[PDF] The Method Development For Synthesizing Chiral Ccc Nhc Zr Pincer Complexes eBook

Author : Amarraj Chakraborty
Publisher :
Page : 82 pages
File Size : 49,25 MB
Release : 2015
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ISBN :

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There are numerous classes of N-heterocyclic carbenes (NHCs) that have been synthesized since the discovery of stable NHCs in 1988. Their application as ligands in metal complexes has received much attention because of their strong sigma-donor and poor pi-acceptor properties. Within these NHC metal complexes, we are interested in studying zirconium metal complexes with pincer NHC ligands. Recently, achiral CCC-NHC pincer zirconium complexes were synthesized and their catalytic activity in intramolecular hydroamination of aminoalkenes were reported. Herein is reported new reaction conditions which yield pure, chiral CCC-NHC Zr pincer mono(amido) dibromo complex. The enantiopure crystal structure of the same complex is reported. Attempts to synthesize chiral CCC-NHC Zr pincer bis- and tris- amido complexes with the iodo salt of the ligand precursor are summarized. Moreover, syntheses of chiral bis(imidazolinium) ligand precursors with different counter anions are reported with optimized reaction conditions.

Author : Gopalakrishna Akurathi
Publisher :
Page : 177 pages
File Size : 31,54 MB
Release : 2016
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The first stable "free" N-heterocyclic carbene (NHC) was isolated in 1991, since then many classes of NHCs were synthesized and isolated. N-heterocyclic carbene ligands have become a common ligand in the synthesis of metal complexes, due to their strong [Sigma]-donation with poor [pi]-acceptor ability. Among all the NHC metal complexes, Hollis group was interested in exploring CCC-NHC pincer complexes. In 2005, Hollis and co-workers synthesized and isolated first achiral CCC-NHC zirconium pincer amido complex and studied its catalytic ability to perform intramolecular hydroamination of aminoalkenes. Later, Hollis group designed and developed new NHCs with a saturated chiral backbone, and used these new ligands to generate a new series of metal complexes. This dissertation is focused on the design, synthesis and characterization of several chiral bi-dentate NHC ligands with varying substituents on the backbone. These NHC ligands were used to synthesize several chiral mono, bis and tris amido CCC-NHC zirconium pincer complexes. Further, transmetallation to cobalt complexes were achieved. Intramolecular hydroamination was measured for several chiral bis and tris amido CCC-NHC pincer zirconium catalysts. Variants of these catalytic systems were generated with differing steric hinderance and electronic structure. The enantioselectivity of these novel new molecules were studied.

Author : Tyler Owen Howell
Publisher :
Page : 97 pages
File Size : 34,25 MB
Release : 2014
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ISBN :

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Methodologies for expanding the architectural diversity of CCC-N-heterocyclic carbene (NHC) pincer ligand precursors and transition metal complexes have been developed for the production of more efficient catalyst, which will be employed in the synthesis of pharmaceuticals. An efficient route for the synthesis and isolation of bis-1,3-(3'-aryl-N-heterocycl-1'-yl)arenes has been established, and preliminary data for metalation and transmetalation of a N, N'-diaryl imidazolium salt has been acquired. Additionally, a proficient methodology for the synthesis of mixed, unsymmetrical CCC-NHC pincer ligand precursors has been discovered, and preliminary data for mixed, unsymmetrical transition metal complexes is also included. These methodological expansions will lead to more efficient catalyst that decrease the expenditure of energy required for the synthesis of pharmaceuticals, thus making their synthesis more favorable for the environment and their price more affordable for consumers.

Author : David Morales-Morales
Publisher : Elsevier
Page : 467 pages
File Size : 25,38 MB
Release : 2011-08-11
Category : Science
ISBN : 0080545157

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Pincer complexes are formed by the binding of a chemical structure to a metal atom with at least one carbon-metal bond. Usually the metal atom has three bonds to a chemical backbone, enclosing the atom like a pincer. The resulting structure protects the metal atom and gives it unique properties.The last decade has witnessed the continuous growth in the development of pincer complexes. These species have passed from being curiosity compounds to chemical chameleons able to perform a wide variety of applications. Their unique metal bound structures provide some of the most active catalysts yet known for organic transformations involving the activation of bonds. The Chemistry of Pincer Compounds details use of pincer compounds including homogeneous catalysis, enantioselective organic transformations, the activation of strong bonds, the biological importance of pincer compounds as potential therapeutic or pharmaceutical agents, dendrimeric and supported materials. * Describes the chemistry and applications of this important class of organometallic and coordination compounds* Covers the areas in which pincer complexes have had an impact* Includes information on more recent and interesting pincer compounds not just those that are well-known

Author : Paul Jerome Kelley
Publisher :
Page : 148 pages
File Size : 11,6 MB
Release : 2010
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Abstract: The recently reported methodology for concomitant triple C-H activation of a CCC-NHC pincer ligand precursor followed by transmetallation to late transition metals has been extended to include nickel. A very faint solid state fluorescence has been collected for the complexes reported. X-ray structural analysis of a representative compound exhibits a distorted square planar geometry. Issues with rapid halogen exchange have been found in some cases indicating increased liability of the halide ligand uncommon in comparable systems.

Author : Gerard van Koten
Publisher : Springer
Page : 363 pages
File Size : 20,58 MB
Release : 2012-09-17
Category : Science
ISBN : 3642310818

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Gerard van Koten: The Mono-anionic ECE-Pincer Ligand - a Versatile Privileged Ligand Platform: General Considerations.- Elena Poverenov, David Milstein: Non-Innocent Behavior of PCP and PCN Pincer Ligands of Late Metal Complexes.- Dean M. Roddick: Tuning of PCP Pincer Ligand Electronic and Steric Properties.- Gemma R. Freeman, J. A. Gareth Williams: Metal Complexes of Pincer Ligands: Excited States, Photochemistry, and Luminescence.- Davit Zargarian, Annie Castonguay, Denis M. Spasyuk: ECE-Type Pincer Complexes of Nickel.- Roman Jambor and Libor Dostál: The Chemistry of Pincer Complexes of 13 - 15 Main Group Elements.- Kálmán J. Szabo: Pincer Complexes as Catalysts in Organic Chemistry.- Jun-ichi Ito and Hisao Nishiyama: Optically Active Bis(oxazolinyl)phenyl Metal Complexes as Multi-potent Catalysts.- Anthony St. John, Karen I. Goldberg, and D. Michael Heinekey: Pincer Complexes as Catalysts for Amine Borane Dehydrogenation.- Dmitri Gelman and Ronit Romm: PC(sp3)P Transition Metal Pincer Complexes: Properties and Catalytic Applications.- Jennifer Hawk and Steve Craig: Physical Applications of Pincer Complexes.

Author : Walter Kaminsky
Publisher : Wiley-VCH
Page : 0 pages
File Size : 12,18 MB
Release : 2006-08-18
Category : Technology & Engineering
ISBN : 9783527317424

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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.

Author : Kálmán J. Szabó
Publisher : John Wiley & Sons
Page : 389 pages
File Size : 49,77 MB
Release : 2014-06-10
Category : Science
ISBN : 3527681337

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This new book on this hot topic summarizes the key achievements for the synthesis and catalytic applications of pincer and pincer-type complexes, providing readers with the latest research highlights. The editors have assembled an international team of leaders in the field, and their contributions focus on the application of various pincer complexes in modern organic synthesis and catalysis, such as C-C and C-X bond forming reactions, C-H bond functionalization, and the activation of small molecules, as well as asymmetric catalysis. A must-have for every synthetic chemist in both academia and industry intending to develop new catalysts and improved synthetic protocols.