Download or read book Synthesis and Characterization of Homometallic heterometallic Palladium Carbonyl Phosphine Clusters Generated Via Reactions of a High nuclearity Palladium nickel Cluster Precursor with Trialkylphosphines written by Jatuporn Wittayakun and published by . This book was released on 2000 with total page 287 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2000 with total page 782 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book New High nuclearity Homometallic heterometallic Palladium and Gold nickle Carbonyl Clusters written by Nguyet Thi Tran and published by . This book was released on 1998 with total page 680 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book New CO PR3 ligated Homo palladium and Heterometallic Nickel palladium Nanoclusters written by and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reactions of the nanosized homopalladium precursor Pd10(CO)12(PR3)6 (R = Et, i-Pr) with the dianionic [Ni6(CO)12]2- ([NMe4]+ salt) have produced important homopalladium and heterometallic nickel-palladium nanosized clusters. A "structure-to-synthesis" approach is utilized to possibly design alternative synthetic pathways and optimize yields following structural determinations. The synthesis of three new X-ray crystallographically-determined structures and the related structural redetermination of the multishell Pd145 cluster (which revealed 12 additional CO ligands) are reported herein. The synthesis of the Pd10 precursor with bulky triisopropylphosphine ligands was primarily carried out with the goal of stabilizing a two-shell Pd55 cluster and thereby sterically preventing its further conversion into the known Pd145 cluster. The successful formation, structural characterization, and spectroscopic characterization of this 55-atom two shell product, the new icosahedral Pd55(Îo3-CO)20{P(i-Pr)3}12 cluster, is reported in the second chapter. This nanosized two-shell 55 metal-atom cluster is the first crystallographically proven example of a relatively stable 55 metal-atom icosahedral cluster and can be seen as a new intermediate in a series of pseudo-icosahedral multishell clusters inclulding the 145 palladium-atom cluster. In the third chapter, the preparation of various crystal salts of the [Pd12+xNi8-x(Îơ4-O)(CO)22(PEt3)4]2- dianion (x = 0.54, 0.60) containing an unprecedented [PdxNi4-x(Îơ4-O)] fragment is given; X-ray crystallographic and spectroscopic (31P{1H}NMR, FTIR) characterization of this dianion are reported along with a comparative analysis of its structure and that of the closely related structure without the tetracoordinated oxo atom. A new synthetic pathway and structural determination of the three-shell icosahedral Pd145(CO)72(PEt3)30 is presented in the fourth chapter, wherein the establishment of its carbonyl composition is unambiguously determined crystallographically. The fifth chapter details the synthesis and structural determination of the nanosized homopalladium cluster Pd48(CO)32{P(i-Pr)3}12.
Download or read book Development of New Classes of Palladium and Nickel Catalyzed Carbonylation Reactions written by Jevgenijs Tjutrins and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "This thesis describes the development of new palladium and nickel catalyzed carbonylation reactions to efficiently and rapidly generate products with minimal waste. These reactions can be carried out using commercially and/or readily available starting materials, including imines, acid chlorides, aryl iodides, alkynes, alkenes and carbon monoxide. In chapter 2, we describe a palladium catalyzed carbonylative synthesis of polysubstituted imidazoles. This transformation involves a tandem catalytic process, where a single palladium catalyst mediates both the carbonylation of aryl halides to form acid chlorides, as well as cyclocarbonylation of a-chloroamides, to generate 1,3-dipoles. Finally, a regioselective 1,3-dipolar cycloaddition with electron poor imines furnishes tetra-substituted imidazoles. Overall this provides a route to prepare imidazoles from five readily available building blocks: two electronically distinct imines, aryl halides and two molecules of CO. In chapter 3, we describe a nickel catalyzed approach to synthesize of isoindolinones via the carbonylation of aryl iodides in the presence of imines. In this, the nickel catalyzed in situ generation of acid chlorides via aryl halide carbonylation allows the formation of a chloroamides, which in turn undergo an intramolecular cyclization to form isoindolinones. This reaction offers an efficient alternative to traditional syntheses of isoindolinones, which often require the initial assembly of the appropriate aryl-tethered precursors for cyclization. In chapter 4, we describe the development of a palladium catalyzed, electrophilic approach to the carbonylative C-H bond functionalization of a range of heterocycles. Mechanistic studies show that the Pd/PtBu3 catalyst can mediate the in situ formation of highly electrophilic aroyl iodide intermediates, which react with heterocycles forming aryl-(hetero)aryl ketones. This provides a general methodology to construct ketones from aryl iodides and electron rich heterocycles without the need to prefunctionalize the heterocycle, install directing groups, or exploit high energy starting materials (e.g. acid chlorides). Chapter 5 describes mechanistic studies on the palladium catalyzed multicomponent synthesis of 1,3-oxazolium-5-olates (Münchnones). Previous work in our laboratory has shown that Münchnones can be generated via the palladium catalyzed multicomponent coupling of acid chlorides, imines and CO. In order to better understand this reaction, we synthesized and characterized key reactive intermediates, studied stoichiometric model reactions, and performed kinetic studies on catalytic reaction. These allowed the elucidation of the role of the catalyst structure, rate determining steps, as well as the importance of off cycle steps in this transformation. In chapter 6, we show how the mechanistic insights laid out in the previous chapter can be applied to create a highly active catalytic system for synthesis of 1,3-oxazolium-5-olates. By employing a sterically encumbered pyrrole-based phosphine ligand, which can be more easily displaced by carbon monoxide for carbonylation, we have created a catalyst that is more than ten times more active that previous systems for this reaction. When coupled with alkyne cycloaddition, this offers a broadly generalizable route to form polysubstituted pyrroles from simple imines, acid chlorides and alkynes. This approach has been applied to the multicomponent synthesis of Atorvastatin (i.e., Lipitor). " --
Download or read book Palladium Assisted Synthesis of Heterocycles written by Navjeet Kaur and published by CRC Press. This book was released on 2019-05-01 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a compilation of the recent applications of palladium catalysts in organic synthesis. The book demonstrates that it is a highly dynamic research field. This methodology has emerged as a powerful tool for the efficient and chemoselective synthesis of heterocyclic molecules. In the past few years, several strategies have been pointed out to pursue more efficient, sustainable, and environment friendly chemical processes. Among those strategies, catalysis and the design of new processes that avoid the use of toxic reagents have been the focus of intense research.
Download or read book Palladium Reagents and Catalysts written by Jiro Tsuji and published by . This book was released on 1995 with total page 596 pages. Available in PDF, EPUB and Kindle. Book excerpt: Basic chemistry of organopalladium compounds; Classification of the reactions involving Pd(II) compounds and Pd(O) complexes.
Download or read book Synthesis and Reactivity of Nickel Palladium and Platinum Phosphine Complexes with Hydridoamido Hydridophenoxo and Dithiooxalato Ligands written by Robert L. Cowan and published by . This book was released on 1989 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Palladium in Organic Synthesis written by Jiro Tsuji and published by Springer. This book was released on 2010-11-23 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Palladium is a remarkable metal. In particular, organopalladium chemistry has made remarkable progress over the last 30 years. That progress is still continuing, without any end in sight. This book presents a number of accounts and reviews on the novel Pd-catalyzed reactions discovered mainly in the last five years. The book covers Pd-catalyzed reactions that are new – entirely different from the more standard ones. Topics such as new reactions involving ß-carbon elimination and formation of palladacycles as key reactions, cross-coupling of unactivated alkyl electrophiles with organometallic compounds, arylation via C-H bond cleavage, Pd/norbornene-catalyzed aromatic functionalizations, three-component cyclizations of allenes, use of N-heterocyclic carbenes as ligands, asymmetric reactions catalyzed by Pd(II) compounds such as Lewis acids, cycloadditions of arynes and alkynes, and nucleophilic attack by Pd species are surveyed in detail by researchers who have made important contributions to these fields. The book addresses graduate students majoring in organic synthesis and researchers in academic and industrial institutes.
Download or read book Palladium and Nickel Catalyzed Transformations Forming Functionalized Dihydroisoquinolinones Chromans Dihydrobenzofurans and Oxindoles written by Hyung Yoon and published by Springer. This book was released on 2020-10-19 with total page 237 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents Pd- and Ni-catalyzed transformations generating functionalized heterocycles. Transition metal catalysis is at the forefront of synthetic organic chemistry since it offers new and powerful methods to forge carbon–carbon bonds in high atom- and step-economy. In Chapter 1, the author describes a Pd- and Ni-catalyzed cycloisomerization of aryl iodides to alkyl iodides, known as carboiodination. In the context of the Pd-catalyzed variant, the chapter explores the production of enantioenriched carboxamides through diastereoselective Pd-catalyzed carboiodination. It then discusses Ni-catalyzed reactions to generate oxindoles and an enantioselective variant employing a dual ligand system. Chapter 2 introduces readers to a Pd-catalyzed diastereoselective anion-capture cascade. It also examines diastereoselective Pd-catalyzed aryl cyanation to synthesize alkyl nitriles, a method that generates high yields of borylated chromans as a single diastereomer, and highlights its synthetic utility. Lastly, Chapter 3 presents a Pd-catalyzed domino process harnessing carbopalladation, C–H activation and π-system insertion (benzynes and alkynes) to generate spirocycles. It also describes the mechanistic studies performed on these reactions.
Download or read book Palladium catalyzed Carbonylative Synthesis of Acid Chorides and Use in Multicomponent Coupling Reactions written by Jeffrey Quesnel and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "The palladium-catalyzed carbonylation of aryl halides has proven to be a powerful method for the synthesis of carbonyl-containing compounds. This thesis describes a unique way of performing palladium-catalyzed carbonylations: through the generation of acid chlorides as products and as reactive intermediates.Chapter 2 describes the application of palladium-catalyzed aryl iodide carbonylation to the five-component synthesis of imidazolinium carboxylates. This reaction involves the coupling of the palladium-catalyzed carbonylation of aryl halides with the cyclocarbonylation of [alpha]-chloroamides, and provides an efficient route to generate imidazolinium salts from aryl iodides, imines, and carbon monoxide. A variety of imidazolinium products can be synthesized, including those whose derivatives are relevant to pharmacologically active compounds. Subsequent deprotection and aromitization can then lead to triaryl-substituted imidazoles.In Chapter 3, we report a new approach to acid chloride synthesis via the palladium-catalyzed carbonylation of aryl iodides. The combination of sterically encumbered phosphines (PtBu3) and CO coordination has been found to facilitate the rapid carbonylation of aryl iodides into acid chlorides via reductive elimination from (tBu3P)(CO)Pd(COAr)Cl. The formation of acid chlorides can also be exploited to perform traditional aminocarbonylation reactions under exceptionally mild conditions (ambient temperature and pressure), and with a range of weakly nucleophilic substrates.Chapter 4 describes the adaptation of this acid chloride synthesis to include less reactive aryl bromide coupling partners. Interestingly, the same PtBu3 ligand found to be most efficient for acid chloride synthesis from aryl iodides also proved best for aryl bromide chlorocarbonylation, suggesting the unusual ability of this ligand to efficiently mediate both oxidative addition and reductive elimination reactions. Mechanistic studies show that the palladium coordination environment is an important aspect of the key C-Cl reductive elimination step. In contrast to smaller phosphine ligands, the bulky PtBu3 leads to the in situ formation of a three coordinate (tBu3P)(CO)Pd(COAr)Cl complexes, which can readily coordinate CO to facilitate reductive elimination. Trapping of in situ generated acid chlorides with simple hydrazine allows, for the first time, the efficient synthesis of unsubstituted aroyl hydrazides via a palladium-catalyzed carbonylation reaction.In Chapter 5, we describe density functional theory (DFT) study of the mechanism for the palladium/PtBu3 catalyzed chlorocarbonylation of aryl iodides into acid chlorides. The results demonstrate a synergistic effect of CO and phosphine ligands on oxidative addition and reductive elimination chemistry of aryl/aroyl halides, consistent with what has been noted in experiments. The reductive elimination of PhCOCl from the four-coordinate PhCOPd(PtBu3)Cl(CO) complex is found to proceed via a surprisingly low energy pathway, and is facilitated by the coordination of CO to the three-coordinate PhCOPd(PtBu3)Cl. Examination of a series of PhCOPd(PR3)Cl(CO) complexes (R = Me, Et, iPr, tBu) shows that while most phosphines generate relatively stable four-coordinate complexes, the tertiary steric bulk of PtBu3 destabilizes this complex by steric clashing with the cis-CO ligand. This significantly lowers the barrier to acid choride reductive elimination, and makes this step thermodynamically favourable.Chapter 6 presents an alternative to the catalytic acid chloride chemistry discussed in Chapters 3 and 4, where instead 4-dimethylaminopyridine (DMAP) is shown to couple with aryl halides and carbon monoxide to form isolable and highly electrophilic aroyl-DMAP salts. The reaction is easily scalable to prepare multigram quantities of product with low catalyst loadings, while the precipitation of these salts as they form leads to products with low impurities. " --
Download or read book The Synthesis and Characterization of Large Metal Clusters Containing Gold And or Palladium written by Lissa Taka Jennings Nelson and published by . This book was released on 1992 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Design and Synthesis of Phosphine Ligands for Palladium catalyzed Coupling Reactions written by William Scott Brown and published by . This book was released on 2009 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt: The synthesis and design of new phosphines is a continuing area of interest. In designing new phosphines there are a number of design features that need be considered. For palladium catalyzed coupling reactions, sterically demanding and electron releasing ligands are generally most effective in promoting the reaction. In evaluating the hydrophobic phosphines utilized in the Suzuki coupling, the neopentyl derivatives of TTBP (tri-tert-butylphosphine) were investigated. The effect of the addition of a neopentyl group increases the cone angle and impacts the electron donation by decreasing it relative to TTBP. The application in Suzuki coupling shows that a palladium catalyst with a neopentyl phosphine ligand demonstrates good to excellent yields with aryl bromides at room temperature. In the design of new phosphines, building in polar groups generates the ability to take advantage of using water as a solvent or co-solvent. The synthesis of the water soluble ligands DTBPPS (di-tert-butylphosphoniumpropane sulfonate) and DAPPS (di-adamantylphosphoniumpropane sulfonate) led to their testing in Sonogashira and Suzuki coupling reactions. Both ligands give catalysts that show good to excellent conversion of aryl bromides to products at room temperature. For aryl chlorides elevated temperatures are required. In expanding the water-soluble ligands into other palladium coupling reactions, DAPPS was developed in the carbonylation of aryl bromides. The palladium/DAPPS-catalyzed carbonylation coupling reactions show good to excellent conversion of aryl bromides to carbonylated products. This is the first example of a water-soluble alkylphosphine promoting carbonylation of an aryl bromide.
Download or read book High valent Organometallic Palladium and Nickel Complexes and Their Roles in Carbon carbon and Carbon heteroatom Bond Formation Reactions written by Jason W. Schultz and published by . This book was released on 2016 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis Characterization and Reactivity of Mononuclear Palladium Complexes Bearing Nitrogen and Carbon donor Ligands written by Nicholas Ruhs and published by . This book was released on 2017 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt: The importance of Pd-catalyzed C--H functionalization reactions for chemical transformations has been widely studied over the last several decades. Much of the research to date has focused on conventional Pd0/II catalytic cycles. However, more recent studies have shown that many transformations can also follow a PdII/IV catalytic cycle. High-valent PdIII and PdIV species are often proposed to be important intermediates in such transformations. C--H coupling reactions involving high-valent intermediates often involve the oxidation of a PdII species to a PdIII or PdIV complex, which can then undergo subsequent C--heteroatom bond formation. However, the need for harsh oxidants and reaction conditions in many of these reactions hinders their practical applicability. The focus of this work is to study the properties and reactivity of PdII, PdIII, and PdIV complexes through modifications of the supporting macrocyclic ligands. Another goal of this work is to probe the ability of these complexes to facilitate C--H activation and C--heteroatom bond formation reactions using environmentally benign oxidants.Our lab reported the synthesis and characterization of the first organometallic mononuclear PdIII complexes stabilized by the tetradentate ligand N,N'-di-tert-butyl-2,11-diaza[3,3](2,6)pyridinophane (tBuN4). In order to further probe the Pd chemistry with this class of ligands, we prepared ligands with modifications to the steric bulk on the amine groups. In the first study detailed in chapter 2, the synthesis and characterization of PdII and PdIII complexes supported by N,N'-di-neo-pentyl-2,11-diaza[3,3](2,6)-pyridinophane(NpN4) and N,N'-di-benzyl-2,11-diaza[3,3](2,6)-pyridinophane(BzN4) is reported. Interestingly, the spectroscopic and crystallographic property of the newly synthesized complexes falls between the tBuN4 and MeN4 complexes. The C--C and C--heteroatom bond formation reactivity of the NpN4 and BzN4 supported complexes is also similar to our group's previously reported complexes.We also prepared and studied a series of Pd complexes bearing a modified tetradentate pyridinophane ligand, tBuN3CH. Essentially, we have replaced one of the nitrogen donor atoms from the N4 ligand with a carbon atom and have also introduced a new C--H bond. Due to its expected positioning near the metal center, this bond has the potential to undergo intramolecular C--H bond activation. In order to study the reactivity of this ligand, electronic modifications were made by substituting various electron-donating and withdrawing groups in the para position to this new C--H bond. In chapter 3, the synthesis and characterization of a series of PdII, PdIII, and PdIV complexes stabilized by the N3CH ligand is reported. Interestingly, a spectroscopic and crystallographic study of the pRN3CHPdII(OAc)2 complexes reveals that the Cipso--H bond remains unactivated at the PdII stage. However, upon oxidation to PdIII, the Cipso--H bond is activated.Interestingly, we discovered that the aerobic oxidation of the PdII complex [pRN3CHPdII(MeCN)](BF4) leads to the formation of the PdIII complex [pRN3CHPdIII(MeCN)](ClO4)2 at room temperature. Surprisingly, the C--H activation reaction proceeds in the presence of oxygen without the need for external base. Furthermore, the moderate rate of the reaction allowed us to investigate the mechanism of the reaction by utilizing kinetics and UV-Vis spectroscopy. Detailed mechanistic studies revealed that C--H activation of the Cipso--H bond is the rate determining step of the reaction.
Download or read book Silicon Containing Dendritic Polymers written by Petar R. Dvornic and published by Springer Science & Business Media. This book was released on 2009-01-09 with total page 428 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the last two decades silicon-containing dendritic polymers have become one of the fastest growing areas of development in polymer science. The eruption of interest in these new polymers stems from their unprecedented molecular architecture, unique resulting properties and the realization that they represent ideal building blocks for chemical nanotechnology. This is the first book to solely focus on silicon-containing dendritic polymers. The contributions of those experts who originally introduced each field or played a major role in its progress are reported. The developments in all major areas of this field are presented from their origins to the present. It is anticipated that this text will become an invaluable guide and vanguard of reference for experienced scientists interested in the fields of polymer and material science, synthetic chemistry, and nanotechnology. It will also serve advanced graduate students either as a source of creative inspiration or as a textbook for appropriate courses.
Download or read book Carbon Ligands written by Yves Canac and published by Mdpi AG. This book was released on 2021-06-30 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: Homogeneous catalysis owes its success, in large part, to the development of a wide range of ligands with well-defined electronic and steric properties, which have thus made it possible to adjust the behavior of many organometallic complexes. However, ligands used in catalysis have long been centered on elements of group 15, and it is only more recently that carbon ligands have proved to be valuable alternatives with the emergence of cyclic diaminocarbenes (NHC).This Special Issue aims to provide a contemporary overview of the advances in carbon ligand chemistry from fundamental aspects to applications.
