Download or read book Design and Synthesis of Rhodium and Iridium Bis 2 Diolefin Catalysts written by Michaela-Christina Melcher and published by . This book was released on 2018 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Rhodium and Iridium Complexes Supported by Chelating Bis N heterocyclic Carbene Ligands written by Roxy Joanne Lowry and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: Eighty-five percent of all industrial chemical processes occur catalytically. The world's expanding appetite for mass production of exotic chemicals necessitates the design and application of enhanced catalysts. To optimize catalytic materials, the detailed relationships between catalyst architecture and reactivity must be determined. Although for many ligand families these relationships are well understood, novel catalysts require in depth empirical investigation to determine these connections. The design of a novel di-N-heterocyclic carbene family of ligands in reported herein. These C2 symmetric ligands are based on the rigid 9,10-dihydro-9,10-ethanoanthracene backbone and designed for utilization in chiral catalysis. Thorough investigation into the relationships between the ligand's structure and the architecture of the resulting rhodium and iridium catalysts directed the design of three generations of our novel ligand family. The first generation, trans-1,1'-[9,10-dihydro-9,10-ethanoanthracene-11,12- diyldimethanediyl]bis(benzylimidazole) bis(triflouromethansulfonate) [DEAM-BI](OTf)2 (2-1), is too flexible to enforce a rigid chiral pocket about a metal center under catalytic conditions. The constrained second generation ligands, trans-1,1'-(9,10-dihydro-9,10-ethanoanthracene.

Download or read book Rhodium Catalysis in Organic Synthesis written by Ken Tanaka and published by John Wiley & Sons. This book was released on 2019-05-06 with total page 684 pages. Available in PDF, EPUB and Kindle. Book excerpt: An essential reference to the highly effective reactions applied to modern organic synthesis Rhodium complexes are one of the most important transition metals for organic synthesis due to their ability to catalyze a variety of useful transformations. Rhodium Catalysis in Organic Synthesis explores the most recent progress and new developments in the field of catalytic cyclization reactions using rhodium(I) complexes and catalytic carbon-hydrogen bond activation reactions using rhodium(II) and rhodium(III) complexes. Edited by a noted expert in the field with contributions from a panel of leading international scientists, Rhodium Catalysis in Organic Synthesis presents the essential information in one comprehensive volume. Designed to be an accessible resource, the book is arranged by different reaction types. All the chapters provide insight into each transformation and include information on the history, selectivity, scope, mechanism, and application. In addition, the chapters offer a summary and outlook of each transformation. This important resource: -Offers a comprehensive review of how rhodium complexes catalyze a variety of highly useful reactions for organic synthesis (e.g. coupling reactions, CH-bond functionalization, hydroformylation, cyclization reactions and others) -Includes information on the most recent developments that contain a range of new, efficient, elegant, reliable and useful reactions -Presents a volume edited by one of the international leading scientists working in the field today -Contains the information that can be applied by researchers in academia and also professionals in pharmaceutical, agrochemical and fine chemical companies Written for academics and synthetic chemists working with organometallics, Rhodium Catalysis in Organic Synthesis contains the most recent information available on the developments and applications in the field of catalytic cyclization reactions using rhodium complexes.

Download or read book Supported Molecular Rhodium Complexes and Dimers written by Dicle Yardimci and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Solid catalysts incorporating transition metals are important in industry, providing cost- effective syntheses, ease of separation from products, and control of selectivity. The metal is often expensive and thus often constitutes only about one percent of the catalyst mass, being highly dispersed on a high-area support. Dispersed metals in industrial catalysts are usually highly nonuniform in structure and challenging to characterize, and consequently relationships between structure and catalyst performance are typically less than fully understood. Our approach to the investigation of supported metal catalysts involves the synthesis of uniform catalytic sites that have essentially molecular character. Supported molecular catalysts can be characterized spectroscopically to provide fundamental understanding of the catalyst structure under reactive atmospheres, and thereby determination of structural changes of working catalysts that can be correlated with the catalytic activity and selectivity. The sample characterization techniques used in this work included infrared (IR), extended X-ray absorption fine structure (EXAFS), and X-ray absorption near edge structure (XANES) spectroscopies, as well as gas chromatography (GC) and mass spectrometry (MS) to characterize reaction products. The catalysts were prepared from the organometallic precursor Rh(C2H4)2(C5H7O2) and the supports MgO and zeolite HY. These catalysts initially incorporated site-isolated, mononuclear rhodium complexes on the supports. The complexes on MgO were treated in H2 at elevated temperatures to form the smallest supported rhodium clusters--rhodium dimers. These catalysts are essentially molecular in character and allowed tailoring of the rhodium nuclearity, the ligands bonded to the rhodium, and the rhodium-support interface. The catalysts incorporated mononuclear Rh(C2H4)2 and Rh(CO)2 complexes; dimeric rhodium clusters with ethyl ligands, and dimeric rhodium clusters with CO ligands. These were tested for the hydrogenation of ethylene. Rhodium in various forms is highly active for catalytic hydrogenation of olefins. However, rhodium has been little investigated for diene hydrogenation, because, like other noble metals in the form of supported clusters or particles, it is unselective. We postulated that new catalytic chemistry of rhodium could emerge if the catalytic species were essentially molecular so that they could be tuned by the choice of the rhodium nuclearity and ligands. Thus, we investigated the influence of the following catalyst design variables on the activity and selectivity of supported rhodium for 1,3-butadiene hydrogenation: (a) the metal nuclearity, ranging from one to several; (b) the electron-donor properties of the support (MgO vs. zeolite Y); and (c) other ligands on the rhodium, including reactive hydrocarbons (ethylene or ethyl) and CO. The data show that extremely small MgO-supported rhodium clusters that are partially carbonylated are highly active and selective for the hydrogenation of 1,3-butadiene to give n-butenes. The support, the rhodium nuclearity, and the ligands on rhodium are crucial to the catalyst selectivity, transforming a metal that is typically regarded as unselective for 1,3-butadiene hydrogenation into one that is highly selective even at high conversions. Transition metals in complexes and clusters tend to aggregate to form of more stable, bulk particles under reactive atmospheres, causing catalyst deactivation. We investigated the initial steps of the aggregation of supported metal species that were highly dispersed on MgO and zeolite HY, synthesizing samples that incorporated supported rhodium complexes bonded to ligands with different reactivities (including the support), and then spectroscopically investigated the formation of extremely small rhodium clusters in the presence of H2. The stability of the rhodium complexes and the stoichiometry of the surface-mediated transformations are regulated by the support and the other ligands bonded to the rhodium, being prompted at a lower temperature with zeolite HY than the better electron-donor MgO when the rhodium complexes incorporate ethylene ligands, but occurring more facilely on the MgO than on the zeolite when the ligands are CO. The preparation of highly uniform rhodium dimers is possible. We infer that results such as those presented here may be useful in guiding the design of stable, highly dispersed supported metal catalysts by choice of the support and other ligands on the metal.

Download or read book Iridium Complexes in Organic Synthesis written by Luis A. Oro and published by John Wiley & Sons. This book was released on 2008-12-03 with total page 424 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ranging from hydrogenation to hydroamination, cycloadditions and nanoparticles, this first handbook to comprehensively cover the topic of iridium in synthesis discusses the important advances in iridium-catalyzed reactions, namely the use of iridium complexes in enantioselective catalysis. A must for organic, complex and catalytic chemists, as well as those working with/on organometallics.

Download or read book Rhodium Catalyzed Hydroformylation written by Piet W.N.M. van Leeuwen and published by Springer Science & Business Media. This book was released on 2006-04-11 with total page 291 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the last decade there have been numerous advances in the area of rhodium-catalyzed hydroformylation, such as highly selective catalysts of industrial importance, new insights into mechanisms of the reaction, very selective asymmetric catalysts, in situ characterization and application to organic synthesis. The views on hydroformylation which still prevail in the current textbooks have become obsolete in several respects. Therefore, it was felt timely to collect these advances in a book. The book contains a series of chapters discussing several rhodium systems arranged according to ligand type, including asymmetric ligands, a chapter on applications in organic chemistry, a chapter on modern processes and separations, and a chapter on catalyst preparation and laboratory techniques. This book concentrates on highlights, rather than a concise review mentioning all articles in just one line. The book aims at an audience of advanced students, experts in the field, and scientists from related fields. The didactic approach also makes it useful as a guide for an advanced course.

Download or read book Synthesis Characterization and Catalytic Performance of Rhodium and Iridium Complexes Supported in Dealuminated HY Zeolite written by Claudia Martinez Macias and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Essentially molecular supported catalysts were synthesized by using organometallic complexes as precursors, such as Rh(CO)2(acac), Rh(C2H4)2(acac), Ir(CO)2(acac), and Ir(C2H4)2(acac) (where acac is acetylacetonate) and HY zeolite as a support. A goal was to obtain highly uniform solid catalysts with well-defined structures. Characterization by X-ray absorption (XAS) and infrared (IR) spectroscopies confirmed the anchoring of the metal to the support with a high degree of uniformity. IR and 29Si and 27Al nuclear magnetic resonance (NMR) spectra characterize the presence of amorphous regions in the zeolite, and scanning transmission electron microscopy (STEM) identifies these amorphous regions, where iridium is more susceptible to aggregation than in the crystalline regions. Treatment of Ir(CO)2/HY zeolite with C2H4 and H2 at room temperature led to a family of species which includes Ir(CO)2, Ir(CO)(C2H4), Ir(CO)(C2H4)2, Ir(CO)(C2H5) and, tentatively, Ir(CO)(H). The identification of the species is based on XAS and IR spectra (including spectra of samples made with isotopically labeled ligands, 13CO and D2O) and density functional theory (DFT) calculations. The catalytic performance of isostructural rhodium and iridium species incorporating CO as a ligand was measured for the ethylene conversion; the CO not only acts as an inhibitor but it also as a probe molecule providing information about the electronic properties of the metal and of the species present during reaction. When isostructural rhodium and iridium diethylene species are bonded near each other on HY zeolite, the iridium complexes alter the selectivity of rhodium by spilling over hydrogen that hinders the interaction between ethylene and the acidic sites of the zeolite that act in concert with the rhodium, causing it to favor ethylene hydrogenation over dimerization. All these results show how structurally simple solid catalysts can be used to facilitate fundamental understanding of catalysts and their performance.

Download or read book Modern Rhodium Catalyzed Organic Reactions written by P. Andrew Evans and published by John Wiley & Sons. This book was released on 2006-03-06 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rhodium has proven to be an extremely useful metal due to its ability to catalyze an array of synthetic transformations, with quite often-unique selectivity. Hydrogenation, C-H activation, allylic substitution, and numerous other reactions are catalyzed by this metal, which presumably accounts for the dramatic increase in the number of articles that have recently emerged on the topic. P. Andrew Evans, the editor of this much-needed book, has assembled an internationally renowned team to present the first comprehensive coverage of this important area. The book features contributions from leaders in the field of rhodium-catalyzed reactions, and thereby provides a detailed account of the most current developments, including: Rhodium-Catalyzed Asymmetric Hydrogenation (Zhang) Rhodium-Catalyzed Hydroborations and Related Reactions (Brown) Rhodium-Catalyzed Asymmetric Addition of Organometallic Reagents to Electron Deficient Olefins (Hayashi) Recent Advances in Rhodium(I)-Catalyzed Asymmetric Olefin Isomerization and Hydroacylation Reactions (Fu) Stereoselective Rhodium(I)-Catalyzed Hydroformylation and Silylformylation Reactions and Their Application to Organic Synthesis (Leighton) Carbon-Carbon Bond-Forming Reactions Starting from Rh-H or Rh-Si Species (Matsuda) Rhodium(I)-Catalyzed Cycloisomerization and Cyclotrimerization Reactions (Ojima) The Rhodium(I)-Catalyzed Alder-ene Reaction (Brummond) Rhodium-Catalyzed Nucleophilic Ring Cleaving Reactions of Allylic Ethers and Amines (Fagnou) Rhodium(I)-Catalyzed Allylic Substitution Reactions and their Applications to Target Directed Synthesis (Evans) Rhodium(I)-Catalyzed [2+2+1] and [4+1] Carbocyclization Reactions (Jeong) Rhodium(I)-Catalyzed [4+2] and [4+2+2] Carbocyclizations (Robinson) Rhodium(I)-Catalyzed [5+2], [6+2], and [5+2+1] Cycloadditions: New Reactions for Organic Synthesis (Wender) Rhodium(II)-Stabilized Carbenoids Containing both Donor and Acceptor Substituents (Davies) Chiral Dirhodium(II)Carboxamidates for Asymmetric Cyclopropanation and Carbon-Hydrogen Insertion Reactions (Doyle) Cyclopentane Construction by Rhodium(II)-Mediated Intramolecular C-H Insertion (Taber) Rhodium(II)-Catalyzed Oxidative Amination (DuBois) Rearrangement Processes of Oxonium and Ammonium Ylides Formed by Rhodium(II)-Catalyzed Carbene-Transfer (West) Rhodium(II)-Catalyzed 1,3-Dipolar Cycloaddition Reactions (Austin) "Modern Rhodium-Catalyzed Organic Reactions" is an essential reference text for researchers at all levels in the general area of organic chemistry. This book provides an invaluable overview of the most significant developments in this important area of research, and will no doubt be an essential text for researchers at academic institutions and professionals at pharmaceutical/agrochemical companies.

Download or read book Synthesis Structural Characterization and Reactivity of 2 2 bis diphenylphosphinobenzideneamino 6 6 dimethylbiphenyl Complexes of Rhodium I and Iridium I written by Tricia Leslie Marxen and published by . This book was released on 1982 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis and Characterization of Rhodium and Iridium Complexes with the Bis dimethylsilylcyclopentadienyl Ligand written by Gordon J. Hunter and published by . This book was released on 2005 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis of Electrophilic Rhodium and Iridium Complexes and Investigation of Reactivity for C H Bond Activation and Functionalization written by Kate E. Allen and published by . This book was released on 2013 with total page 173 pages. Available in PDF, EPUB and Kindle. Book excerpt: Direct methods for the transformation of alkanes into alcohols, alkenes, amines and other functionalized products would have a great impact on industrial processes. In this thesis the work described is aimed at developing electrophilic Rh and Ir systems to promote C-H bond activation and functionalization of alkanes and arenes. Several approaches have been taken to prepare the target complex [Tp*Ir(OH2)3]+ (Tp* = hydridotris(3,5-dimethylpyrazoyl)borate). While this species has not been synthesized, C-N coupling between ethylene and N-iodosuccinimide has been observed during the course of this study and is promoted by Tp*Ir(C2H4)2. Electrophilic Rh and Ir complexes bearing dimethylbutadiene (DMB) ligands have been found to be poor species for C-H activation due to low stability at elevated temperatures. Interestingly, formation of the unique five-coordinate [(DMB)Ir(COE)Cl]2 dimer has been observed. Alkane dehydrogenation using ([superscript dm]Phebox)Ir(OAc)2(OH2) ([superscript dm]Phebox = 2,6-bis(4,4-dimethyloxazolinyl)-3,5-dimethylphenyl) is promoted at 200 °C and results in quantitative formation of olefin and (([superscript dm]Phebox)Ir(OAc)H. At early reaction times 1-octene is the major product, supporting terminal C-H activation by the Ir center. Oxygen can be utilized in this system as a hydrogen acceptor to promote regeneration of the Ir bisacetate species at room temperature. This is the first example of regeneration of a complex for dehydrogenation using oxygen. Unfortunately, the system is not catalytic as the reaction with oxygen is not compatible with the high temperatures required for C-H bond activation. In order to expand the number of examples of alkane dehydrogenation at Ir[superscript III] centers, a second system utilizing the [superscript tBu]NOCON ([superscript tBu]NOCON = 4,6-di-tert-butyl-(1,3-bis(2-pyridyloxy)benzene)) pincer ligand has been developed. Complexes ([superscript tBu] NOCON)M(OAc)2OH2 (M = Rh or Ir) were synthesized and explored for C-H bond functionalization. The Ir analogue promotes alkane dehydrogenation at 200 °C, but is not stable under the reaction conditions. Arene functionalization has also been explored using Ir-aryl complexes. The product of benzene C-H activation, (Phebox)Ir(OAc)Ph has been investigated for arene functionalization using hypervalent iodide reagents and CO. Reactions utilizing C6F5I(TFA)2 are promising and may potentially yield functionalized arene. Coordination of CO to the Ir center has been observed and isomerization of the trans product, ([superscript dm]Phebox)Ir(CO)(OAc)Ph, occurs at room temperature to yield the cis isomer ([superscript dm] Phebox)Ir(OAc)(CO)Ph.

Download or read book Advanced Strategies for Catalyst Design written by Laura Orian and published by MDPI. This book was released on 2021-04-21 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: The invention of novel and improved catalysts has a valuable impact on human activities and on our planet. Efficient catalysts are expected to be stable, active, and selective. In the past, the development of new catalysts has mainly depended on trial and error, a laborious and time-consuming approach. Nowadays, the mechanistic details of numerous important chemical reactions have been unraveled, and this information is useful for intelligently design novel catalysts. Thus, all the efforts devoted to facilitating a deep understanding of intricate catalytic mechanisms and to the preparation of novel catalysts relying on this are priceless. Chemists must set up adequate strategies, merging experimental and computational knowledge and abilities toward tuning the performance of molecules that might be successful in the lab. The contributions in this book collection are some examples of this modern chemical design.

Download or read book Development of Novel Rhodium and Iridium Complexes with a Fac chelating Ligand for Electrophilic C H Activation written by Jennifer Lee Rhinehart and published by . This book was released on 2011 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Several new bis-3,5(dimethylpyrazol-1-yl)acetate rhodium and iridium complexes were synthesized from MCl3?H2O. [Rh(bdmpza)Cl3]- was isolated with three different cations, lithium, sodium and tetraethylamonium, to obtain a full characterization profile. Analogously, [Ir(bdmpza)Cl3]- was isolated with two different cations, lithium and sodium, and characterized by 1H NMR, 13C NMR, elemental analysis and X-ray crystal structure determination. A neutral rhodium complex, [Rh(bdmpza)Cl2(py)], was also isolated as two isomers by addition of pyridine. Reaction of [Rh(bdmpza)Cl3]- and [Rh(bdmpza)Cl2(py)] with dimethylzinc afforded three new complexes, [Rh(bdmpza)Cl2(Me)]-, [Rh(bdmpza)Cl(Me)2]- and [Rh(bdmpza)Cl(Me)(py)]. Stoichiometric and catalytic C-H activation of benzene was investigated for these new rhodium methyl complexes. Novel rhodium and iridium precatalysts catalysts, [Rh(bdmpza)Cl3]- Na+, [Ir(bdmpza)Cl3]- Na+ and [Rh(bdmpza)Cl2(py)], were subjected to H/D exchange conditions with benzene and deuterated trifluoroacetic acid, acetic acid and methanol in the presence of a halide abstractor. Optimum conditions of silver triflate, deuterated trifuoroacetic acid, 100°C and 24 hours were identified to conduct arene H/D exchange studies. Most arenes investigated showed modest H/D exchange in the ring, while branched [beta]-sp3C-H bonds also showed affinity for H/D exchange. Mechanistic studies of [beta]-sp3C-H H/D exchange were carried out, including synthesis of [Rh(bdmpz)Cl3(py)], which does not contain the pendant acetate group"--Leaf vi.

Download or read book Synthesis and Characterization of Supported Organometallic Rhodium I Catalysts written by Donald Nilan Marquardt and published by . This book was released on 1974 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Exo closo Carborane Complexes of Rhodium and Iridium written by Adem Rifat and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Rhodium and Iridium Coordinated Aminyl Radicals written by Nicola Donati and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis and Electrochemistry of Iridium Rhodium and Silver Pyridinyl Bis oxazoline Complexes written by Olga Rebecca Tarkington and published by . This book was released on 2006 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goals of this research project were to synthesize iridium and rhodium pybox complexes and study their electrochemistry. The synthesis of RhCI[subscript]3(pybox) 2 was previously reported and reproduced in this study. It was determined that bulk reduction of 2 at the wave at E[subscript]pc = -1.68 V (all potentials referenced to Fc/Fc[superscript]+) by 2 electrons generates a product, that upon back oxidation results in reformation of the starting material 2. NMR and electrochemical studies support the formation of RhCI(pybox) 19 upon bulk reduction of 2 in THF solution and the formation of RhCI[subscrit]2(CH[subscript]2CI)(pybox) 18 upon bulk reduction in methylene chloride solution. The synthesis of several pybox complexes of iridium (3, 10, 12, and 17) was attempted. Taken together, [superscript]1H NMR, ESI-MS, and C, H analysis data support the formation of the new compound 10, which was produced in low overall yield. Cyclic voltammetry studies of 10 in THF solution revealed two chemically irreversible reduction waves at E[subscript]pc = -1.76 V and -2.35 V plus a number of chemically irreversible oxidation waves at E[subscript]pa = -2.10 V, -0.24 V and 0.42 V. Isolation of compound 3, 12, or 17 was attempted but not achieved.