New Sterically-bulky Nitrogen-donor Ligands for Organometallic Chemistry PDF Download

Author: Joseph Alan Schmidt
Publisher:
ISBN:
Category :
Languages : en
Pages : 624

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Author: Jason Douglas Masuda
Publisher:
ISBN:
Category :
Languages : en
Pages : 324

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Author: Giuliano GIAMBASTIANI
Publisher: Springer Science & Business Media
ISBN: 9400706960
Category : Science
Languages : en
Pages : 272

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Book Description
Olefin Upgrading Catalysis by Nitrogen-based Metal Complexes II: State-of-the-art and Perspectives provides a critical review of the state-of-the-art developments in industrially relevant processes connected to efficient and selective olefin upgrading. Specific attention is devoted to catalysts containing imine- and amine-based ligands. All the chapters in this book have been designed to provide a systematic account of the vast amount of information available for this type of catalyst as well as to highlight the factors that ultimately control the catalyst’s performance and productivity. A comprehensive panorama of catalyst precursors is presented, spanning from group 10 α-diimine complexes and iron and cobalt 2,6-bis(imino)pyridine derivatives, to vanadium, chromium, titanium, zirconium and lanthanide complexes supported by nitrogen-containing ligands. The authors of this collective work are currently involved in the development of imine-based catalysts for efficient and selective olefin upgrading and the majority of them have dedicated most of their scientific career to this important field. In writing this book, their major goal is to transfer as many ideas and experiences as possible to the global audience of scientists engaged in this area of research.

Author: Giuliano Giambastiani
Publisher: Springer Science & Business Media
ISBN: 9048138159
Category : Science
Languages : en
Pages : 296

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This book highlights key advances that have occurred in the field of olefin conversion in recent years. The role of homogenous transition metal catalysts which contain an imine functionality is emphasized; their potential applications in the processing and upgrade of olefins to a wide variety of commodity products of very high industrial value is also explored. On the threshold of the fiftieth anniversary of the Noble Prize to Ziegler and Natta, this book gives a critical summary of the state of the art developments in the fascinating and rapidly developing field of the olefin polymerization, oligomerization, and co-polymerization catalysis.

Author: Nathan C. Duncan
Publisher:
ISBN:
Category : Chelates
Languages : en
Pages : 237

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The development of ligands for asymmetric catalysis has been a focal point in our research group. Tridentate nitrogen ligands have been used in a variety of asymmetric catalytic reactions. Of these, the 2,6-bis-pyrazolylpyridine class of ligands has found only limited use, due to difficulties in the normal synthetic route that limit the synthesis of ligands with bulky chiral groups attached to the pyrazole rings. The chiral derivatives that have been used in catalysis have shown modest to poor results, due in part to limitations in the synthesis of these ligands that prevent the development of bulky, chiral ligands. A new synthetic route has been developed using 2,6-bis-hydrazinopyridine (BHP). This route allows for a facile, one-pot synthesis of 2,6-bis-pyrazolylpyridines that is not limited by the bulkiness of the groups that become attached to the pyrazole ring. The primary focus of this research has been the development of new chiral 2,6-bis-pyrazolylpyridines and an investigation into the limitations of steric bulk on chelation ability in this class of ligands. For this purpose, several novel chiral ligands have been synthesized. The effect of sterics and electronics on the regioselectivity of the formation of the pyrazole ring was also studied in order to develop more regioselective routes to this class of ligands. The new bulky pyrazolylpyridine ligands that have been synthesized using this route have also been tested for the ability to sucessfully coordinate a transition metal. This study lead to a better understanding of the limitations the size of the substitutents attached to pyrazole ring have on the ligands' ability to chelate metals. While BHP was developed primarily for the synthesis of the 2,6-bis-pyrazolylpyridine class of ligands, its use has now been expanded to the synthesis of other classes of tridentate-nitrogen ligands, many of which would be diffiuclt or impossible to synthesize through any other route. Using this new methodolgy, the syntheses of two novel classes of ligands, each with unique properties, the 2,6-bis-hydrazonopyridines and 2,6-bis-indazolylpyridines, have now been accomplished. The previously unknown 2,6-bis-indazolylpyridine class of ligands is offers the possibility to synthesize more robust catalysts than is possible using the bis-pyrazole ligands because of the electronic nature of the indazole ring.

Author: Andrew Jolleys
Publisher:
ISBN:
Category :
Languages : en
Pages :

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The reaction of imidoyl chlorides IMC1-9 with lithium [beta]-diketiminates Li(BDKx) (x = iPr, iPr2, tBu, Me3, iPr2/OMe) yields [beta]-triketimines L1-16 which represent a new class of facially-coordinating neutral tridentate nitrogen ligands. The synthetic route is highly modular, allowing for wide variation of substitution patterns and thus fine control over the steric demands of the ligands. In all but two examples (L11 and L12) the [beta]-triketimines exist in solution either solely as their enamine-diimine tautomers, or as equilibrium mixtures of the two. The processes of solution-phase equilibration have been studied by NMR spectroscopy. The molecular structures of L1, L10 and L11 are presented, and for each case a single differing tautomer or isomer is observed exclusively. The majority of the ligands yield fac-(L)M(CO)3 adducts upon reaction with group 6 metal carbonyls, except in cases of extreme steric bulk. The [beta]-triketimines are relatively weak [sigma]-donors, as determined by the CO stretching frequencies in (L)M(CO)3. The molecular structures of the isomorphous pair (L1)M(CO)3 (M = Cr, Mo) reveal porous infinite network arrangements generated by aryl-aryl and CH--OC interactions. The direct reaction of [beta]-triketimines with ZnCl2 in most cases gives [(L)ZnCl]2[Zn2Cl6] complexes, whilst in the presence of either NaBArF4 or AgOTf the corresponding [(L)ZnCl][BArF4] and [(L)ZnCl][OTf] species are obtained. The complexes invariably feature four-coordinate, cationic zinc centres, except in the case of [([eta]4-L16)ZnCl][BArF4] where a five-coordinate complex is formed by additional coordination of a single ligand methoxy group. The reaction of [(L)ZnCl][BArF4] with TlOEt yielded not the desired zinc alkoxides, but novel [(L)Tl][BArF4] complexes, the solid-state structures of which display thallophilic interactions. The direct reaction of L8 and L10-12 with NiBr2(DME) gives the corresponding four-coordinate [(L)NiBr]2[NiBr4] complexes, whereas the products obtained with weakly-coordinating anions are dependent on the ligand bulk and the size of the anion. With the large BArF4- ion the formation of the five-coordinate dimeric [{(L)Ni([mu]-Br)}2][BArF4]2 (L = L1, L3, L5, L7, L8, L12) is strongly favoured, except for the bulkiest ligands where the four-coordinate [(L)NiBr][BArF4] (L = L10, L11) are obtained. The smaller triflate ion generally favours the formation of [(L)NiBr][OTf] (L1, L8, L10-12) except in the case of [{(L)Ni([mu]-Br)}2][OTf]2 (L = L3, L5). L15 and L16 act invariably as tetradentate donors to Ni(II), yielding the five-coordinate [([eta]4-L)NiBr][X] (X = BArF4, OTf) and [([eta]4-L16)NiBr]2[NiBr4]. The very bulky L6 coordinates in a bidentate mode to Ni(II), giving the four-coordinate [([eta]2-L6)NiBr(THF)][BArF4] and ([eta]2-L6)NiBr2. [{(L)Ni([mu]-Br)}2][BArF4]2 (L = L3, L5, L7), [{(L)Ni([mu]-Br)}2][OTf]2 (L = L3, L5), [([eta]2-L6)NiBr(THF)][BArF4] and ([eta]2-L6)NiBr2 show moderate catalytic activity for the polymerisation of ethylene in combination with MAO. All other complexes tested are inactive, either due to steric factors or the inability of certain [beta]-triketimines to support catalytically active square-planar Ni(II) species. A proposed mechanism for catalyst activation is presented. Elastomeric polyethylene of very low crystallinity is obtained, with branching rates in the range 43-84 branches per 1000 C. 13C NMR spectroscopy reveals the presence of all short-chain branches from methyl to hexyl, as well as longer branches and pairs of branches.

Author: Marine Desage-El Murr
Publisher: John Wiley & Sons
ISBN: 3527348506
Category : Science
Languages : en
Pages : 373

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Redox-Active Ligands Authoritative resource showcasing a new family of ligands that can lead to better catalysts and promising applications in organic synthesis Redox-Active Ligands gives a comprehensive overview of the unique features of redox-active ligands, describing their structure and synthesis, the characterization of their coordination complexes, and important applications in homogeneous catalysis. The work reflects the diversity of the subject by including ongoing research spanning coordination chemistry, organometallic chemistry, bioinspired catalysis, proton and electron transfer, and the ability of such ligands to interact with early and late transition metals, lanthanides, and actinides. The book is divided into three parts, devoted to introduction and concepts, applications, and case studies. After the introduction on key concepts related to the field, and the different types of ligands and complexes in which ligand-centered redox activity is commonly observed, mechanistic and computational studies are described. The second part focuses on catalytic applications of redox-active complexes, including examples from radical transformations, coordination chemistry and organic synthesis. Finally, case studies of redox-active guanidine ligands, and of lanthanides and actinides are presented. Other specific sample topics covered include: An overview of the electronic features of redox-active ligands, covering their historical perspective and biological background The versatility and mode of action of redox-active ligands, which sets them apart from more classic and tunable ligands such as phosphines or N-heterocyclic carbenes Preparation and catalytic applications of complexes of stable N-aryl radicals Metal complexes with redox-active ligands in H+/e- transfer transformations By providing up-to-date information on important concepts and applications, Redox-Active Ligands is an essential reading for researchers working in organometallic and coordination chemistry, catalysis, organic synthesis, and (bio)inorganic chemistry, as well as newcomers to the field.

Author: Jamie Hicks
Publisher: Springer
ISBN: 9811029059
Category : Science
Languages : en
Pages : 214

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This thesis describes the synthesis and characterization of numerous metal-metal bonded complexes that are stabilized by extremely bulky amide ligands. It provides a comprehensive overview of the field, including discussions on groundbreaking complexes and reactions, before presenting in detail, exciting new findings from the PhD studies. The thesis appeals to researchers, professors and chemistry undergraduates with an interest in inorganic and/or organometallic chemistry.

Author: LeGrande M. Slaughter
Publisher: Springer
ISBN: 3319137220
Category : Science
Languages : en
Pages : 292

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The series Topics in Current Chemistry presents critical reviews of the present and future trends in modern chemical research. The scope of coverage is all areas of chemical science including the interfaces with related disciplines such as biology, medicine and materials science. The goal of each thematic volume is to give the non-specialist reader, whether in academia or industry, a comprehensive insight into an area where new research is emerging which is of interest to a larger scientific audience. Each review within the volume critically surveys one aspect of that topic and places it within the context of the volume as a whole. The most significant developments of the last 5 to 10 years are presented using selected examples to illustrate the principles discussed. The coverage is not intended to be an exhaustive summary of the field or include large quantities of data, but should rather be conceptual, concentrating on the methodological thinking that will allow the non-specialist reader to understand the information presented. Contributions also offer an outlook on potential future developments in the field. Review articles for the individual volumes are invited by the volume editors. Readership: research chemists at universities or in industry, graduate students.

Author: Mark Stradiotto
Publisher: John Wiley & Sons
ISBN: 1118839811
Category : Science
Languages : en
Pages : 448

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The design of ancillary ligands used to modify the structural and reactivity properties of metal complexes has evolved into a rapidly expanding sub-discipline in inorganic and organometallic chemistry. Ancillary ligand design has figured directly in the discovery of new bonding motifs and stoichiometric reactivity, as well as in the development of new catalytic protocols that have had widespread positive impact on chemical synthesis on benchtop and industrial scales. Ligand Design in Metal Chemistry presents a collection of cutting-edge contributions from leaders in the field of ligand design, encompassing a broad spectrum of ancillary ligand classes and reactivity applications. Topics covered include: Key concepts in ligand design Redox non-innocent ligands Ligands for selective alkene metathesis Ligands in cross-coupling Ligand design in polymerization Ligand design in modern lanthanide chemistry Cooperative metal-ligand reactivity P,N Ligands for enantioselective hydrogenation Spiro-cyclic ligands in asymmetric catalysis This book will be a valuable reference for academic researchers and industry practitioners working in the field of ligand design, as well as those who work in the many areas in which the impact of ancillary ligand design has proven significant, for example synthetic organic chemistry, catalysis, medicinal chemistry, polymer science and materials chemistry.