Download or read book From the Reactivity of Pincer CCC Nickel Complexes to Catalysis with Simple Nickel Salts written by Gabriel Antonio Espinosa Martinez and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis and Initial Reactivity Studies of Nickel Complexes on a Pincer Scaffold written by Huy Dao and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Catalytic oxidation reactions are prevalent in the chemical industry. The catalysts are often made with expensive metals and the mechanism(s) by which they operate are not well known. Studies of small molecules can lead to better understanding of mechanisms and thus lead to better catalysis design. Work has also been performed in designing catalysts using less costly metals. Nickel is one such metal, as it is a congener of platinum and palladium, two costly metals used widely in catalysis. Ligands can be altered to influence electronic and steric properties of the metal complexes, thus affecting catalytic activity. This thesis addresses the modification of an SCS pincer ligand and the synthesis of new nickel-SCS pincer complexes. Pincers are tridentate ligands that bind at adjacent coplanar sites. The designation "SCS" refers to the atoms at the coordination sites. The nickel-pincer complexes in this work are built from 2,6- bis(alkylthiomethyl)bromobenzene skeletons, with the alkyl groups being altered. The work presented herein describes the synthesis and characterization of Ni(SCSiPr)Br, Ni(SCStBu)Br, Ni(SCSMe)OPh, and Ni(SCSMe)Me. The reactivity of Ni(SCSMe)Me was studied and found to form Ni(SCSMe)OPh when reacted with phenol. This showed that Ni(SCSMe)Me was able to deprotonate an acidic species to form a new complex. Ni(SCSMe)Me was also found to catalyze the oxidation of triphenylphosphine to triphenylphosphine oxide when dry O2 was introduced. Eight to ten turnovers were observed.

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 Nickel Catalysis in Organic Synthesis written by Sensuke Ogoshi and published by John Wiley & Sons. This book was released on 2020-03-09 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive reference to nickel chemistry for every scientist working with organometallic catalysts Written by one of the world?s leading reseachers in the field, Nickel Catalysis in Organic Synthesis presents a comprehensive review of the high potential of modern nickel catalysis and its application in synthesis. Structured in a clear and assessible manner, the book offers a collection of various reaction types, such as cross-coupling reactions, reactions for the activation of unreactive bonds, carbon dioxide fixation, and many more. Nickel has been recognized as one of the most interesting transition metals for homogeneous catalysis. This book offers an overview to the recently developed new ligands, new reaction conditions, and new apparatus to control the reactivity of nickel catalysts, allowing scientists to apply nickel catalysts to a variety of bond-forming reactions. A must-read for anyone working with organometallic compounds and their application in organic synthesis, this important guide: -Reviews the numerous applications of nickel catalysis in synthesis -Explores the use of nickel as a relatively cheap and earth-abundant metal -Examines the versatility of nickel catalysis in reactions like cross-coupling reactions and CH activations -Offers a resource for academics and industry professionals Written for catalytic chemists, organic chemists, inorganic chemists, structural chemists, and chemists in industry, Nickel Catalysis in Organic Synthesis provides a much-needed overview of the most recent developments in modern nickel catalysis and its application in synthesis.

Download or read book Nickel II Pincer Complexes Supported by 2 6 Bis 3 5 Ditolyl 2 Pyrrolyl Pyridine written by Abhijit Pramanik and published by . This book was released on 2015 with total page 95 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ni(II) pincer complexes are among the most important and useful compounds in homogeneous catalysis. Significant advancement has been made in this field in recent years. Many Ni(II) pincer complexes have been prepared and utilized in various catalytic reactions e.g. cross coupling reactions, C-H activation, carbon dioxide activation etc. Still, nickel(II) complexes supported by the pincer ligand with three nitrogen donors are relatively less explored and catalytic applications with those complexes are scarce in literature. This thesis describes the synthesis of a new pyrrolyl pyridine based pincer ligand and its Ni(II) complexes. The pyrrolyl pyridine pincer ligand, a relatively new class of dianionic, tridentate, nitrogen-based ligands in coordination chemistry, was prepared starting with a modified method for the synthesis of pyrrolyl pyridine. This modified procedure is simpler, less time consuming making it cheaper than the classical method and provides 2,6-bis(3,5-ditolyl-2-pyrrolyl)pyridine in good yields. Reaction of its potassium salt with Ni(OTf)2 resulted in three different stable nickel(II) pincer complexes. The novel nickel(II) pincer complexes were fully characterized by 1H NMR spectroscopy, 13C NMR spectroscopy, infrared spectroscopy and high resolution mass spectrometry. The X-ray crystal structures of the new ligand and metal complexes have been described.

Download or read book The Chemistry of Pincer Compounds written by David Morales-Morales and published by Elsevier. This book was released on 2011-08-11 with total page 467 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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

Download or read book Homogeneous Catalysis of Nickel Hydride Complexes Bearing a Bis phosphinite Pincer Ligand written by Sumit Chakraborty and published by . This book was released on 2012 with total page 175 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation is focused on the synthesis of well-defined nickel hydride complexes bearing a bis(phosphinite) pincer ligand (commonly known as a POCOP ligand) and utilities of these metal complexes in varieties of useful organic transformations. Aldehydes insert cleanly and selectively into the Ni-H bonds of (POCOP)NiH complexes to form nickel alkoxide complexes. These nickel alkoxide compounds further react with phenylsilane to regenerate (POCOP)NiH and produce silyl ethers. Based on these observations, an efficient and chemoselective hydrosilylation process has been developed utilizing nickel hydrides as catalysts. The process is highly compatible with varieties of functional groups in aldehydes. A nickel hydride complex with smaller substituents on the POCOP ligand proves to be more effective hydrosilylation catalyst. In case of ketones, partial hydrosilylation occurs. (POCOP)NiH complexes also react with CO2 to produce nickel formate complexes. When stoichiometric amounts of boranes are used, nickel hydrides are cleanly reformed. The use of catalytic amounts of nickel hydrides and excess of boranes reduces CO2 to the corresponding methanol derivatives. The initial reduction products can be further hydrolyzed to yield methanol. The overall transformation is comprised of three catalytic cycles. A catalyst with more bulky substituents on the phosphorus atoms of pincer ligand is a more effective catalyst than those containing smaller substituents. This phenomenon has been rationalized by invoking more favorable dihydridoborate adduct formation between less bulky nickel hydrides and boranes. One of such dihydridoborate adduct has been successfully isolated and its influence on the catalytic CO2 reduction has been demonstrated. (POCOP)NiH complexes have been found be active catalysts for the decomposition of formic acid to release dihydrogen. When the kinetics the reaction is monitored by in-situ IR spectroscopy, a unique sigmoidal pattern is observed. Several mechanistic possibilities such as heterogeneity, cooperativity, and formation of other reactive intermediates have been experimentally tested to understand the unusual kinetic behavior. A mechanistic investigation pertaining to NiH-catalyzed isomerization of terminal olefins such as 1-butene has been carried out. Two major pathways for olefin isomerization reaction, namely (a) metal hydride addition-elimination and (b) p-allyl metal hydride have been ruled out on the basis of reactivity studies of branched nickel butyl complex and labeling experiments. An H-atom transfer pathway has been proposed based on the radical inhibitor studies. In addition to the olefin isomerization, the branched nickel butyl complex isomerizes to the linear nickel butyl complex possibly via a unique intramolecular pathway. Nickel hydrides efficiently catalyze the cyanomethylation of aldehydes to produce ß-hydroxy nitriles. This reaction does not require an external base which is mandatory for other related systems. The (POCOP)Ni-CH2CN complex, a potential intermediate in this reaction, has been isolated and characterized. This compound reacts directly with benzaldehyde to produce the ß-hydroxy nitrile. The nickel alkoxide complexes that result from the insertion reaction between nickel hydrides and aldehydes, act as internal bases in this system. Varieties of aldehydes including base-sensitive aldehydes have been successfully coupled with acetonitrile using nickel hydride catalysts.

Download or read book The Organic Chemistry of Nickel written by P.W. Jolly and published by Elsevier. This book was released on 2012-12-02 with total page 417 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Organic Chemistry of Nickel, Volume II: Organic Synthesis describes the chemistry of the organonickel complexes and the use of nickel in organic synthesis. Composed of six chapters, this volume starts with discussions on the oligomerization, co-oligomerization, and polymerization of olefins, followed by short accounts of the mechanistically related isomerization and hydrogenation of olefins, as well as the hydrosilylation and hydrocyanation reactions. Chapter II examines the oligomerization of acetylene and substituted alkynes, the co-oligomerization of alkynes with olefins, the related oligomerization of allene, including a number of telomerization reactions involving alkynes or allenes. Chapters III and IV describe the oligomerization, co-oligomerization, and polymerization of butadiene and substituted 1,3-dienes. Chapter V explores the coupling of organic halides in the presence of stoichiometric amounts of zerovalent nickel complexes, and the nickel-catalyzed cross-coupling reaction between organic halides and Grignard reagents. Lastly, Chapter VI emphasizes the carbonylation of alkynes, olefins, and organic halides using nickel complexes. This book will be of great value to organic chemists and researchers who are interested in the application of nickel complexes to organic synthesis.

Download or read book Oxidative C C and C heteroatom Reactivity of High valent Nickel Complexes written by Sofia M. Smith and published by . This book was released on 2019 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nickel catalysts are commonly used for cross-coupling reactions such as Negishi, Kumada and Suzuki couplings. While Ni(0), Ni(I), and Ni(II) intermediates are most relevant in these transformations, Ni(III) and Ni(IV) species have also been recently proposed to play a role in catalysis. The formation of C-C and C-heteroatom bonds plays a fundamental role in organic transformations, and today cross-coupling reactions are one of the most powerful tools for the construction of new C-C bonds. However, limited examples exist of Ni-mediated C-heteroatom bond formation reactions, likely due to the difficulty of accessing high-valent organometallic Ni species that can undergo reductive elimination.One way to expand our knowledge of these C-C and C-heteroatom atom bond formation reactions is to look at the stabilization and destabilization effects of the high-valent nickel complexes. Studying these effects will help us determine the most efficient way in performing C-C and C-heteroatom atom bond formation reactions. Tetradentate pyridinophane ligands have been to stabilize uncommon high-valent organometallic nickel complexes. By varying the N-substituents, we are now able to probe the stabilization and destabilization effects that might play a crucial role in the C-C and C-heteroatom atom bond formation reactions.A series of nickel complexes were synthesized to probe the C-C and C-heteroatom atom bond reactivity using the Ni-dimethyl and -metallacycle complexes. These complexes were fully characterized and their reactivity was tested. The oxidative reactivity was studied by looking at a variety of oxidants which include dioxygen and hydrogen peroxide to probe any C-O bond formation. Interestingly, while the oxidation of the NiII metallacycle complexes with various oxidants led to exclusive C-C bond formation in very good yields, the use of O2 or H2O2 as oxidants led to appreciable amounts of C-O bond formation products, especially for an asymmetric pyridinophane ligand with one tosyl N-substituent. Moreover, cryo-ESI-MS studies strongly support the formation of several high-valent nickel species as key intermediates in this unprecedented aerobic Ni-mediated oxygenase-type chemistry.Lastly, the tetradentate pyridinophane ligands were used in two catalytic oxidation reactions, a hydroxylation and a chlorination reaction for unactivated alkanes. These catalytic oxidation reactions use mild oxidants such as hypohalites which are commercially available. All these reactions could have important implications in organic transformations.

Download or read book Organometallic Pincer Chemistry written by Gerard van Koten and published by Springer. This book was released on 2012-09-17 with total page 363 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Oxidative C C Bond Formation Reactivity of High Valent Nickel and Palladium Complexes written by Michael Benjamin Watson and published by . This book was released on 2017 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt: The development of both palladium and nickel catalysis over the past several decades has led to the ability to perform a multitude of C-C coupling, C-Heteroatom coupling, and C-H functionalization reactions. These reactions typically utilize a catalytic cycle involving Pd0/II/IV and Ni0/II. While using these types of catalytic cycles one can create a multitude of different hard to make bonds, it is always important to keep expanding what we view as potential catalytic intermediates to keep developing new cycles capable of new transformations. One such way to expand our knowledge of these catalytic cycles is to look at the oxidation states that are less commonly observed in catalysis. This typically involves PdI/III and NiI/III/IV. Studying these rare oxidation states allows us to determine if they have the potential to either take part in current catalytic cycles, or develop new ones that take advantage of these oxidation states. Our group has previously synthesized various PdIII and NiIII complexes with the support of N,N'- dialkyl-2,11-diaza[3.3](2,6)pyridinophane (RN4). This ligand has allowed for the isolation and characterization of these complexes that are typically seen as unstable letting us study their reactivity. First, we investigated the effects of ligand flexibility on the stabilization of PdIII complexes by synthesizing several ligands. The "flexible" ligands had a 1,4,7-triazacyclononane framework and the "rigid" ligands had a diazabicylononanone framework. Seeing that the flexible 1,4,7- triazacyclononane ligands seemed to be better at stabilizing the high valent palladium, we continued using it to synthesize organometallic nickel complexes. These complexes proved very easy to oxidize allowing NiII/III/IV oxidation states to be isolated and fully characterized. The oxidative reactivity was studied for these three nickel complexes looking at oxidative addition with organic halides, aerobic oxidation, and most interestingly photolysis that resulted in much faster reductive elimination from the NiIV species. Lastly, we investigated the ligand modifications that can be done to either stabilize or destabilize high valent NiIII species using a N,N'-dialkyl-2,11- diaza[3.3](2,6)pyridinophane ligand that was modified to observe the effect on differing amounts of steric bulk and electronic effects. Studying these rare high valent complexes is important so we can continue to expand the scope of what catalytic transformations we can use to improve our daily lives.

Download or read book Nickel and Iridium Pincer Complexes with Saturated Frameworks written by and published by . This book was released on 2014 with total page 49 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Trends in Organometallic Chemistry written by and published by . This book was released on 1999 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nickel Catalysis and Coordination Chemistry written by Yahya Albkuri and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Different metals and metal complexes have been used as catalysts in many industries such as commodity petrochemicals, fine and specialty chemicals, polymers, environmental services, agrochemicals and pharmaceuticals. Although these catalysts allow for increased reaction rates and selectivity, they can also be toxic, expensive and of limited supply (cf. Pt group metals). This has led researchers to the intensive study of first row metal catalysts, with nickel standing out as the most widely studied to date. As found for other first row metal catalysts, nickel's easy access to oxidation states 0-3 allows for a number of different one- and two-electron mechanisms and novel transformations. In Chapter 2 we use a phosphine-free, tridentate N,N,N ligand to generate an active catalyst for the C-N cross-coupling reaction of aryl halides with amines. The catalyst demonstrated excellent turnover numbers (up to 484) for the amination reactions that are proposed to proceed through a Ni(I)-Ni(III) cycle. In Chapter 3 we investigate the Ni coordination chemistry of a biomimetic SNS thiolate ligand. Protonation of the Ni bis(thiolate) complex, Ni(-SNS)2, removes one SNS ligand, affording crystals of a thiolate-bridged dimer dication, {[Ni(--SNS)]2}2+ that exhibits unique anionic tridentate ligand dynamics. Dissolving these crystals, even in weakly-coordinating solvents such as dichloromethane, gives a mixture of 'naked' Ni2+ and paramagnetic, trinuclear {[Ni(--SNS)2]2Ni}2+. Although this equilibrium lies far to the right (no diamagnetic dication visible in NMR), addition of ancillary ligands proceeds smoothly to provide several mono- and dinuclear Ni thiolate products, [Ni-SNS)L]n - potential bifunctional catalysts for further studies. In Chapter 4 we demonstrate using chemical and electrochemical techniques that one-electron reduction of Ni(-SNS)2 triggers quantitative imine C-C bond coupling, forming [Ni(S2N2)]- with a redox-active ligand. Spectroelectrochemical studies indicated reversible oxidation and reduction steps give three stable redox states, ([Ni(S2N2)]0/-/2-), that were characterized by NMR, EPR and UV-Vis spectroscopy, X-ray diffraction and computational chemistry. While the Ni(0) dianion (and not the Ni(I) anion) reacted reversibly with phenol and carbon dioxide, results from Chapter 5 showed that reactions with strong electron-acceptor fluoroalkenes proceeded more cleanly with the Ni(I) anion. The latter reactions afforded a mixture of fluoroalkenyl and fluoroalkyl products resulting from C-F bond activation and electron transfer/H atom abstraction, respectively. In Chapter 6 we discuss our results in the context of the current state of the art and suggest some avenues for future development.

Download or read book Modern Organonickel Chemistry written by Yoshinao Tamaru and published by John Wiley & Sons. This book was released on 2006-03-06 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt: Organonickel chemistry plays an increasingly important role in organic chemistry, and interest in this topic is now just as keen as in organopalladium chemistry. While there are numerous, very successful books on the latter, a book specializing in organonickel chemistry is long overdue. Edited by one of the leading experts in the field, this volume covers the many discoveries made over the past 30 years, and previously scattered throughout the literature. Active researchers working at the forefront of organonickel chemistry provide a comprehensive review of the topic, including cross-coupling reactions, asymmetric synthesis and heterogeneous catalysis reaction types. A must-have for both organometallic chemists and synthetic organic chemists.

Download or read book N Heterocyclic Carbenes written by Silvia Diez-Gonzalez and published by Royal Society of Chemistry. This book was released on 2016-11-04 with total page 637 pages. Available in PDF, EPUB and Kindle. Book excerpt: In less than 20 years N-heterocyclic carbenes (NHCs) have become well-established ancillary ligands for the preparation of transition metal-based catalysts. This is mainly due to the fact that NHCs tend to bind strongly to metal centres, avoiding the need of excess ligand in catalytic reactions. Also, NHC‒metal complexes are often insensitive to air and moisture, and have proven remarkably resistant to oxidation. This book showcases the wide variety of applications of NHCs in different chemistry fields beyond being simple phosphine mimics. This second edition has been updated throughout, and now includes a new chapter on NHC‒main group element complexes. It covers the synthesis of NHC ligands and their corresponding metal complexes, as well as their bonding and stereoelectronic properties and applications in catalysis. This is complemented by related topics such as organocatalysis and biologically active complexes. Written for organic and inorganic chemists, this book is ideal for postgraduates, researchers and industrialists.

Download or read book Synthesis Characterization and Catalytic Reactivity of First row Transition Metal CCC Pincer Complexes written by Bailey Jeanne Jackson and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: