. Demostramos que este derivado mantiene toda la reactividad en la reacción SN2@P con nucleófilos respeto al ácido fosfinoso. Durante la segunda parte de esta tesis sintetizamos una pequeña familia de catalizadores Ir-MaxPHOX y los usamos para hidrogenar asimétricamente distintos compuestos de interés para la industria farmacéutica y agroquímica. Hemos hidrogenado distintas iminas (N-aril y N-alquil iminas) a las correspondientes aminas con excelentes enantioselectividades. Conseguimos también reducir enamidas cíclicas (α- y β-enamidas) a las correspondientes amidas. Para este último caso, el control sobre el ee fue completo, consiguiendo así los mejores resultados para estos sustratos hasta la fecha.
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Chan, Ka Wang. "Synthesis and reactivity of iridium, rhodium and ruthenium alkyl complexes containing 2,2'-bipyridine /." View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?CHEM%202008%20CHANK.
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Sau, Yiu Keung. "Part I, Synthesis and reactivity of 2,2'-bipyridine-supported iridium alkyl compounds ; Part II, Metal complexes with chiral phosphine oxide and sulfoxide ligands /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?CHEM%202005%20SAU.
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Ketcham, Ryan R. "DEVELOPMENT OF NOVEL ELECTROPHILIC RUTHENIUM(II) AND IRIDIUM(III) COMPLEXES AND THEIR APPLICATIONS AS HOMOGENEOUS CATALYSTS." UKnowledge, 2011. http://uknowledge.uky.edu/gradschool_theses/100.
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Our aim was to develop the synthetic potential and reaction chemistry of Ir3+ and Ru2+ electrophiles by preparing well-characterized complexes whose properties are controllable by modification of the ancillary ligand environment Specifically, we prepared a series of ruthenium complexes to serve as selective hydrogenation and hydrogenolysis catalysts of furan derivatives. We also expanded the synthesis of electrophilic Ir3+ di-thiolate complexes. These types of compounds could eventually serve as catalysts precursors for the addition of weak nucleophiles to alkynes and nitriles.
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Hernandez, Sanchez Dalyanne N. "Synthesis of Chiral Salen-type Ligands for Iridium Catalysts Used in C-H Bond Insertion Reactions." Kent State University Honors College / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ksuhonors1620475657966529.
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Shen, Xiaodong [Verfasser], and Eric [Akademischer Betreuer] Meggers. "Octahedral Chiral-at-Metal Iridium and Rhodium Complexes as Versatile Asymmetric Catalysts / Xiaodong Shen. Betreuer: Eric Meggers." Marburg : Philipps-Universität Marburg, 2016. http://d-nb.info/1102354457/34.
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Idziak, Christopher. "The application of density functional theory for understanding organic reactivity : nitration, super electrophiles, iridium catalysts, methanol formation." Thesis, University of Strathclyde, 2013. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=23622.
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In this thesis, the ability of modern density functional theory to model organic reaction mechanisms is examined. The insights that can be obtained from computational chemistry range from the very nature of the mechanisms - the fundamental forces that drive the reaction forward - through to the role of the environment and the properties of the resulting molecules. However, the importance of these insights is most readily displayed through their application to challenging experimental problems. Therefore, the projects that are described in this work are all associated with experimental studies that are in a position to utilise the insights obtained. In the study on the nitration of 6-chloropyrimidine-4(3H)-one (Chapter 3), it was shown that the inductive effect can be employed in some instances to provide a mechanistic explanation for reactivity. This was observed to be relevant where there is a moiety within the molecule, which either withdraws or donates electronic density from or to this group. In the study on the superelectrophilic activation in amidine dications (Chapter 4), it was shown that relative energetics with respect to formation of reactant/product complexes and transition states can be influenced by the presence or absence of associated counterions. In the study on the use of iridium based catalysts for hydrogen isotope exchange (Chapter 5) the role of solvent molecules in affecting the reactivity was assessed. This study led to the rationalization and selection of a preferred and beneficial solvent for carrying out these reactions. In the formation of methanol from CO and CO2 (Chapter 6) an explanation in terms of relative energetic changes of a series of steps in a novel route to Methanol formation has been reported. It has been shown that the relative energetics of these set of reactions are within a satisfactory range for the process to proceed as represented experimentally.
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Vuong, Khuong Quoc Chemistry Faculty of Science UNSW. "Metal complex catalysed C-X (X = S, O and N) bond formation." Awarded by:University of New South Wales. Chemistry, 2006. http://handle.unsw.edu.au/1959.4/23015.
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This thesis describes the catalysed addition of X-H bonds (X = S, O and N) to alkynes using a range of novel rhodium(I) and iridium(I) complexes containing hybrid bidentate phosphine-pyrazolyl, phosphine-imidazolyl and phosphine-N heterocyclic carbene (NHC) donor ligands. The synthesis of novel bidentate phosphine-pyrazolyl, phosphine-imidazolyl (P-N) and phosphine-NHC (PC) donor ligands and their cationic and neutral rhodium(I) and iridium(I) complexes [M(P N)(COD)]BPh4, [M(PC)(COD)]BPh4, [Ir(P-N)(CO)2]BPh4 and [M(P-N)(CO)Cl] were successfully performed. An unusual five coordinate iridium complex with phosphine-NHC ligands [Ir(PC)(COD)(CO)]BPh4 was also obtained. Seventeen single crystal X-ray structures of these new complexes were determined. A range of these novel rhodium and iridium complexes were effective as catalysts for the addition of thiophenol to a variety of alkynes. Iridium complexes were more effective than rhodium analogues. Cationic complexes were more effective than neutral complexes. Complexes with hybrid phosphine-nitrogen donor were more effective than complexes containing bidentate nitrogen donor ligands. An atom-economical, efficient method for the synthesis of cyclic acetals and bicyclic O,O-acetals was successfully developed based on the catalysed hydroalkoxylation. Readily prepared terminal and non-terminal alkyne diols were cyclised into bicyclic O,O-acetals in quantitative conversions in most cases. The efficiency of a range of rhodium and iridium complexes containing bidentate P-N and PC donor ligands as catalysts for the cyclisation of 4-pentyn-1-amine to 2-methyl-1-pyrroline varied significantly. The cationic iridium complexes with the bidentate phosphine-pyrazolyl ligands, [Ir(R2PyP)(COD)]BPh4 (2.39-2.42) were extremely efficient as catalysts for this transformation. Increasing the size of the substituent on or adjacent to the donor led to improvement in catalytic activity of the corresponding metal complexes. The mechanism of the catalysed hydroalkoxylation was proposed to proceed by the initial activation of the alkyne via ?? coordination to the metal centre. The ?? binding of both aliphatic and aromatic alkynes to [Ir(PyP)(CO)2]BPh4 (2.44) was observed by low temperature NMR and no reaction between 2.44 and alcohols was observed. In contrast, the facility in which thiol and amine oxidatively added to 2.44 led the proposal that in the hydrothiolation and hydroamination reaction, the catalytic cycle commences with the activation of the X-H bond (X = S, N) by an oxidative addition process.
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Hedberg, Christian. "Design, Synthesis, Mechanistic Rationalization and Application of Asymmetric Transition-Metal Catalysts." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-5740.
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Müller, Marc-André [Verfasser]. "Study of Chiral Iridium N,P Ligand Complexes as Catalysts for the Asymmetric Hydrogenation of Different Substrate Classes / Marc-André Müller." München : Verlag Dr. Hut, 2014. http://d-nb.info/1060587750/34.
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Pafford, Robert J. "Synthesis and hydrogenation of iridium complexes with bidentate and water-soluble phosphine ligands : developing novel water-soluble catalysts for hydrogenation of unsaturates /." Thesis, This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-11242009-020347/.
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Hajar, Yasmine. "Effect of Electrochemical Promotion and Metal-Support Interaction on Catalytic Performance of Nano-catalysts." Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/39701.
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In heterogeneous catalysis, promoting the activity of the catalytic metals is long known as an important method to make a process more efficient and viable. Noble metals have been promoted classically by a chemical coverage of an ionic solution on the surface of the catalyst or using inert support, e.g., silica or alumina, allowing an increase of the dispersion of the catalyst. Therefore, new methods of promotion needed to be better explored to improve the efficiency of metal and metal oxide catalysts. One way of enhancing the catalyst’s activity is to disperse the noble metal at the nanoscale using an active type of support that is ion-conducting. Not only lattice ions can be exchanged with the surface of the nanoparticles but it can also engage in the oxidation reaction on the surface, resulting in what is known as metal-support interaction (MSI). Another method of improving the catalytic activity is to polarize the catalyst, allowing ions to migrate from a solid electrolyte to the gas-exposed surface, in a phenomenon known as electrochemical promotion of catalysis (EPOC). The change in the ions concentration on the surface would change the adsorption energy of the gaseous reactants and enhance or supress the catalytic rate.
In this thesis, the effect of supporting nanoparticles of noble and non-noble metal (oxides) (Pt, Ru, Ir, Ni) was studied for the case of ionic and ionic-electronic conducting supports (CeO2, TiO2, YSZ). The enhancement in their catalytic rate was found and correlated to an electrochemical property, the exchange current density. Then, using isotopically-labeled oxygen, the oxygen exchange ability of the conductive oxides was evaluated when supporting Ir and Ru nanoparticles and correlated with the results from C3H8 isotopic oxidation reaction, which showed the extent of involvement of oxygen from the support as carried by the isotopically-labeled CO2 produced.
Following this, electrochemical promotion of catalysis experiments were performed for different reactant/catalyst systems (C2H4 - Pt, Ru; C3H8 - Pt; CH4 - Pd, Ni9Pd). In the first system, the main outcome was the functional equivalence found for the MSI and EPOC effect in promoting the catalysts as experiments were performed at different temperatures, reactants partial pressures and polarization values. In the case of C3H8/Pt, the novel dispersion of Pt on an intermediate supporting layer (LSM/GDC) was found as a feasible method to obtain long stability of the catalyst while electrochemically promoting the rate of reaction. For CH4 oxidation, the polarization of the Pd nanoparticles showed continuous oxidation of the bulk of the catalyst resulting in a continuous increase of the catalytic rate. The Ni9Pd synthesized in a way to form a core/double-shell layer of Ni/Pd resulted in an enhanced catalytic rate and enhanced stability compared to stand-alone Pd.
And lastly, to comprehend the ions’ effect in the electrochemical promotion and the non-Faradaic nature of the phenomena, density-functional theory (DFT) modeling was used to demonstrate the increase of the heat of adsorption of reactants depending on their electronegative/positive nature.
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Zuo, Wei [Verfasser], and Eric [Akademischer Betreuer] Meggers. "Chiral-at-Metal Iridium(III) and Rhodium(III) Lewis Acid Catalysts for the α-Functionalization of 2-Acyl Imidazoles / Wei Zuo ; Betreuer: Eric Meggers." Marburg : Philipps-Universität Marburg, 2018. http://d-nb.info/1156461731/34.
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Geiger, Simon [Verfasser], Karl J. J. [Gutachter] Mayrhofer, and Wolfgang [Gutachter] Schuhmann. "Stability investigations of iridium-based catalysts towards acidic water splitting / Simon Geiger ; Gutachter: Karl J. J. Mayrhofer, Wolfgang Schuhmann ; Fakultät für Chemie und Biochemie." Bochum : Ruhr-Universität Bochum, 2018. http://d-nb.info/1154307751/34.
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Jofre, Jorge Benedito Freire. "Catalisadores de Ir-Ru/Al2O3 e Ru/Al2O3 aplicados em sistemas propulsores." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/97/97137/tde-03102012-112753/.
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Catalisadores de Ir/Al2O3, Ir-Ru/ Al2O3 e Ru/ Al2O3 com teores metálicos próximos a 30% em peso, foram preparados em vinte etapas de impregnação utilizando-se uma alumina sintetizada no LCP/INPE como suporte. Os catalisadores de Ir e Ir-Ru foram preparados a partir de soluções contendo precursores metálicos clorados pelo método de impregnação incipiente. Os catalisadores de Ru foram preparados a partir de dois precursores metálicos: um clorado e um precursor orgânico. Neste caso, o catalisador originado do precursor clorado foi preparado por impregnação incipiente, enquanto que o catalisador originado do precursor orgânico foi preparado pelo método de impregnação por excesso de volume. Todos os catalisadores foram caracterizados antes e depois dos testes em micropropulsor pelas técnicas: absorção atômica, para a determinação do teor metálico; fisissorção de nitrogênio, para determinações de área específica e distribuição do volume de mesoporos; quimissorção de hidrogênio e MET, para determinações da dispersão e do diâmetro médio das partículas metálicas (dQH e dMET). Os catalisadores foram testados na reação de decomposição de hidrazina em micropropulsor e comparados com o catalisador comercial Shell 405. Os resultados mostraram que os catalisadores contendo Ir apresentaram desempenho similar ao catalisador comercial e que os catalisadores de Ru não devem ser usados em partidas frias.Ir/Al2O3, Ir-Ru/ Al2O3 and Ru/ Al2O3 catalysts with metallic loading of c. a. 30 %wt., were prepared in twenty impregnation steps using an alumina synthesized at LCP/INPE as support. The Ir and Ir-Ru catalysts were prepared from metallic chloride precursors solutions by incipient impregnation method. The Ru catalysts were prepared from two metallic different precursors: a chloride precursor and an organic precursor. In this case, the catalyst originated from the chloride precursor was prepared by the incipient impregnation method, while the catalyst originated from the organic precursor was prepared by volume excess impregnation method. All the catalysts were characterized before and after the microthruster tests by the following techniques: atomic absorption, for metallic content determination; nitrogen physiosorption, for specific area and mesoporous volume distribution; hydrogen chemisorption and TEM, for dispersion and metallic particles average diameter (dQH and dMET ). The catalysts were tested by the hydrazine decomposition reaction in microthruster and compared with commercial catalyst Shell 405. The results showed that the performance of Ir catalysts are similar to the commercial ones and the Ru catalysts should not be used in cold startups.
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Sousa, Ednaldo Conceição. "Catalisadores de irídio suportados em aluminas modificadas com índio para o tratamento do gás de combustão emitido de unidades de FCC- abatimento de NOx." reponame:Repositório Institucional da UFBA, 2012. http://www.repositorio.ufba.br/ri/handle/ri/11593.
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CNPq
A emissão de poluentes atmosféricos, tais como, monóxido de carbono (CO), óxidos de enxofre (SOX) e óxidos de nitrogênio (NOX) é, atualmente, um dos maiores problemas encontrados em processos industriais. O óxido nítrico (NO) representa cerca de 95% de toda emissão de NOX para a atmosfera. Uma das principais fontes de emissão de NOX são as unidades de regeneração de catalisadores de craqueamento catalítico em leito fluidizado (FCC). Nesse trabalho, foram utilizados catalisadores de irídio suportados em aluminas (0,1-1,0%/Al2O3) e em aluminas modificadas com índio (0,1%Ir/InxAl2-xO3). Os catalisadores foram preparados pelo método de impregnação úmida, sendo que para os suportes foi utilizado o método da combustão. Os materiais obtidos foram avaliados cataliticamente na redução de NO com CO na presença de O2, H2O e SO2. Todos os catalisadores mostraram-se ativos e hidrotermicamente estáveis em toda região de temperatura investigada (250 – 600°C) operando sobre alta velocidade espacial. O s catalisadores que não continham In em suas formulações apresentaram uma pequena desativação na presença de SO2, enquanto que, para os que possuíam In a presença de SO2 no meio reacional aumentou a atividade dos catalisadores, comprovando o efeito promotor deste metal. Catalisadores com baixo teor de Ir mostraram-se mais ativos do que os com altos teores. A influência do O2 no meio reacional também foi investigada, onde foi verificada uma forte dependência da presença do mesmo para a atividade do catalisador. Na ausência de O2, os catalisadores investigados tiveram uma significativa redução da atividade tanto na redução de NO quanto na conversão de CO. Avaliando o efeito do pré-tratamento, verificou-se que as amostra préreduzidas tiveram um maior desempenho no teste catalítico do que as pré-oxidadas. Sugerindo assim, que o sítio ativo para a redução de NO com CO sobre catalisadores de irídio é o Ir0. Todos os catalisadores demonstraram alta conversão de CO e seletividade a CO2.
Salvador
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Pfeifer, Verena [Verfasser], Robert [Akademischer Betreuer] Schlögl, Robert [Gutachter] Schlögl, Peter [Gutachter] Strasser, and Hans-Peter [Gutachter] Steinrück. "Identification of reactive oxygen species in iridium-based OER catalysts by in situ photoemission and absorption spectroscopy / Verena Pfeifer ; Gutachter: Robert Schlögl, Peter Strasser, Hans-Peter Steinrück ; Betreuer: Robert Schlögl." Berlin : Technische Universität Berlin, 2017. http://d-nb.info/1156015952/34.
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Závodný, Adam. "Katalytické systémy založené na jednotlivých atomech." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-241710.
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Single atom catalysts are prospective class of materials, which holds promises to reach the ultimate limit of improvement in catalyst performance, selectivity, lifetime and cost reduction. The ability to efficiently capture the adsorbates at the active sites is the key prerequisite for catalytic transformation to the products. In this respect, our experimental study aims to describe the interaction of gas molecules (H2O, CO, O2 and NO) with single metal atoms (Rh, Ir, Cu) on the magnetite surface employing scanning tunneling microscopy.
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Cadu, Alban. "Iridium Catalysed Asymmetric Hydrogenation of Pyridines." Licentiate thesis, Uppsala universitet, Syntetisk organisk kemi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-212413.
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This thesis presents the hydrogenation of substituted pyridines using N,P-ligated iridium catalystsin homogeneous media. These iridium catalysts were developed within this research group in thepast decade. This method of hydrogenation is highly stereoselective, and in several cases good to excellent ees were obtained.The hydrogenation of substituted pyridines was studied: by screening for the catalyst giving thehighest conversion and ee, by optimising the reaction conditions and by attempting to improve existingcatalysts. New substrates were synthesised for this process, in particular alkyl substituted Nprotectedpyridines. Their reduction provided chiral piperidines, which could be used as chiralbuilding blocks once deprotected.
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Ellis, Richard D. "Reductive amination catalysed by iridium complexes." Thesis, University of Sussex, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341064.
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Simons, Keith Edward. "Asymmetric hydrogenation catalysed by platinum and iridium." Thesis, University of Hull, 1994. http://hydra.hull.ac.uk/resources/hull:6909.
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The enantioselective hydrogenation of α-ketoesters over supported platinum metal catalysts which have been modified by chiral molecules has been studied. The aim of this thesis was (a) to gain a greater understanding of the kinetics of asymmetric hydrogenation of methyl pyruvate (MeCOCOOMe) to methyl lactate (MeCH(OH)COOMe) over cinchonidine modified EUROPT-1, (b) to diversify the reaction, by variation of the metal, modifier and reactant and (c) to test and develop a mechanism to explain the reaction by both mathematical and molecular modelling. It was found that only very small quantities of cinchonidine modifier were required to render EUROPT-1, a 6.3 % Pt/silica catalyst, suitable for asymmetric hydrogenation of methyl pyruvate. The plots of the variation of with reaction rate and of optical yield with modifier loadings reached plateau values at a loading of ca. 0.8 mg cinchonidine per 100 mg EUROPT-1. The shape of the curves has been fitted to a mathematical model which gives evidence that the mechanism is a result of a 1: 1 interaction between modifier and reactant. Modification of catalyst by mixtures of cinchonidine and cinchonine, or of quinine and quinidine has been performed and results obtained as to the effect on reaction rate and optical yield. The variation of the latter with the mole fraction of modifier has been fitted to a mathematical model which supports the view that the mechanism is a result of a 1: 1 interaction. It has been discovered that Iridium, especially when supported on calcium carbonate, is an effective catalyst for both racemic and enantioselective hydrogenation of methyl pyruvate. When Ir/CaCO³ was reduced and modified by cinchonidine, hydrogenation of methyl pyruvate at 273 K and 10 bar in ethanol resulted in an optical yield of 39 %. The reaction is approximately zero order in reactant and first order in hydrogen, being first order overall. The apparent activation energy was 22 ±2 kJ mol-1. The unmodified reaction proceeded at a very fast rate with an apparent activation energy of 11 ±2 kJ mol- 1. The enhanced rate was explained in terms of stabilisation of the halfhydrogenated state by the carbonate support. Rhodium, Osmium and Rhenium were found not to be effective for asymmetric hydrogenation, which in the case of rhodium is contrary to the literature. Diversification of the modifier was found to be possible, the best alternative being by the use of 10,1 1-dihydroquinine 4-methyl-2-quinoyl ether which gave an optical yield of 22 %. The amino acids tryptophan and histidine were found to give poor but reproducible enantiomeric excesses. Ephedrines and benzyl pyrrolidine methanol were found not to be effective modifiers which is contrary to the literature. A molecular modelling study resulted in a new proposal for the asymmetric hydrogenation site which explained the mechanism in terms of a 1:1 interaction between modifier and reactant at the catalyst surface. The proposal successfully accounts for the observed enantioselectivity in terms of steric hindrance to the unwanted product. The proposed mechanism is in agreement with experimental data in the literature.
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Harrisson, Peter. "Developing and understanding iridium-catalysed arene borylation." Thesis, Durham University, 2011. http://etheses.dur.ac.uk/1409/.
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Iridium catalysed C-H borylation has moved from an interesting observation to an efficient catalytic reaction. This work has developed and improved upon some of the key issues associated with the methodology. The one-pot conversion of aryl boronates, generated by C-H borylation, to other functionality has been one area of interest. However, reactions typically require a change in reaction solvent to make this possible. This thesis describes a one-pot, single solvent C-H borylation/Suzuki-Miyaura cross-coupling sequence. The key to this transformation is the use of methyl tert-butyl ether (MTBE). This procedure allows efficient synthesis of biaryls by initial C-H borylation of aromatic substrates followed by addition of water, subsequent reagents and aryl halide to complete the Suzuki-Miyaura cross-coupling without the need for change in reaction solvent. Another issue associated with the C-H borylation reaction is the extended reaction times required for some substrates. This issue was tackled by development of a microwave accelerated C-H borylation reaction. Microwave reactions are conducted at the same temperature as standard heated reactions with accelerations of 2 - 24 times affording comparable product yields. Typically reaction times were reduced from hours to minutes. A microwave accelerated one-pot, single solvent C-H borylation/Suzuki-Miyaura cross-coupling sequence allowed synthesis of biaryls from arene plus aryl halides in reaction times of minutes. Subsequent work focussed on the borylation of novel substrates classes, in particular quinolines. The borylation of substituted quinolines highlighted interesting electronic selectivity of the reaction. The site of borylation can be directed by changing the nature of the substituent on the ring. DFT calculations have been conducted to gain understanding into the causes of selectivity. A link between C-H acidity, calculated by DFT methods, and the borylation site was observed. Preliminary studies into the borylation of azaindoles are discussed. Studies towards a procedure to convert aryl boronates to trifluoromethyl groups are also been introduced.
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Bonneau, Mickaële. "Synthesis and Luminescence Properties of New Platinum and Iridium Complexes." Thesis, Rennes 1, 2015. http://www.theses.fr/2015REN1S114/document.
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Les travaux de cette thèse portent sur la synthèse et les études en photoluminescence de nouveaux complexes de métaux de transitions (Ir(III), Pt(II), Pd(II)). Le principal objectif est d’obtenir de nouveaux matériaux phosphorescents pour des applications telles que les diodes organiques électroluminescentes (OLEDs) ou la bio-imagerie. L’incorporation de chromophores tels que le pyrene et le naphtalimide au complexe fac-Ir(thpy)3 sera tout d’abord présenté. La synthèse par activation C–H de ces nouveaux complexes sera également étudié. De nouveaux complexes organométalliques ultra-rigides seront ensuite développés. La synthèse ainsi que les analyses en photoluminescence de complexes tetradentate de platine et de palladium seront ensuite décrits. Enfin, une analyse de nouveaux complexes d’iridium comportant des ligands benzimidazoles (iso)-quinoline et bis-benzimidazole sensibles aux variations de pH sera faiteThe work of this thesis is focused on the synthesis and the photoluminescence studies of new 3 raw transition metal complexes (Ir(III), Pt(II), Pd(II)) . The main objective is to obtain new phosphorescent materials for applications such as organic light emitting diodes (OLEDs) and bio- imaging. The incorporation of chromophores such as pyrene and naphthalimide into fac-Ir-(thpy)3 complex will first be presented. The synthesis, by C–H activation, of the new complex will also be studied. New ultra-rigid organometallic complexes will then be developed. The synthesis and the photoluminescence analysis of these tetradentate platinum and palladium complexes will be described. Finally, a study of new iridium complexes incorporating benzimidazoles (iso)-quinoline and bis-benzimidazole ligands sensitive to pH variations will be made
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Codolà, Duch Zoel. "Iron and iridium molecular complex for water oxidation catalysis." Doctoral thesis, Universitat de Girona, 2014. http://hdl.handle.net/10803/276172.
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Harness light from the sun is one of the 21st century’s major goals towards the substitution of fossil fuels for a renewable source of energy. Sustainable production of highly energetic molecules using sunlight as energy source can provide a recyclable fuel round the clock. In this regard, hydrogen from water is envisioned as an ideal cofactor as this energetic store. Viable production of solar fuels will require the use of earth-abundant based catalysts with high activity and efficiency. Long ago, Nature figured out how to take advantage of the sunlight by converting solar energy into chemical bonds, through water and carbon dioxide. This process has been perfected during millions of years and the development of an artificial system to replicate the natural photosynthesis is extremely challenging. Towards the design of these energy conversion schemes based on sunlight, CO2 and H2O, a key step is the water oxidation. The water oxidation provides the electrons needed for the production of fuel. An efficient catalyst is required to overcome the uphill energy multi-electron transformation. The main objective of this thesis is the design of artificial compounds that efficiently oxidizes water into O2, protons and electrons, as the first step towards the exploitation of the sunlight. The study of these complexes could contribute with valuable information about the oxidation mechanisms taking place during the photosynthesis. The results obtained in this thesis firstly show that readily available iron and iridium complexes can carry out the water oxidation in an efficient manner. Homogeneous high valent metal species (IrV/VI, FeV) are the responsible of this redox process. Furthermore, the characterization of a novel oxo-bridged iron-cerium complex constitutes the first direct observation of a heterodimetallic core in a synthetic water oxidation catalyst. These species can be construed as the closest structural and functional model for the essential heterodimetallic MnV–O–CaII center involved in the water oxidation in PSII.L’aprofitament de la llum solar com a font d’energia és un dels objectius més prometedors alhora de substituir els combustibles fòssils per una font d’energia renovable. La producció sostenible de molècules energètiques mitjançant la llum del sol pot proporcionar un combustible reciclable durant les 24 hores del dia. En aquest aspecte, l’hidrogen obtingut de l’aigua s’entreveu com un cofactor ideal per aquest emmagatzematge energètic. L’ús de catalitzadors basats en materials abundants i amb una activitat i eficiència elevades seran elements indispensables per a la producció viable de combustibles solars. La natura va ser capaç de trobar un mecanisme per aprofitar l’energia solar convertint-la en enllaços químics mitjançant aigua i diòxid de carboni. Aquest procés ha sigut perfeccionat al llarg de milions d’anys i conseqüentment, el desenvolupament de sistemes artificials capaços d’imitar la fotosíntesi natural és extremadament complex. De camí cap al disseny de sistemes per a la conversió d’energia basats en la llum solar, el CO2 i l’H2O, un pas clau és l’etapa d’oxidació de l’aigua. Aquesta etapa proporciona els electrons necessaris per la producció de combustible. La presència d’un catalitzador és necessària per superar aquesta transformació multielectrònica, ja que requereix una elevada energia. L’objectiu principal d’aquesta tesi és el disseny de compostos artificials que oxidin l’aigua i alliberin oxigen, protons i electrons de manera eficient, com a primer pas cap a l’explotació de la llum. L’estudi d’aquests complexos pot contribuir amb informació valuosa sobre el mecanisme d’oxidació que tenen lloc durant la fotosíntesi. Els resultats obtinguts en aquesta tesi mostren que complexos de ferro i iridi fàcilment a l’abat són capaços de catalitzar l’oxidació de l’aigua de manera eficient. Espècies homogènies en alts estat d’oxidació (IrV/VI, FeV) són les responsables de dur a terme aquest procés redox. La caracterització d’un nou dímer de ferro-ceri unit per un pont oxo constitueix la primera observació directa d’un centre heterodimetàl•lic en un catalitzador artificial d’oxidació de l’aigua. Aquesta espècie constitueix el model estructural i funcional més semblant al centre de MnV-O-CaII present en el PSII.
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Appleby, Kate Mary. "Elucidating mechanisms of palladium and iridium catalysis using parahydrogen." Thesis, University of York, 2016. http://etheses.whiterose.ac.uk/16264/.
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This thesis aims to elucidate mechanisms of palladium and iridium catalysis using para-H2. In palladium catalysis, the debate on the nature of the active catalysts tends to focus on homogeneous palladium monomers or heterogeneous palladium nanoparticles; intermediate palladium clusters are repeatedly overlooked. The research herein aims to ascertain the role of such clusters in palladium catalysis. The conversion of palladium monomers to palladium clusters has been investigated. Reactive palladium monomers have been synthesised. Palladium-catalysed hydrogenation reactions were the focus and the suitability of these monomers for this study was verified by the formation of palladium nanoparticles on addition of hydrogen gas. Nanoparticles were characterised by transmission electron microscopy (TEM). A number of novel monohydride palladium species formed, and were characterised using liquid injection field desorption ionisation mass spectrometry (LIFDI-MS), and nuclear magnetic resonance (NMR) spectroscopy, including para-H2 induced polarisation (PHIP) which is used to enhance NMR signals. Tri-palladium clusters were characterised by LIFDI-MS, advanced NMR spectroscopy, and single-crystal x-ray diffraction (XRD). These were isolated and found to be effective catalysts for hydrogenation reactions and mild Suzuki-Miyaura cross-couplings. PHIP has also been applied in a non-hydrogenative manner using ‘signal amplification by reversible exchange’ (SABRE). This technique has been used to enhance the 1H NMR signals corresponding to pyridazine and phthalazine. The formation of SABRE-active iridium complexes with pyridazine and phthalazine and exchange of hydrogen and the N-heterocycle at iridium has been investigated. SABRE of the 1H NMR resonances was optimised. The potential to use drug derivatives of pyridazine and phthalazine as hyperpolarised contrast agents in magnetic resonance imaging (MRI) was verified by successfully hyperpolarising 5-aminophthalazine (an antifungal) and investigating SABRE in biologically-compatible solvents.
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Magre, Rosich Marc. "Design of tailor-made chiral ligand libraries for C-X bond forming reactions. Study of the key intermediates by NMR and DFT." Doctoral thesis, Universitat Rovira i Virgili, 2016. http://hdl.handle.net/10803/396081.
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El desenvolupament de metodologies per a l’obtenció de compostos enantiomèricament purs ha incrementat en les últimes dècades, ja que aquests productes quirals tenen un gran impacte en la societat actual perquè són la base de fàrmacs, insecticides, perfums i productes naturals, entre altres. La catàlisi asimètrica en la que el catalitzador està basat en un centre metàl·lic i un lligand coordinat al metall ha estat la tècnica més emprada en els últims anys. Aquests complexos organometàl·lics ofereixen propietats molt concretes, com per exemple la seva gran selectivitat en els processos enantioselectius i altes activitats per a reaccions específiques. La modificació del lligand serà clau per a poder obtenir grans nivells de selectivitat i altes activitats; per això els lligands han de ser modulables, la qual cosa permetria poder realitzar canvis estructurals del lligand i poder estudiar la seva influencia en la reacció, i així saber l’estructura idònia del lligand que aporti millors resultats en la catàlisi asimètrica.
En aquest context, aquesta tesi doctoral es basa en la síntesi de diferents lligands quirals fosfit-nitrogen i la seva aplicació en diferents reaccions enantioselectives catalitzades per metall. Més concretament,s'ha treballat en la substitució al·lílica asimètrica catalitzada per pal·ladi, la descarboxilació protonativa d'a-aryl oxindoles catalitzada per pal·ladi, la hidrogenació asimètrica d'olefines poc funcionalitzades catalitzada per iridi, la hidroboració asimètrica d'olefines catalitzada per iridi i la addició enantioselectiva de compostos organoaluminats a aldehids catalitzada per níquel.El desarrollo de metodologías para la obtención de compuestos enantioméricamente puros ha incrementado durante las últimas décadas, debido a la importancia de estos productos quirales en la sociedad actual, ya que son la base de fármacos, insecticidas y perfumes, entre otros. La catálisis asimétrica en la que el catalizador está basado en un centro metálico i un ligando coordinado al metal, ha sido la técnica más usada en los últimos años. Estos complejos organometálicos ofrecen unas propiedades concretas, como por ejemplo su gran selectividad y elevada actividad. La modificación del ligando será clave para la obtención de elevados niveles de selectividad y actividad. Estos ligandos han de ser altamente modulables, lo que permitiría realizar cambios estructurales y así poder estudiar su influencia en la reacción. En este contexto, esta tesis doctoral se basa en la síntesis de ligandos quirales fosfito-nitrogeno y su aplicación en diferentes reacciones enantioselectivas catalizadas por metal. Más concretamente, se ha trabajado en la sustitución alílica asimétrica catalizada por paladio; la descarboxilación protonativa de alfa aril onxindolas catalizada por paladio, la hidrogenación asimétrica de olefinas poco funcionalizadas catalizada por iridio, la hidroboración asimétrica catalizada por iridio y la adición enantioselectiva de compuestos trialquilaluminio a aldehídos, catalizada por níque
Fine chemicals and natural product chemistry rely on enantiomerically pure compounds. The growing demand on these compounds has stimulated the research for efficient asymmetric processes, which provided high activity and selectivity with minimum energy consumption and minimum generation of byproducts. In drugs and also in natural product chemistry, one enantiomer has the desired properties whereas the opposite enantiomer is either inactive or has undesirable side-effects. The discovery of synthetic routes for obtaining enantiomerically pure compounds is therefore one of the most pursued goals in chemistry. Particularly, asymmetric catalysis is one of the most attractive approach because it can provide very high reactivity and selectivity. Usually, with this strategy, a transition-metal complex containing a chiral ligand catalyzes the transformation of a prochiral substrate to one enantiomer as major product. To reach high levels of reactivity and selectivity, several reaction parameters need to be optimized. For example, the design of a chiral ligand is perhaps one of the most crucial step. In this context, this thesis focuses on the development of new chiral ligand libraries, the synthesis of new chiral catalyst and their application in the Pd-catalyzed asymmetric allylic substitution, Pd-catalyzed decarboxylative protonation of oxindoles, Ir-catalyzed asymmetric hydrogenation, Ir-catalyzed asymmetric hydroboration and Ni-1,2-addition of organoaluminum to aldehydes.
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Ez-Zoubir, Mehdi. "Développement de réactions catalytiques pour la formation de liaisons Carbone-Carbone et Carbone-Iode en présence de complexes d'iridium." Paris 6, 2011. http://www.theses.fr/2011PA066021.
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Ce manuscrit présente le développement de nouveaux systèmes catalytiques à base d’iridium pour la création de liaisons C-C et C-I. Ainsi, la dimérisation d’alcynes fonctionnalisés catalysée par un complexe d’iridium (III) {[IrH((rac)-Binap)]2(µ-I)3}+I- a pu être réalisée avec une régio- et stéréosélectivité totales en faveur du produit de couplage (E). De plus, les produits polyinsaturés, issus de la réaction de couplage, ont pu être engagés dans une réaction de cycloisomérisation catalysée au rhodium, permettant un accès à des carbocycles fonctionnalisés. A la suite de ce travail, nous avons mis au point une réaction d’hydroiodation d’alcynes catalysée par le dimère [Ir(cod)Cl]2 en présence de HI et conduisant au vinyle iodé de type Markovnikov. La mise au point de cette réaction, nous a ensuite amené à la découverte d’une nouvelle réaction de iodocyclisation d’ényne qui s’apparente aux réactions de cycloisomérisation en présence d’un nucléophile extérieur. Enfin, la formation de motifs isoindolines et tétrahydroisoquinolines, pharmacophores importants en chimie médicinale, a été effectuée par réaction de cycloaddition [2+2+2] catalysée par le complexe d’iridium (III) {[IrH((rac)-Binap)]2(µ-I)3}+I-
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Franks, Marion A. "The Synthesis and Characterization of Some Ir(III) Dicationic Complexes." Diss., Virginia Tech, 1998. http://hdl.handle.net/10919/30039.
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The complex [IrH(COD)(PMe3)3][Cl]2o2HCl was prepared by the reaction between [Ir(COD)(PMe3)3]Cl and HCl gas in methylene chloride. The product precipitated from the solution and is soluble in polar solvents such as water, acetonitrile, and acetone. [IrH(COD)(PMe3)3][Cl]2o2HCl undergoes reaction in water to form fac-IrCl3(PMe3)3. Also, other [IrH(COD)(PMe3)3][X]2 salts were prepared with X being PF6, OTF, or BF4. It was determined that each salt retained a certain amount of excess acids and [IrH(COD)(PMe3)3][OTF]HOTf was the most stable in the solvent acetonitrile while [IrH(COD)(PMe3)3][PF6]2 showed signs of reaction in acetonitrile after 4 hours. The dicationic salts were also reductively deprotonated by DMSO to form the Ir(I) starting material. Finally a slow equilibrium was noted for [IrH(COD)(PMe3)3][BF4]2 in water by the observation of the reductive deprotonation product.
The grignard reaction was employed to synthesize Ir(CH3)3(PMe3)3. IrCl3(PMe3)3 reacts with methyl grignard in THF/Benzene to form fac-Ir(CH3)3(PMe3)3. Only the facial isomer of this reaction was observed and the product was soluble in nonpolar solvents. Acidolysis was utilized to synthesize fac-IrCH3Cl2(PMe3).3 from the reaction between Ir(CH3)3(PMe3)3 and 2 equivalents of HCl. Ir(III) methyl dications have also been synthesized by the reaction of 2 equivalents triflic acids with fac-Ir(CH3)3(PMe3)3. The product of the reaction, mer-IrCH3(OTf)2(PMe3)3 was used to study the insertion of alkynes into the Iridium methyl bond.
IrHCl2(PMe3)3 was synthesized by the careful acidolysis of IrH2Cl(PMe3)3 using 1 equivalent of HCl. IrH(OTf)2(PMe3)3 was also synthesized by the metathesis of IrHCl2(PMe3)3 with 2.04 equivalents of silver triflate. The product of that reaction, IrH(OTf)2(PMe3)3, has been used to form dimers and trimers of styrene via catalysis and to isomerize alkene alcohols to aldehydes. IrH(OTf)2(PMe3)3 was also used as a polymerization initiator for vinyl and allyl ethers.Ph. D.