Download or read book The Synthesis Characterization and Study of Tetranuclear Linear Metal Chain Complexes Based on Tetrakis diisocyanide Rhodium Dimers written by Marlene Marie Bringedahl Mixa and published by . This book was released on 1985 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dissertation Abstracts International written by and published by . This book was released on 1986 with total page 740 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book American Doctoral Dissertations written by and published by . This book was released on 1985 with total page 696 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Doctoral Degree Recipients written by University of Minnesota and published by . This book was released on 1985 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book American Chemical Society Directory of Graduate Research 1987 written by American Chemical Society, Committee on Professional Training Staff and published by . This book was released on 1987 with total page 1390 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Synthesis Structural Characterization and Spectroelectrochemical Studies of a Tetranuclear Square planar Rhodium Complex written by Brian Mark Breczinski and published by . This book was released on 1996 with total page 306 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Structure and Reactivity of Transition Metal Complexes Containing P O and N donor Ligands written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis and Characterization of New Rhodium carbene and New Iron carbene Complexes written by Matthew Ryan and published by . This book was released on 2013 with total page 402 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis and Application of Rhodium I Fischer Carbene Complexes written by Granny Kabelo Ramollo and published by . This book was released on 2016 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study, novel rhodium(I) carbene complexes were synthesized and fully characterized via a carbene ligand transfer methodology from Group 6 Fischer carbene complex precursors and subsequent ligand modification. The classic Fischer route was followed towards the isolation of mono- and biscarbene complexes of the form [M(CO)5{C(OR)R'}] [M = Cr, W; R = Me, Et; R' = 2-furyl, 2-thienyl, ferrocenyl] (complexes 1 6, 9 and 10), and [M(CO)5?{C(OR)-R''-C(OR)}M(CO)5] [M = Cr; R = Me, Et; R'' = 2,2'-bithien-5,5'-diyl, 2,5-furadiyl, 1,1'-ferrocendiyl] (complexes 7, 8 and 11), respectively. Analogous aminocarbene complexes [M(CO)5{C(NH2)R'}] [M = Cr, W; R' = 2-thienyl, ferrocenyl) (complexes 12 and 13) were prepared by simple aminolyses of the alkoxycarbene complex precursors and all isolated products were characterized using NMR and FT-IR spectroscopic methods, the results of which were comparable with literature values. Transmetallation techniques were employed in an attempt to transfer the carbene ligands to a rhodium(I) metal center of the dimeric [Rh(cod)Cl]2 precursor to result in novel 2-furyl, 2-thienyl and ferrocenyl Fischer carbene complexes of rhodium(I). Only the ferrocenylcarbene complex 15 [Rh(cod)Cl{C(OEt)Fc) were found to be stable enough to isolate, as the heteroaryl (thienyl, furyl) substituted carbene ligands dissociated in solution, with resultant decomposition dimerization to form the corresponding alkene and starting [Rh(cod)Cl]2 complex, as indicated by NMR spectroscopy. The ferrocenylcarbene complex 15 was then employed as a precursor for the syntheses of all other rhodium(I) carbene complexes via cod ligand substitution and aminolysis reactions to isolate mono- and dicarbonylcarbene complexes 16 23, [Rh(LL)Cl{C(X)Fc}] [LL = cod, (CO)2, (CO, PPh3), (CO, PCy3), (CO, P(OPh3)), (CO, AsPh3); X = OEt,NHnPr], with variable ?-acceptor properties. Full characterization of the novel complexes were achieved by single crystal XRD and spectroscopic methods. From the FT-IR data collected, the donor ability of the electronic environment around the rhodium(I) center was found to correlate with the known electron-donor ability of the coligands in the order PCy3>PPh3,AsPh3>P(OPh)3. This trend was corroborated by cyclic voltammetric methods through which the electron-withdrawing effects of the coligands were studied, and it was confirmed that the cod ligand is the most electrondonating whilst the dicarbonyls were found to be the least donating in the series. In addition, the increased electron donation of the aminocarbene ligands compared to the ethoxycarbene ligands was found to significantly influence the redox potentials of the metal centre in the studied complexes. The isolated rhodium(I) Fischer carbene complexes 15 - 22 were screened as catalyst precursors for the hydroformylation of 1-octene. Good to excellent catalytic activities, with selectivity toward the formation of the linear nonanal, was observed. These results were found to be comparable to results reported for rhodium(I) N-heterocyclic carbene complexes. A mercury-drop test was done to exclude a heterogeneous catalytic mode of action. Finally, the stability of the catalyst precursor 15 (and 17) was probed by an NMR experiment carried out under hydroformylation conditions. The Rh-Ccarbene bond is retained, although the presumed catalytically active species, the rhodium carbene carbonyl hydride complex could not be identified.
Download or read book Synthesis Characterization and Electrochemical Studies on Some Selected Dinuclear Rhodium Complexes written by Christopher James Janke and published by . This book was released on 1986 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Polynuclear Transition Metal Complexes Based on Azolyl Linkers Synthesis Characterization and Proterties written by Zhaoyang Wang and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Functionalised N Heterocyclic Carbene Complexes written by Olaf Kühl and published by John Wiley & Sons. This book was released on 2010-02-02 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt: N-heterocyclic carbenes (NHCs) have found increasing use as reagents for a range of organic transformations and in asymmetric organocatalysis. The performance of these molecules can be improved and tuned by functionalisation. Functionalised carbenes can anchor free carbenes to the metal site, introduce hemilability, provide a means to immobilise transition metal carbene catalysts, introduce chirality, provide a chelate ligand or bridge two metal centres. NHC can be attached to carbohydrates and campher, derived from amino acids and purines, they can be used as organocatalysts mimicking vitamin B1 or as weak “solvent” donors in lanthanide chemistry. Functionalised N-Heterocyclic Carbene Complexes describes major trends in functionalised NHC ligands, aiming to assist readers in their attempts to develop and apply their own functionalised carbenes. After an introduction to the chemistry and behaviour of NHC, the book gives a detailed description of functionalised carbenes and their complexes according to a range of functional groups, each with a discussion of the synthetic route, structure, stability and performance. Functionalised N-Heterocyclic Carbene Complexes is an essential guide to fine-tuning this important class of compounds for practitioners, researchers and advanced students working in synthetic organometallic and organic chemistry and catalysis.
Download or read book Inorganic Syntheses Volume 23 written by and published by John Wiley & Sons. This book was released on 2009-09-22 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt: The volumes in this continuing series provide a compilation of current techniques and ideas in inorganic synthetic chemistry. Includes inorganic polymer syntheses and preparation of important inorganic solids, syntheses used in the development of pharmacologically active inorganic compounds, small-molecule coordination complexes, and related compounds. Also contains valuable information on transition organometallic compounds including species with metal-metal cluster molecules. All syntheses presented here have been tested.
Download or read book Macrocyclic Chemistry written by K. Gloe and published by Springer Science & Business Media. This book was released on 2005-12-05 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt: Macrocyclic Chemistry: Current Trends and Future Perspectives illustrates essential concepts in this expanding research field covering both basic and applied studies. Written by well-known experts from around the world, the topics of the chapters range from new macrocyclic architectures with different functions and self-assembly processes through to the modeling and dynamics of such systems. The content also reflects on application possibilities in analytical chemistry, separation processes, material preparation and medicine. Thus this book serves as a creative source of research strategies and methodic tools. Providing an excellent overview of the field, this book will be a valuable resource for researchers in industry and academic institutions as well as for teachers of science and graduate students. This book is devoted to the long-standing tradition of the International Symposia on Macrocyclic Chemistry (ISMC) and published to coincide with the 30th meeting, Dresden, Germany.
Download or read book Copper I Chemistry of Phosphines Functionalized Phosphines and Phosphorus Heterocycles written by Maravanji S. Balakrishna and published by Elsevier. This book was released on 2019-04-26 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Copper(I) Complexes of Phosphines, Functionalized Phosphines and Phosphorus Heterocycles is a comprehensive guide to one of the most widely used and extensively studied metals: copper. The numerous practical applications of copper compounds are discussed, including homogeneous and heterogeneous catalysis and their use as fungicides, pesticides, pigments for paints, resins and glasses, and in high-temperature superconductors. The remarkable structural flexibility of simple copper(I) complexes, such as cuprous halides is covered, including numerous structural motifs that, when combined with different ligand systems, exhibit linear, trigonal planar or tetrahedral geometries. This work is an essential reference for inorganic and coordination chemists, as well as researchers working on catalysis, anticancer reagents, luminescence, fluorescence and photophysical aspects.
