Download or read book Bifunctional Rhodium and Iridium Platforms Towards C H Activation written by Travis John Morrow and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Pendent nucleophiles are essential partners in the cleavage and formation of bonds with hydrogen (e.g. protonation/deprotonation), but binding of the pendent group to the metal and the potential trapping of complexes in inactive states are a significant problem. The dipyridylmethane-based ligand framework bis(2-pyridyl)-N-pyrrolidinomethane([superscript]R,pyrCPy2), bearing a hemilabile pyrrolidine moiety, has been synthesized and complexes of the type [([superscript]R,pyrCPy2)M(COD)]X (COD = 1,5-cyclooctadiene) were prepared. The solution-phase ligand dynamics and relative protonation preferences were investigated via1H NMR spectroscopy; although favorable, pendent amine binding does not kinetically inhibit pendent base protonation. Protonation at the metal (with concomitant pyrrolidine binding) has been found to be favorable for Ir, whereas N-protonation is favorable for Rh. DFT calculations predict that the RhIII hydrides have much higher relative acidities than their Ir congeners (∆pK[subscript]a ≃ 7–8 in CH2Cl2), and are also more acidic than the strong acid[H(OEt2)2][B(C6F5)4]. The second part of this dissertation examines oxidative addition of carbon-halogen bonds at transition metals, which typically follow either a two-electron pathway (concerted MR/M-X formation) or a radical chain pathway (stepwise M-R/M-X formation). When the reactive metal species is generated slowly, however, both mechanisms can compete to yield unexpected reactivity paths. The present report highlights the synthesis of rhodiummethylidenes from chloroalkanes (e.g. CH2Cl2 and CHCl3) at POP-pincer frameworks(e.g. POP = 4,6-bis(di-tert-butylphosphino)dibenzo[b,d]furan) via a cascade of halide abstraction and electron transfer steps. Experimental and computational studies are covered that support our proposed mechanism, including characterization of important reaction intermediates. The overall transformation presented represents a route towards reactive metal alkylidenes using milder and less-reactive carbenoid precursors than what is presently used.

Download or read book Iridium and Rhodium Analogues of the Shilov Cycle Catalyst and the Investigation and Applications of the Reduction Coupled Oxo Activation ROA Mechanistic Motif Towards Alkane Upgrading written by Ross Fu and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation will cover several disparate topics, with the overarching theme centering on the investigation of organometallic C-H activation and hydrocarbon transformation and upgrading. Chapters 2 and 3 discuss iridium and rhodium analogues of the Shilov cycle catalyst for methane to methanol oxidation, and Chapter 4 on the recently discovered ROA mechanistic motif in catalysts for various alkane partial oxidation reactions. In addition, Chapter 5 discusses the mechanism of nickel pyridine bisoxazoline Negishi catalysts for asymmetric and stereoconvergent C-C coupling, and the appendices discuss smaller projects on rhodium H/D exchange catalysts and DFT method benchmarking.

Download or read book Rhodium Catalyzed C C Bond Formation Via Heteroatom Directed C H Bond Activation written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Once considered the 'holy grail' of organometallic chemistry, synthetically useful reactions employing C-H bond activation have increasingly been developed and applied to natural product and drug synthesis over the past decade. The ubiquity and relative low cost of hydrocarbons makes C-H bond functionalization an attractive alternative to classical C-C bond forming reactions such as cross-coupling, which require organohalides and organometallic reagents. In addition to providing an atom economical alternative to standard cross - coupling strategies, C-H bond functionalization also reduces the production of toxic by-products, thereby contributing to the growing field of reactions with decreased environmental impact. In the area of C-C bond forming reactions that proceed via a C-H activation mechanism, rhodium catalysts stand out for their functional group tolerance and wide range of synthetic utility. Over the course of the last decade, many Rh-catalyzed methods for heteroatom-directed C-H bond functionalization have been reported and will be the focus of this review. Material appearing in the literature prior to 2001 has been reviewed previously and will only be introduced as background when necessary. The synthesis of complex molecules from relatively simple precursors has long been a goal for many organic chemists. The ability to selectively functionalize a molecule with minimal pre-activation can streamline syntheses and expand the opportunities to explore the utility of complex molecules in areas ranging from the pharmaceutical industry to materials science. Indeed, the issue of selectivity is paramount in the development of all C-H bond functionalization methods. Several groups have developed elegant approaches towards achieving selectivity in molecules that possess many sterically and electronically similar C-H bonds. Many of these approaches are discussed in detail in the accompanying articles in this special issue of Chemical Reviews. One approach that has seen widespread success involves the use of a proximal heteroatom that serves as a directing group for the selective functionalization of a specific C-H bond. In a survey of examples of heteroatom-directed Rh catalysis, two mechanistically distinct reaction pathways are revealed. In one case, the heteroatom acts as a chelator to bind the Rh catalyst, facilitating reactivity at a proximal site. In this case, the formation of a five-membered metallacycle provides a favorable driving force in inducing reactivity at the desired location. In the other case, the heteroatom initially coordinates the Rh catalyst and then acts to stabilize the formation of a metal-carbon bond at a proximal site. A true test of the utility of a synthetic method is in its application to the synthesis of natural products or complex molecules. Several groups have demonstrated the applicability of C-H bond functionalization reactions towards complex molecule synthesis. Target-oriented synthesis provides a platform to test the effectiveness of a method in unique chemical and steric environments. In this respect, Rh-catalyzed methods for C-H bond functionalization stand out, with several syntheses being described in the literature that utilize C-H bond functionalization in a key step. These syntheses are highlighted following the discussion of the method they employ.

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 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 Centre de recherche de l Univ de Paris VIII Vincennes Groupe Cultures id ologies et soci t s des XIXe et XXe si cles written by and published by . This book was released on 1976 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Rhodium Catalysis written by Carmen Claver and published by Springer. This book was released on 2017-12-15 with total page 291 pages. Available in PDF, EPUB and Kindle. Book excerpt: The series Topics in Organometallic Chemistry presents critical overviews of research results in organometallic chemistry. As our understanding of organometallic structure, properties and mechanisms increases, new ways are opened for the design of organometallic compounds and reactions tailored to the needs of such diverse areas as organic synthesis, medical research, biology and materials science. Thus the scope of coverage includes a broad range of topics of pure and applied organometallic chemistry, where new breakthroughs are being achieved that are of significance to a larger scientific audience. The individual volumes of Topics in Organometallic Chemistry are thematic. Review articles are generally invited by the volume editors. All chapters from Topics in Organometallic Chemistry are published OnlineFirst with an individual DOI. In references, Topics in Organometallic Chemistry is abbrev iated as Top Organomet Chem and cited as a journal.

Download or read book C H Activation Via Iridium and Rhodium Electrocatalysis and Undirected Electrochemical Fluorination written by Maximilian Daniel Stangier and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In past decades, transition metal-catalyzed C-H activation has emerged as an increasingly viable toolbox for the step- and atom economic formation of C-C and C-Het bonds. However, oxidative C-H transformations heavily rely on stoichiometric amounts of toxic and expensive metal oxidants. To overcome the drawback of sacrificial oxidants, organic electrochemistry has proven to be a powerful and sustainable alternative for transition metal-catalyzed C-H activations. Within this thesis, the concept of metallaelectrocatalysis was extended towards iridium electro-catalyzed C-H activation and the e...

Download or read book Modern Arylation Methods written by Lutz Ackermann and published by John Wiley & Sons. This book was released on 2009-04-22 with total page 561 pages. Available in PDF, EPUB and Kindle. Book excerpt: Today, arylation methods are belonging to the most important reaction types in organic synthesis. Lutz Ackermann, a young and ambitious professor has gathered a number of top international authors to present the first comprehensive book on the topic. Starting from a historical review, the book covers hot topics like Palladium-catalyzed arylation of N-H and alpha-C-H-acidic Bonds, Copper-catalyzed arylation of N-H and O-H Bonds, direct arylation reactions, carbanion aromatic synthesis, arylation reactions of alkenes, alkynes and much more. This compact source of high quality information is indispensable to synthetic chemists and those working in the pharmaceutical and chemical industry.

Download or read book Activation of Small Molecules written by William B. Tolman and published by John Wiley & Sons. This book was released on 2006-12-13 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first to combine both the bioinorganic and the organometallic view, this handbook provides all the necessary knowledge in one convenient volume. Alongside a look at CO2 and N2 reduction, the authors discuss O2, NO and N2O binding and reduction, activation of H2 and the oxidation catalysis of O2. Edited by the highly renowned William Tolman, who has won several awards for his research in the field.

Download or read book Iridium Catalysis written by Pher G. Andersson and published by Springer Science & Business Media. This book was released on 2011-01-05 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt: From the contents: Robert H Crabtree: Introduction and History. - Montserrat Diéguez, Oscar Pàmies and Carmen Claver: Iridium-catalysed hydrogenation using phosphorous ligands. - David H. Woodmansee and Andreas Pfaltz: Iridium Catalyzed Asymmetric Hydrogenation of Olefins with Chiral N,P and C,N Ligands. - Ourida Saidi and Jonathan M J Williams: Iridium-catalyzed Hydrogen Transfer Reactions. - John F. Bower and Michael J. Krische: Formation of C-C Bonds via Iridium Catalyzed Hydrogenation and Transfer Hydrogenation. - Jongwook Choi, Alan S. Goldman: Ir-Catalyzed Functionalization of CH Bonds. - Mark P. Pouy and John F. Hartwig: Iridium-Catalyzed Allylic Substitution. - Daniel Carmona and Luis A. Oro: Iridium-catalyzed 1.3-dipolar cycloadditions.

Download or read book Advances in Organometallic Chemistry written by Pedro J. Perez and published by Academic Press. This book was released on 2020-03-17 with total page 314 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in Organometallic Chemistry, Volume 73, the latest release in this longstanding serial, is known for its comprehensive coverage of topics in organometallic synthesis, reactions, mechanisms, homogeneous catalysis, and more. It is ideal for a wide range of researchers involved in organometallic chemistry, including synthetic protocols, mechanistic studies and practical applications. Specific chapters in this new release include Metal carbonyl promoted multicomponent coupling of alkyne for synthesis of heterocyclic compounds, Group 10 metal(0) complexes stabilized by phosphorus and carbon donor ligands, Synthesis of Nitrogen-containing Molecules via Transition Metal-Catalyzed Reactions on Isoxazoles, Anthraniils and Benzoisoxazoles, and more. Contains contributions from leading authorities in the field of organometallic chemistry Covers topics in organometallic synthesis, reactions, mechanisms, homogeneous catalysis, and more Informs and updates readers on the latest developments in the field Carefully edited to provide easy-to-read material

Download or read book Pincer Compounds written by David Morales-Morales and published by Elsevier. This book was released on 2018-04-11 with total page 756 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pincer Compounds: Chemistry and Applications offers valuable state-of-the-art coverage highlighting highly active areas of research—from mechanistic work to synthesis and characterization. The book focuses on small molecule activation chemistry (particularly H2 and hydrogenation), earth abundant metals (such as Fe), actinides, carbene-pincers, chiral catalysis, and alternative solvent usage. The book covers the current state of the field, featuring chapters from renowned contributors, covering four continents and ranging from still-active pioneers to new names emerging as creative strong contributors to this fascinating and promising area. Over a decade since the publication of Morales-Morales and Jensen’s The Chemistry of Pincer Compounds (Elsevier 2007), research in this unique area has flourished, finding a plethora of applications in almost every single branch of chemistry—from their traditional application as very robust and active catalysts all the way to potential biological and pharmaceutical applications. Describes the chemistry and applications of this important class of organometallic and coordination compounds Includes contributions from global leaders in the field, featuring pioneers in the area as well as emerging experts conducting exciting research on pincer complexes Highlights areas of promising and active research, including small molecule activation, earth abundant metals, and actinide chemistry

Download or read book C H Activation for Asymmetric Synthesis written by Françoise Colobert and published by John Wiley & Sons. This book was released on 2019-11-11 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides, in one handbook, comprehensive coverage of one of the hottest topics in stereoselective chemistry Written by leading international authors in the field, this book introduces readers to C-H activation in asymmetric synthesis along with all of its facets. It presents stereoselective C-H functionalization with a broad coverage, from outer-sphere to inner-sphere C-H bond activation, and from the control of olefin geometry to the induction of point, planar and axial chirality. Moreover, methods wherein asymmetry is introduced either during the C-H activation or in a different elementary step are discussed. Presented in two parts?asymmetric activation of C(sp3)-H bonds and stereoselective synthesis implying activation of C(sp2)-H bonds?CH-Activation for Asymmetric Synthesis showcases the diversity of stereogenic elements, which can now be constructed by C-H activation methods. Chapters in Part 1 cover: C(sp3)-H bond insertion by metal carbenoids and nitrenoids; stereoselective C-C bond and C-N bond forming reactions through C(sp3)?H bond insertion of metal nitrenoids; enantioselective intra- and intermolecular couplings; and more. Part 2 looks at: C-H activation involved in stereodiscriminant step; planar chirality; diastereoselective formation of alkenes through C(sp2)?H bond activation; amongst other methods. -Covers one of the most rapidly developing fields in organic synthesis and catalysis -Clearly structured in two parts (activation of sp3- and activation of sp2-H bonds) -Edited by two leading experts in C-H activation in asymmetric synthesis CH-Activation for Asymmetric Synthesis will be of high interest to chemists in academia, as well as those in the pharmaceutical and agrochemical industry.

Download or read book Olefin Polymerization written by Walter Kaminsky and published by Wiley-VCH. This book was released on 2006-08-18 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: With an enormous velocity, olefin polymerization has expanded to one of the most significant fields in polymers since the first industrial use about 50 years ago. In 2005, 100 million tons of polyolefins were produced - the biggest part was catalyzed by metallorganic compounds. The Hamburg Macromolecular Symposium 2005 with the title "Olefin Polymerization" involved topics such as new catalysts and cocatalysts, kinetics, mechanism and polymer reaction engineering, synthesis of special polymers, and characterization of polyolefins. The conference combined scientists from different disciplines to discuss latest research results of polymers and to offer each other the possibility of cooperation. This is reflected in this volume, which contains invited lectures and selected posters presented at the symposium.

Download or read book Arene Chemistry written by Jacques Mortier and published by John Wiley & Sons. This book was released on 2015-11-30 with total page 992 pages. Available in PDF, EPUB and Kindle. Book excerpt: Organized to enable students and synthetic chemists to understand and expand on aromatic reactions covered in foundation courses, the book offers a thorough and accessible mechanistic explanation of aromatic reactions involving arene compounds. • Surveys methods used for preparing arene compounds and their transformations • Connects reactivity and methodology with mechanism • Helps readers apply aromatic reactions in a practical context by designing syntheses • Provides essential information about techniques used to determine reaction mechanisms

Download or read book Hydrogen Storage written by Thomas Zell and published by Walter de Gruyter GmbH & Co KG. This book was released on 2019-01-14 with total page 391 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydrogen is believed to be the energy source of the future, enabling zero-emission and efficient production of power. This comprehensive publication presents a broad spectrum of various chemical aspects of hydrogen storage. The authors also address global climate change issues, carbon dioxide sequestration problems and CO2-based hydrogen storage.