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Mechanistic Insights Into Late Transition Metal Catalyzed Olefin Hydrosilylation And Synthesis Of New N Heterocyclic Carbene And Dinuclear Complexes
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Book Synopsis Mechanistic Insights Into Late Transition Metal-Catalyzed Olefin Hydrosilylation and Synthesis of New N-Heterocyclic Carbene and Dinuclear Complexes by : Korbinian Riener
Download or read book Mechanistic Insights Into Late Transition Metal-Catalyzed Olefin Hydrosilylation and Synthesis of New N-Heterocyclic Carbene and Dinuclear Complexes written by Korbinian Riener and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis N-Heterocyclic Carbenes in Transition Metal Catalysis by : Frank Glorius
Download or read book N-Heterocyclic Carbenes in Transition Metal Catalysis written by Frank Glorius and published by Springer. This book was released on 2007-02-05 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this book leading experts have surveyed major areas of application of NHC metal complexes in catalysis. The authors have placed a special focus on nickel- and palladium-catalyzed reactions, on applications in metathesis reactions, on oxidation reactions and on the use of chiral NHC-based catalysts. This compilation is rounded out by an introductory chapter and a chapter dealing with synthetic routes to NHC metal complexes.
Book Synopsis Aryl-Substituted Imino-N-Heterocyclic Carbene Complexes Of Late Transition Metals by : Anna Candace Badaj
Download or read book Aryl-Substituted Imino-N-Heterocyclic Carbene Complexes Of Late Transition Metals written by Anna Candace Badaj and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Science of Synthesis: N-Heterocyclic Carbenes in Catalytic Organic Synthesis Vol. 2 by : Steven Nolan
Download or read book Science of Synthesis: N-Heterocyclic Carbenes in Catalytic Organic Synthesis Vol. 2 written by Steven Nolan and published by Thieme. This book was released on 2017-06-14 with total page 816 pages. Available in PDF, EPUB and Kindle. Book excerpt: The field of N-heterocyclic carbenes, whether in transition-metal catalysis or organocatalysis, is rapidly evolving towards applications, but is also still very active on the catalyst development front. Significant advances have been made over the past two decades and the development of these reactions has dramatically improved the efficiency of organic synthesis. N-Heterocyclic carbene based catalysts are now widely applied in the area of synthesis of both natural products and therapeutic agents. "Science of Synthesis: N-Heterocyclic Carbenes in Catalytic Organic Synthesis" presents the most commonly used and significant metal- or non-metal-catalyzed reactions for modern organic synthesis. The basic principles and current state-of-the-art of the methods are covered. Scope, limitations, and mechanism of these reactions are discussed and key experimental procedures are included. Typical examples of target synthesis are often provided to show the utility and inspire further applications.
Book Synopsis Olefin Polymerization by : Walter Kaminsky
Download or read book Olefin Polymerization written by Walter Kaminsky and published by Wiley-VCH. This book was released on 2006-08-18 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Nickel and Cobalt-catalyzed Hydrofunctionalization Reaction of Alkene by : Balaram Raya
Download or read book Nickel and Cobalt-catalyzed Hydrofunctionalization Reaction of Alkene written by Balaram Raya and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Organic reactions catalyzed by metal complexes are an effective way to improve atom economy and environmental friendliness for many synthetic transformations. Among the various synthetic transformations, hydrosilylation reaction has huge industrial applications for manufacturing consumer goods. The alkylsilanes from alkene hydrosilylation are widely used as raw materials in manufacturing silicon rubbers, molding implants and adhesive. The hydrosilylation reactions can also produce various organosilicon reagents, which are used in fine chemical synthesis for stereospecific oxidation and cross coupling reaction. Over the long decades, numerous reports on metal-catalyzed hydrosilylations include the use of platinum, palladium, rhodium, ruthenium, iridium, lanthanides and actinides, early transition metals, iron, cobalt to a limited extent nickel. This work has shown that readily accessible (iPrPDI)CoCl2 reacts with 2 equivalents NaEt3BH at -78 oC in toluene to generate a catalyst that effects highlyselective anti-Markovnikov hydrosilylation of the terminal double bond in alkene, 1,3- and 1,4-dienes. Primary and secondary silanes such as PhSiH3, Ph2SiH2 and PhSi(Me)H2 react with a broad spectrum of dienes without affecting the configuration of the other double bond. A slight modification of the reaction conditions using a less reactive silane (OEt)2Si(Me)H leads to unprecedented and highly selective reduction of the terminal double bond with no contamination from the silane or reduction products of the more substituted double bond. The major limitation for cobalt catalyzed hydrosilylation reaction using redox active PDI ligand is its terminal selectivity. However, this active catalyst did not work for 1,1-disubstituted alkenes. In this connection, we also observed efficient cobalt catalyst system for hydrosilylation of 1,1-disubstituted alkenes using chelating phosphine ligand at room temperature, which is able to do hydrosilylation for numerous substrates such as alkene, vinyl arene, conjugated diene, 1,4-skipped diene and 1,1-disubstituted alkenes. Carbocyclizations of a,¿-p-systems are extremely important and useful reactions for the synthesis of a variety of carbocyclic and heterocyclic compounds. Although metal catalyzed cyclization has been long known, controlling the selectivity (chemo- and regio-) remains an important challenge in this field. Nickel complexes have been known to be specifically effective for cyclic homo-and co-oligomerization of alkenes, alkynes and dienes. During the past few years, through an approach that relied mostly on mechanistic insights and systematic examination of ligand effects, RajanBabu group has discovered a number of protocols for Ni(II)-catalyzed heterodimerization reactions of vinylarenes, selected 1,3-dienes and strained olefins. Substitution of one of the phenyl groups of triphenylphosphine with a 2-benzyloxy-(e.g., L18), 2-benzyloxy-methyl-(L19) or 2-benzyloxyethyl-(L20) phenyl moiety results in a set of simple ligands, which exhibit strikingly different behavior in various nickel (II)-catalyzed olefin dimerization reactions including related cycloisomerization of 1,6-dienes. Nickel(II)-catalyzed cycloisomerization of 1,6-dienes into methylenecyclopentanes, a reaction mechanistically related to the other heterodimerization reactions, is also uniquely affected by nickel(II) complexes of L18, but not of L19 or L20. In an attempt to prepare authentic samples of the methylenecyclohexane products, nickel(II) complexes of N-heterocyclic carbene ligands were examined. In contrast to the phosphine, which gives the methylenecyclopentanes, methylenecyclohexanes are the major products in the N-heterocyclic carbine ligated nickel (II)-mediated reaction. This dissertation discusses the ligand effect on hydrofuctionalization of alkenes using nickel or cobalt metal complexes.
Book Synopsis Science of Synthesis: N-Heterocyclic Carbenes in Catalytic Organic Synthesis Vol. 1 by : Steven Nolan
Download or read book Science of Synthesis: N-Heterocyclic Carbenes in Catalytic Organic Synthesis Vol. 1 written by Steven Nolan and published by Thieme. This book was released on 2017-06-14 with total page 807 pages. Available in PDF, EPUB and Kindle. Book excerpt: The field of N-heterocyclic carbenes, whether in transition-metal catalysis or organocatalysis, is rapidly evolving towards applications, but is also still very active on the catalyst development front. Significant advances have been made over the past two decades and the development of these reactions has dramatically improved the efficiency of organic synthesis. N-Heterocyclic carbene based catalysts are now widely applied in the area of synthesis of both natural products and therapeutic agents. Science of Synthesis: N-Heterocyclic Carbenes in Catalytic Organic Synthesis presents the most commonly used and significant metal- or non-metal-catalyzed reactions for modern organic synthesis. The basic principles and current state-of-the-art of the methods are covered. Scope, limitations, and mechanism of these reactions are discussed and key experimental procedures are included. Typical examples of target synthesis are often provided to show the utility and inspire further applications.
Book Synopsis Metal Catalysts in Olefin Polymerization by : Zhibin Guan
Download or read book Metal Catalysts in Olefin Polymerization written by Zhibin Guan and published by Springer Science & Business Media. This book was released on 2009-03-31 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polyolefin is a major industry that is important for our economy and impacts every aspect of our lives. The discovery of new transition metal-based catalysts is one of the driving forces for the further advancement of this field. Whereas the classical heterogeneous Ziegler-Natta catalysts and homogeneous early transition metal metallocene catalysts remain the workhorses of the polyolefin industry, in roughly the last decade, tremendous progress has been made in developing non-metallocene-based olefin polymerization catalysts. Particularly, the discovery of late transition metal-based olefin polymerization catalysts heralds a new era for this field. These late transition metal complexes not only exhibit high activities rivaling their early metal counterparts, but more importantly they offer unique properties for polymer architectural control and copolymerization with polar olefins. In this book, the most recent major breakthroughs in the development of new olefin polymerization catalysts, including early metal metallocene and non-metallocene complexes and late transition metal complexes, are discussed by leading experts. The authors highlight the most important discoveries in catalysts and their applications in designing new polyolefin-based functional materials.
Book Synopsis Artificial Metalloenzymes and MetalloDNAzymes in Catalysis by : Montserrat Diéguez
Download or read book Artificial Metalloenzymes and MetalloDNAzymes in Catalysis written by Montserrat Diéguez and published by John Wiley & Sons. This book was released on 2018-02-21 with total page 1200 pages. Available in PDF, EPUB and Kindle. Book excerpt: An important reference for researchers in the field of metal-enzyme hybrid catalysis Artificial Metalloenzymes and MetalloDNAzymes in Catalysis offers a comprehensive review of the most current strategies, developed over recent decades, for the design, synthesis, and optimization of these hybrid catalysts as well as material about their application. The contributors—noted experts in the field—present information on the preparation, characterization, and optimization of artificial metalloenzymes in a timely and authoritative manner. The authors present a thorough examination of this interesting new platform for catalysis that combines the excellent selective recognition/binding properties of enzymes with transition metal catalysts. The text includes information on the various applications of metal-enzyme hybrid catalysts for novel reactions, offers insights into the latest advances in the field, and contains an informative perspective on the future: Explores the development of artificial metalloenzymes, the modern and strongly evolving research field on the verge of industrial application Contains a comprehensive reference to the research area of metal-enzyme hybrid catalysis that has experienced tremendous growth in recent years Includes contributions from leading researchers in the field Shows how this new catalysis combines the selective recognition/binding properties of enzymes with transition metal catalysts Written for catalytic chemists, bioinorganic chemists, biochemists, and organic chemists, Artificial Metalloenzymes and MetalloDNAzymes in Catalysis offers a unique reference to the fundamentals, concepts, applications, and the most recent developments for more efficient and sustainable synthesis.
Book Synopsis Methodologies in Amine Synthesis by : Alfredo Ricci
Download or read book Methodologies in Amine Synthesis written by Alfredo Ricci and published by John Wiley & Sons. This book was released on 2021-04-26 with total page 480 pages. Available in PDF, EPUB and Kindle. Book excerpt: Discover a comprehensive overview of efficient synthetic routes to an important compound class in organic and pharmaceutical chemistry Methodologies in Amine Synthesis: Challenges and Applications delivers powerful and state-of-the-art methods for the efficient preparation of amines. The text summarizes recent advances in the electrophilic amination reaction, hydroamination, C-H amination and newly developed photocatalytic approaches. The distinguished editor has included resources that discuss organocatalytic and enzymatic routes to the generation of amines under mild and environmentally friendly conditions. The book also highlights the relevance of the amino function in bioactive molecules, drugs, and smart materials, as well as the palladium-catalyzed aromatic amination reaction. It presents efficient and practical synthetic methods, highlights the opportunities and challenges associated with each, and discusses their possible applications in pharmaceutical chemistry and materials science. Edited by the expert who wrote Modern Amination Methods and Amino Group Chemistry, the book includes a breadth and depth of material essential to the practice of academic and industrial chemists working in organic synthesis and catalysis. Readers will also benefit from the inclusion of: A thorough introduction to new openings and perspectives in the electrophilic amination Discussions of asymmetric catalysed hydroaminomethylation and amino organocatalysis A treatment of the synthetic application of transaminase or MAO biocatalysis to the synthesis of amines An exploration of recent developments in C-H amination, as well as photocatalytic approaches to the synthesis of amines An examination of primary amines from renewable bio-based resources Perfect for organic, natural product, catalytic, medicinal, and polymer chemists, Methodologies in Amine Synthesis: Challenges and Applications will also earn a place in the libraries of materials scientists and chemists working with organometallics who desire a one-stop reference edited by a well-known expert in the field.
Book Synopsis Asymmetric Synthesis and Mechanistic Insights of Transition-Metal-Catalyzed Hydrogenation by : Jianping Yang
Download or read book Asymmetric Synthesis and Mechanistic Insights of Transition-Metal-Catalyzed Hydrogenation written by Jianping Yang and published by . This book was released on 2022 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Synthesis of Transition Metal N-heterocyclic Carbene Complexes and Applications in Catalysis by : Michael Holtz-Mulholland
Download or read book Synthesis of Transition Metal N-heterocyclic Carbene Complexes and Applications in Catalysis written by Michael Holtz-Mulholland and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Transition Metal Catalyzed Enantioselective Hydroboration and Hydrovinylation of Alkenes by : Krishnaja Duvvuri
Download or read book Transition Metal Catalyzed Enantioselective Hydroboration and Hydrovinylation of Alkenes written by Krishnaja Duvvuri and published by . This book was released on 2018 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt: Economic methods to stitch feedstocks onto molecules using chemical synthesis can greatly impact the design and manufacture of molecules, from medicine to materials. For example, olefins, one of the most abundantly obtained class of feedstocks from the petroleum refining industry, are starting carbon units for many of the processes used to produce value-added chemicals in the pharmaceutical, agrochemical and polymer industry. However, many of these processes are often limited with harsh reaction conditions, poor yields and low selectivities. Organic chemists have long been trying to address the unmet challenges in this field; to simultaneously activate and functionalize olefins under mild reaction conditions, with the desired level of precision and selectivity, bond-by-bond, in order to access high value-added molecules from cheap and abundant lower alkenes. My graduate research work focusses on developing methods to address the challenges in olefin activation by employing transition metal catalysts as powerful tools. Mimicking nature’s enzymes and its extra-ordinary selectivity, we seek to address olefin functionalization, more specifically carbon-boron and carbon-carbon bond forming reactions, which could provide a powerful means to access a broad range of advanced, highly functionalized target molecules of interest to medicinal chemistry and related areas. We seek to develop a highly efficient catalytic protocol using the earth abundant metal, cobalt, linked to suitable ligands, to achieve the hydroboration of unactivated olefins to obtain organo-borane products with desired level of yield and selectivity. Although these are highly versatile compounds having wide synthetic utility as pharmaceutical intermediates, there is a paucity of methods to make organo-boranes directly from feedstocks. In this research methodology, a systematic investigation of diverse classes of ligand-cobalt complexes was performed to activate unactivated olefins. Based on mechanistic insights and experimental observations, the ligands were optimized to get the best selectivity of the desired value-added products from substituted dienes. The parameters effecting yields such as organic solvents, temperature and catalyst loading were also examined to process the best yields. The operationally simple, yet unprecedented reactions we discovered expand the realm of hydrofunctionalizations to provide direct access to a number of boranes, of interest in organic synthesis. The resulting boron compounds were further transformed into several chiral building blocks, thus expanding the scope of the primary process for advanced synthesis. -aryl--aminobutyric acid (GABA) derivatives are a large class of medicinally active compounds, examples of which include (R)-Baclophen and (R)-Rolipram. Methods for the efficient enantioselective synthesis this class of compounds were explored through the asymmetric hydrovinylation reaction, the addition of ethylene to olefins. By employing finely tuned chiral nickel complexes, several -substituted styrenes of relevance were found to undergo hydrovinylation in good to modest enantioselectivites. Model subtstrates were further transformed into the GABA precursor illustrating that this class of medicinally active compounds can be accessed from simple starting materials using the hydrovinylation reaction. We expect that the discoveries like this will shorten the considerable distance between the conceptualization of a molecule as a drug candidate and its large-scale synthesis. Beyond this transformation we anticipate that this reactivity will inspire further advances in olefin functionalization.
Book Synopsis Organic Synthesis by : Belakatte Parameshwarappa Nandeshwarappa
Download or read book Organic Synthesis written by Belakatte Parameshwarappa Nandeshwarappa and published by BoD – Books on Demand. This book was released on 2020-05-27 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book ‘Organic Synthesis - A Nascent Relook’ is a compendium of the recent progress in all aspects of organic chemistry including bioorganic chemistry, organo-metallic chemistry, asymmetric synthesis, heterocyclic chemistry, natural product chemistry, catalytic, green chemistry and medicinal chemistry, polymer chemistry, as well as analytical methods in organic chemistry. The book presents the latest developments in these fields. The chapters are written by chosen experts who are internationally known for their eminent research contributions. Organic synthesis is the complete chemical synthesis of a target molecule. In this book, special emphasis is given to the synthesis of various bioactive heterocycles. Careful selection of various topics in this book will serve the rightful purpose for the chemistry community and the industrial houses at all levels.
Book Synopsis Applications of Amido-N-heterocyclic Carbene Ligands in Bifunctional Catalysis by : Christopher G. Daly
Download or read book Applications of Amido-N-heterocyclic Carbene Ligands in Bifunctional Catalysis written by Christopher G. Daly and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Transition Metal Catalyzed Hydroarylation of Multiple Bonds by :
Download or read book Transition Metal Catalyzed Hydroarylation of Multiple Bonds written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Catalysts provide foundational technology for the development of new materials and can enhance the efficiency of routes to known materials. New catalyst technologies offer the possibility of reducing energy and raw material consumption as well as enabling chemical processes with a lower environmental impact. The rising demand and expense of fossil resources has strained national and global economies and has increased the importance of accessing more efficient catalytic processes for the conversion of hydrocarbons to useful products. The goals of the research are to develop and understand single-site homogeneous catalysts for the conversion of readily available hydrocarbons into useful materials. A detailed understanding of these catalytic reactions could lead to the development of catalysts with improved activity, longevity and selectivity. Such transformations could reduce the environmental impact of hydrocarbon functionalization, conserve energy and valuable fossil resources and provide new technologies for the production of liquid fuels. This project is a collaborative effort that incorporates both experimental and computational studies to understand the details of transition metal catalyzed C-H activation and C-C bond forming reactions with olefins. Accomplishments of the current funding period include: (1) We have completed and published studies of C-H activation and catalytic olefin hydroarylation by TpRu[P(pyr)3](NCMe)R (pyr = N-pyrrolyl) complexes. While these systems efficiently initiate stoichiometric benzene C-H activation, catalytic olefin hydroarylation is hindered by inhibition of olefin coordination, which is a result of the steric bulk of the P(pyr)3 ligand. (2) We have extended our studies of catalytic olefin hydroarylation by TpRu(L)(NCMe)Ph systems to L = P(OCH2)3CEt. Thus, we have now completed detailed mechanistic studies of four systems with L = CO, PMe3, P(pyr)3 and P(OCH2)3CEt, which has provided a comprehensive understanding of the impact of steric and electronic parameters of 'L' on the catalytic hydroarylation of olefins. (3) We have completed and published a detailed mechanistic study of stoichiometric aromatic C-H activation by TpRu(L)(NCMe)Ph (L = CO or PMe3). These efforts have probed the impact of functionality para to the site of C-H activation for benzene substrates and have allowed us to develop a detailed model of the transition state for the C-H activation process. These results have led us to conclude that the C-H bond cleavage occurs by a [sigma]-bond metathesis process in which the C-H transfer is best viewed as an intramolecular proton transfer. (4) We have completed studies of Ru complexes possessing the N-heterocyclic carbene IMes (IMes = 1,3-bis-(2,4,6-trimethylphenyl)imidazol-2-ylidene). One of these systems is a unique four-coordinate Ru(II) complex that catalyzes the oxidative hydrophenylation of ethylene (in low yields) to produce styrene and ethane (utilizing ethylene as the hydrogen acceptor) as well as the hydrogenation of olefins, aldehydes and ketones. These results provide a map for the preparation of catalysts that are selective for oxidative olefin hydroarylation. (5) The ability of TpRu(PMe3)(NCMe)R systems to activate sp3 C-H bonds has been demonstrated including extension to subsequent C-C bond forming steps. These results open the door to the development of catalysts for the functionalization of more inert C-H bonds. (6) We have discovered that Pt(II) complexes supported by simple nitrogen-based ligands serve as catalysts for the hydroarylation of olefins. Given the extensive studies of Pt-based catalytic C-H activation, we believe these results will provide an entry point into an array of possible catalysts for hydrocarbon functionalization.
Book Synopsis Novel Olefin Metathesis Catalysts Bearing a Hemi-labile NHC Ligand by : Nicolas Cena
Download or read book Novel Olefin Metathesis Catalysts Bearing a Hemi-labile NHC Ligand written by Nicolas Cena and published by . This book was released on 2019 with total page 79 pages. Available in PDF, EPUB and Kindle. Book excerpt: The field of olefin metathesis has grown appreciatively in recent decades. Elucidation of the mechanism and a deeper understanding of the key intermediates have enabled chemists to design catalysts, which exhibit greater activity, stability, and selectivity towards a variety of substrates. However, the economic impact of performing this reaction on the industrial scale is often governed by the high cost of the catalysts in comparison to modest turnover numbers (TON). The lifetime of an active catalyst species depends on the stability of intermediates in the catalytic cycle, and this ultimately determines the TON. One of the remaining goals in the field is to further stabilize the intermediates of the catalytic cycle in order to prolong the catalyst lifetimes and increase turnover numbers (TON). The ruthenium catalytic species cycle through several electron deficient intermediates, which lead towards decomposition pathways. These decomposition pathways are directed towards reactions that provide the metal with additional electron density. The primary focus of this thesis project was to develop a new generation of olefin metathesis catalysts employing a tridentate N-heterocyclic carbene (NHC) ligand bearing a hemi labile pyridine arm in the ortho position of the aromatic ring. The rationale behind incorporating these functional groups was to stabilize the reactive intermediates of the catalytic cycle via electron donation from the ether O → Ru and the pyridine N → Ru. These ligands increase the likelihood of stabilization of the metal center by chelation of electron-donating substituents from the O and N, thus adding electron density back into the electron-deficient metal center. The ligand not only donates electron density back to the metal but also shields the sterically open position trans to the NHC. The hypothesis was that stabilizing these reactive intermediates would prolong the lifetime of the active catalyst and thus increase TON and allow for a much lower catalyst loading for industrial applications, thus vastly impacting the economical aspect of olefin metathesis processes. A novel set of two catalysts bearing tridentate NHC ligands with hemi labile pyridine arms were synthesized. The ligands differed in one aromatic ring containing either a 2,6 diisopropyl phenyl (DIPP) or mesityl (Mes) moiety. The result of the x-ray crystallographic analysis revealed the NHC ligand coordinated in the proposed tridentate meridional fashion around the central Ru atom. This coordination was proposed in order to affect a hinge-like mechanism in which the pyridine arm's hemi-labile nature would be in close proximity to the electron deficient metal center, so that it could bind reversibly in order to satiate the metal's desire for electron density while still allowing reactivity upon dissociation. NMR spectroscopy revealed information about the proposed structure in solution and revealed that the ligand was bound in solution to the metal center in one orientation, owing to the coordination of the O and N to the metal center. Catalyst decomposition studies were performed using the methylidene variant of the catalysts at elevated temperatures under inert conditions as well as under an atmosphere of ethylene gas. The purpose of intentionally decomposing the catalyst was to generate the electron deficient Ru center and probe the stabilizing effects of the pyridine arm coordination. These reactive intermediates are electronically and sterically more similar to the 14-electron active catalyst than the 16-electron pre-catalyst, giving insight into how the catalysts behave in solution upon metathesis active conditions. Decomposition products of the DIPP variant were analyzed by NMR and x-ray crystallography, giving insight into possible decomposition pathways for these novel catalysts. The catalysts were screened for metathesis activity in ring-closing metathesis (RCM) and ring opening metathesis polymerization (ROMP). Both showed noticeable differences from previous generations of Grubbs and Hoveyda-Grubbs catalysts in overall efficacy. The prolonged lifetimes of these new catalysts were competitive with commercially available catalysts in terms of lifetime and TON. Though slightly lower in TON, these catalysts lasted much longer in solution at elevated temperatures than their predecessors, thus indicating much more stabilized reactive intermediates. The data gathered from decomposition studies and metathesis activity along with NMR and x-ray crystallography allowed for potential structure-activity relationships and mechanistic pathways to be proposed. The insight into olefin metathesis catalyst structure, performance, and design provided by these studies may assist in future endeavors in the field of olefin metathesis catalyst design and employment.
