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The research covered in this thesis involves studying and understanding the behavior of bifunctional ligands, specifically imidazolylphoshines. The major field of study is reaction of cyclopentadienyl ruthenium complexes with olefins, namely alkene isomerization. In these complexes, the basic nitrogen of the imidazolylphosphine is thought to deprotonate coordinated alkene intermediates reversibly, facilitating isomerization of terminal alkenes to yield internal alkenes selectively. The CpRu alkene isomerization catalyst is capable of moving double bonds as far as 30 positions; further mechanistic studies in presence of deuterium labeling as a tool, has led to development of hydrogen deuterium exchange of olefins at allylic positions. This finding supports the proposed mechanism and provides and outstanding deuteration at positions accessible by isomerization. The alkene isomerization catalyst can be used in a two-phase setting where the catalyst is dissolved in the organic layer and the non-toxic, non-flammable isotopic source (D2O) is immiscible with the organic layer. Using biphasic settings one can literally wash out reactive protons on the substrate without using organic solvents. In order to control high activity of alkene isomerization catalyst in absence of steric bulk provided by the substrate, bulkier phosphine ligands were synthesized and the activity of their metal complexes toward linear olefins was investigated. As a result, a family of catalysts that is capable of isomerizing unsubstituted linear alkenes to various mixtures have been established, where one can choose a complex to fit the needs of the process at hand. Further investigation with terminal alkenes bearing functional groups can be carried out to investigate whether mono-isomerization will still be the major transformation taking place, which is expected to give access to high-value 2-alkenes. To provide easy product-catalyst separation and potential wider application, the first syntheses of polymer-supported imidazolylphophines were developed, and the alkene isomerization catalyst was thus immobilized on polystyrene-based Merrifield resin. Compared to the homogeneous catalyst, the immobilized catalysts give the same high (E)-selectivity and conversion in isomerizations of terminal olefins to internal olefins with very low metal leaching from the insoluble support. Furthermore, use of organic solvents can be excluded and isomerization can be carried out in neat liquid organic substrates.
A series of phosphines with different heterocycles (pyridine and imidazole) possessing different substituents (alkyl and aryl) were synthesized. The phosphine ligands were reacted with different metal precursors to from organometallic complexes which were applied to catalysis. This dissertation describes, part of the discovery process of a uniquely active and selective catalyst for alkene isomerization and the importance of heterocyclic ring in the ligand, enhancing the acceleration of the reaction to almost 11,000 times faster than a non-heterocyclic analog. Further investigation of the isomerization catalyst, as a catalyst for cycloisomerization of alkynols led to discovery of the fact that a related alkyne hydration catalyst, reported by Dan Lev in 2004, was broadly useful in cycloisomerization reactions leading to synthesis of both indoles and benzofurans. A series of allylpalladium(II) chloride bifunctional phosphine complexes were also synthesized and characterized and eventually applied as catalysts for aryl amination reactions. Finally, two mechanistically distinct approaches to anti-Markovnikov alkene hydration using bifunctional ligands are described, which show promise for further development.
CHAPTER 1. This chapter introduces the field of study and motivations steering the direction of development. The topics of catalysis and bifunctional catalysis are discussed. CHAPTER 2. This chapter describes the development of biaryl phosphines containing functionalization with a pendent base for use in gold catalyzed organic reactions. This chapter starts with development of synthetic methods for high efficiency in the synthesis of new iterations on the chemical structure. The use of high throughput screening for reaction discovery is discussed and the result from our trials is discussed. Evaluation of the different ligand candidates is done through NMR spectroscopic studies on two reactions. The first reaction studied is carboxylic acid addition to terminal alkynes. The second reaction studied is isomerization of alkynes. CHAPTER 3. This chapter describes the synthesis of hydrogen-bond-donor-functionalized ferrocenyl bisphosphines, and studies on the coordination chemistry of the novel bisphosphines with platinum and nickel. Development of the synthetic route to yielding the target compounds was necessary, and the major points of concern are discussed. Studies on the coordination chemistry of the ferrocenyl bisphosphines with platinum and nickel are discussed
Pincer-Metal Complexes: Applications in Catalytic Dehydrogenation Chemistry provides an overview of pincer-metal catalytic systems that transform hydrocarbons and their derivatives from an synthetic and mechanistic point-of-view. This book provides thorough coverage of the operating mechanisms and dehydrogenation catalyst compatibility in both functionalized and unfunctionalized hydrocarbon systems. In addition, it includes success stories of pincer-metal systems, as well as current and future challenges. The book is an ideal reference for researchers practicing synthetic organic chemistry, inorganic chemistry, organometallic chemistry and catalysis in academia and industry. In recent years there has been a surge in the research on hydrocarbon dehydrogenation catalytic systems that are compatible with polar substituents. This helps facilitate formulation of tandem processes that are not limited to hydrocarbon transformation but also to hydrocarbon functionalization in a single pot. Covers applications of pincer-metal complexes in organic transformations Includes pincer-group 8 and 9 metal complexes for alkane dehydrogenations Features a discussion of pincer-metal complexes for the dehydrogenation of functionalized hydrocarbons and electro-catalytic transformations
"Catalysis is truly an interdisciplinary field to which chemists, biologists, physicists, and engineers have made seminal contributions. This book aims to address the notably diverse topic of transition-metal catalysis in a single volume. The first half of the book is dedicated to the discrete and atomically precise metal complexes for homogeneous catalysis. Bimetallic, organometallic, and coordination complexes of early, late, and post-transition metals are described. Catalytic hydrogenation, oxidation, and coupling reactions are presented. The second half of the book focuses on three distinct types of nanomaterials: (1) zero- valent metallic nanoparticles, (2) titanium dioxide semiconductors, and (3) the porous coordination polymer known as the metal-organic framework. The chapters illustrate how deeply catalysis is influenced by other disciplines (e.g., coordination chemistry, bioinorganic chemistry, organometallic chemistry, computational chemistry, organic synthesis, photochemistry, materials science, environmental chemistry, green chemistry, and renewable energy). Advancements in these areas fuel the rapid growth of catalysis science. This book allows readers to reach a high-level of understanding in catalysis by learning from the perspectives of active practitioners. Unlike a textbook that provides a systematic, comprehensive, and historical education on the general topics of catalysis, this book offers critical case studies on select topics. Substantial emphasis is placed on the structural and fundamental properties that dictate catalyst performance, enabling readers to quickly understand and apply knowledge from cutting-edge studies and applications detailed within. This book can be utilized as a handbook, a textbook or textbook supplement, or a reference to guide future work"--
This book deals with polypyrazolylborates (scorpionates), a class of ligands known since 1966, but becoming rapidly popular with inorganic, organometallic and coordination chemists since 1986, because of their versatility and user-friendliness. They can be readily modified sterically and electronically through appropriate substitution on the pyrazole ring and on boron, and have led to a number of firsts in coordination chemistry (first stable CuCO complex, first monomeric MgR complex, and many other such firsts). Their denticity can range from two to four, their “Bite” can be adjusted, and additional coordinating sites can be added to the pyrazolyl rings. Over 170 different scorpionate ligands are known today, and some are published for the first time in this book.The author, Swiatoslaw Trofimenko, discovered and developed this ligand system and has written several reviews on the subject. The book is intended as a reference work, placing at the researcher's command practically all of the over 1500 references on the subject up, and into 1999, organized both according to the ligand type and according to the metal or metalloid being coordinated. It acquaints the reader with the special features of this ligand system and permits an assessment of what has been done in a given sub-area, and of which areas remain relatively unexplored. It presents procedures for ligand synthesis, and also covers their use in catalysis and in the modelling of biologically active substances.
Bifunctional organometallic catalysts offer unique opportunities for new and improved reactivity and selectivity. The combination of a metal's d electrons and a pendant base or acid in the vicinity of an organometallic active site leads to substantial improvement of reaction rate in many key reactions. Here we report a synthesis of the first example of an imidazol-2-yl substituted bifunctional N-heterocyclic carbene ligand (NHC) and its coordination to a variety of metals. The metal complexes have been characterized by IR, NMR, and X-ray crystallography. The catalytic activity of these new NHC-metal complexes in hydrogenation reactions (e.g. Oppenauer-type alcohol oxidation, ß-alkylation of secondary alcohols with primary alcohols, N-alkylation of amines with alcohols), hydroamination, and azide-alkyne cycloaddition reactions is described.
The first concise overview on the topic, spanning the spectrum from fundamentals to new application areas. The synthesis, kinetics and thermodynamics of these complexes are covered in detail, while much emphasis is placed on special properties such as gas transport, charge transport, catalysis and light-induced processes. Furthermore, the authors treat the actual working areas for new application methods. In all, a very helpful tool for polymer and materials scientists, as well as organic and physical chemists working in these fields.
In response to significant developments in sensor science and technology, this book offers insight into the various extended applications and developments of N4 macrocycle complexes in biomimetic electrocatalysis. Chapters are devoted to the chemistry, electronic and electrochemical properties of porphyrin- based polymetallated supramolecular redox catalysts and their applications in analytical and photoelectrochemical molecular devices; the use of porphyrins, phthalocyanines and related complexes as electrocatalysts for the detection of a wide variety of environmentally polluting and biologically relevant molecules; and the use of electropolymerized metalloporphyrin and metallophthalocyanine films as powerful materials for analytical tools, especially for sensing biologically relevant species.