Download or read book Synthesis Dioxygen Reactivity and Electrochemistry of Novel Mononuclear and Heterobinuclear Cobalt Complexes written by Stephen Fox and published by . This book was released on 1984 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Synthesis Electrochemistry and Homogeneous Electron Transfer Reactivity of Cobalt III Pentaalkylamine Complexes and Their Use as Model Reactants for Nonadiabatic Electron Transfer Reactions written by Michael Edward Ketterer and published by . This book was released on 1985 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Chemistry Electrochemistry and Electron Transfer Induced Reactions of Cobalt Complexes with Fluorinated Ligands written by Kihanduwage N. Gunawardhana and published by . This book was released on 2007 with total page 213 pages. Available in PDF, EPUB and Kindle. Book excerpt: The chemical or electrochemical reduction of the trifluoroacetyl complex CF3COCo(CO)3PPh3 involves a single electron transfer yielding trifluoromethyl radical and an anionic cobalt carbonyl complex. The mechanism is proposed to involve electron transfer followed by initial dissociation of either a carbonyl or phosphine ligand from the 19-electron [CF3COCo(CO)3PPh3]- anion. The resulting 17-electron intermediate undergoes subsequent one-electron reductive elimination of trifluoromethyl radical by homolytic cleavage of the carbon-carbon bond of the trifluoroacetyl group. The CF3. radical can be trapped by either benzophenone anion, forming the anion of [alpha]-(trifluoromethyl)benzhydrol, or Bu3SnH, yielding CF3H. The final organometallic product is an 18-electron anion, either [Co(CO)4]- or [Co(CO)3(PPh3)]-, depending upon which ligand is initially lost. The chemical or electrochemical reduction CF3Co(CO)3PPh3 is a two-electron process involving heterolytic cobalt-carbon bond cleavage to yield trifluoromethyl anion and cobalt carbonyl anions. The trifluoromethyl anion rapidly decomposes to fluoride and difluorocarbene. This carbene may dimerize to form C2F4. The unstable fluoro carbene can also be trapped by cyclohexene. The mechanism proposed for the reduction of C6F5Co(CO)3PPh3 involves a homolytic cobalt-carbon bond cleavage to form C6F5. radical. The resultant C6F5. radical abstracts hydrogen or deuterium from the solvent or trace amounts of water to produce C6F5H or C6F5D. With an excess of reducing agent this C6F5. radical can be further reduced to C6F5- anion before forming pentafluorobenzene by protonation. The inorganic fragment, the 18-electron [Co(CO)3PPh3]- anion, may participate in a ligand exchange reaction to form [Co(CO)4]-. In addition, interesting reactivity was observed between C6F5Co(CO)3PPh3 and tin hydrides, deuterides and chlorides without any reducing agents. We have demonstrated that ligand replacement reactions can be used for the synthesis of new cobalt-NHC complexes with fluorinated alkyl, acyl and aryl ligands. In addition, the X-ray crystal structure of CF3COCo(CO)3PPh3 was obtained to compare the bond lengths and bond angles with other related compounds. An unusual Co-C(acyl) bond length was observed for CF3COCo(CO)3PPh3. Considering the bond lengths of other alkyl and acyl complexes, it can generally be argued that the position of the alkyl/acyl equilibrium varies with the Co-C(alkyl/acyl) bond length.
Download or read book Synthesis and Reactivity of Cobalt III Complexes written by Anthony N. Enweze and published by . This book was released on 1983 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis and Reactivity of Cobalt Zinc Copper and Iron Dimetallic Complexes Using Bis carboxylate and 1 8 napthyridine based Dinucleating Ligands written by Chuan He and published by . This book was released on 2000 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis and Reactivity of Low coordinate Cobalt Complexes and Iron I Alkyl Complexes Supported by beta diketiminate Ligand written by Keying Ding and published by . This book was released on 2009 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis and Reactions of Cobalt and Ruthenium Isonitrile Complexes written by Gerold J. Miller and published by . This book was released on 1989 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Oxidation State Roulette written by Brandon Fitchett and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The use of rare and expensive noble metals in the chemical industry as organometallic catalysts has grown exponentially in the past few decades due to their high activity, selectivity and their ability to catalyze a wide range of reactions. With this growth in use has also come a proportional growth in concern as these toxic metals inevitably leach into the environment and their negative effects on public health and our ecosystems are becoming better understood. First-row transition metal catalysts provide both environmental and economic benefits as alternatives to these noble metals due to their lower toxicity and cheaper costs. The two-electron chemistry that makes the noble metals so attractive however, is more challenging to accomplish with first-row transition metals. Intelligently designing the ligand scaffold which surrounds the metal can mitigate or even eliminate some of the shortfalls of these first-row metals. Some key features that should be considered when designing a ligand are: 1) a strong chelating ability so the ligand can stay attached to the metal, 2) incorporation of strong donors to favour low-spin complexes, 3) inclusion of hemilabile groups to allow for substrate activation and metal stabilization throughout various oxidation states, 4) redox activity to be able to donate or accept electrons, and 5) inclusion of Lewis base functionalities which are able to assist the substrate activation. Ligands which incorporate these features are known as bifunctional ligands as they can accomplish more than one function in the catalytic cycle. Developing first-row transition metal complexes containing these ligands may enable these species to replicate the reactivity and selectivity generally associated with the precious metals. Being able to replace the noble metals used in industry with these catalysts would have tremendous environmental and economic benefits. The objective of this thesis is to advance the field of bifunctional catalysis by examining the behaviour of two sterically svelte, tridentate SNS ligands containing hard nitrogen and soft sulphur donors when bonded to cobalt. Previous work with iron provides a template of the ligand behaviour to which cobalt can be compared, allowing us to contrast the effects exerted by the different metals. After an introduction to bifunctional catalysis in Chapter 1, Chapter 2 describes the reactivity of the amido ligand, SMeNHSMe, with precursors ranging from Co(I) to Co(III), all of which yielded the 19e- pseudooctahedral cobalt(II) bis-amido complex, Co(SMeN-SMe)2 characterized by 1H NMR spectroscopy, single-crystal X-ray crystallography and cyclic voltammetry. Although this complex has a similar structure as the Fe analogue, the cobalt bis-amido complex did not exhibit the same hemilabile behaviour that allowed for simple ligand substitution of one of the thioether groups. Instead it reacted reversibly with 2,2'-bipyridine while 1,2-bis(dimethylphosphino)ethane (DMPE) and 2,6-dimethylphenyl isocyanide both triggered additional redox chemistry accompanied by the loss of protonated SMeNHSMe. In contrast, protonation gave the cobalt(II) amido-amine cation, [Co(SMeNSMe)(SMeNHSMe)](NTf2), which allowed for substitution of the protonated ligand by acetonitrile, triphenylphosphine and 2,2'-bipyridine based on 1H NMR evidence. The ability of Co(SMeNSMe)2 to act as a precatalyst for ammonia-borane dehydrogenation was also probed, revealing that it was unstable under these conditions. Addition of one equivalent of DMPE per cobalt, however, resulted in better activity with a preference for linear aminoborane oligomers using ammonia-borane and, surprisingly, to a change in selectivity to prefer cyclic products when moving to methylamine-borane. Chapter 3 delves into the chemistry of the thiolate ligand, SMeNHS, which formed a new 18e- cobalt(III) pseudooctahedral complex, Co(S-NC-)(SMe)(DEPE), from oxidative addition of the Caryl-SMe bond. Scaling up this reaction resulted instead in formation of an imine-coupled [Co(N2S2)]- anion which was characterized by 1H NMR/EPR spectroscopy, single-crystal X-ray diffraction, cyclic voltammetry and DFT studies. The latter revealed an interesting electronic structure with two electrons delocalized in the ligand, demonstrating the non-innocent nature of the N2S2 ligand. While the analogous iron complex proved to be an effective pre-catalyst for the hydroboration of aldehydes with selectivity against ketones, this behaviour was not observed with [Co(N2S2)]- which gave a slower rate and less selectivity. The knowledge acquired from this thesis work has advanced the field of bifunctional catalysis by extending the application of these two SNS ligands from iron to cobalt, revealing unpredictable differences in reactivity between the metals. By comparing the behaviour of these ligands with iron and cobalt, we gain a better understanding of the chemistry that is accessible by these ligands and the applications for which they may be used. This increased knowledge contributes to our long-term goal of replacing expensive and toxic noble metals with more benign first-row transition metals, improving the sustainability of the chemical industry.
Download or read book Synthesis and Study of Coordination Compounds of Cobalt Copper Palladium and Nickel with Polydentate Ligands Containing Sulfur written by Tatiana Straistari and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work focuses on the synthesis, the characterization and the catalytic evaluation in the reduction of protons into dihydrogen, of new complexes of Ni(II), Co(III), Cu(II) and Pd(II) based ligands Type thiosemicarbazone. The catalytically active species during the process of the proton reduction was studied by cyclic voltammetry and mechanisms were formulated on the basis quantum chemical calculation.The first chapter introduces the scientific context, the goals and the main objectives of this work. The second chapter concerns the synthesis and the characterization of the N2S2 ligands and their associated mononuclear complexes, Ni, Cu and Pd. The third chapter presents the synthesis and the characterization of binuclear Co and trinuclear Ni based on N2S2 ligand.Electrochemical studies of these complexes in DMF in the presence of a proton source (trifluoroacetic acid), allowed us to evaluate their catalytic efficiency. Our results show that Cu and Pd complexes have a specific irreversible wave for the reduction of protons, but decomposition is observed during electrolysis, which makes these uninteresting complexes for the reduction of protons.On the contrary, Ni and Co complexes showed an electrochemical stability and good catalytic performances. In particular, the new mononuclear Ni complex exhibits remarkable catalytic properties that rank it among the best catalysts for the reduction of protons reported in the literature. All this work provided a complete description of the electrochemical behavior of N2S2 thiosemicarbazone ligands complexed to transition metals. It allows considering future developments in improving the catalytic properties of these complexes.
Download or read book Reactions of Some Mononuclear and Binuclear Cobalt III Complexes in Aqueous Solution written by Julian David Edwards and published by . This book was released on 1974 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book American Doctoral Dissertations written by and published by . This book was released on 1990 with total page 768 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Cage Metal Complexes written by Yan Voloshin and published by Springer. This book was released on 2017-05-11 with total page 475 pages. Available in PDF, EPUB and Kindle. Book excerpt: This fundamental book presents the most comprehensive summary of the current state in chemistry of cage metal complexes. After their previous book “The Encapsulation Phenomenon” (www.springer.com/978-3-319-27737-0) the authors in this book focus on the encapsulation of metal ions by different types of three-dimensional mono- and polynucleating caging ligands. Within these cage metal complexes, (metal) ions can be isolated from external factors. The book provides both a classification of the cage compounds and summaries of synthetic approaches. On that basis the authors then describe the unique chemical and physical properties and the resulting reactivity of the cage compounds, as well as practical and potential applications as potent topological drugs and prodrugs, antifibrillogenic agents, radiodiagnostic and radiotherapeutic compounds, paramagnetic probes, single-molecule magnets, electrocatalysts for hydrogen production, (photo)electronic devices, and many more. Readers will find a well-structured and concise overview, with particular emphasis on a review of synthesis and reactivity of various cage metal complexes, summarizing over 400 literature references, clearly presented in over 300 color schemes and figures.
Download or read book Progress in Inorganic Chemistry Volume 7 written by F. Albert Cotton and published by John Wiley & Sons. This book was released on 2009-09-17 with total page 482 pages. Available in PDF, EPUB and Kindle. Book excerpt: This comprehensive series of volumes on inorganic chemistry provides inorganic chemists with a forum for critical, authoritative evaluations of advances in every area of the discipline. Every volume reports recent progress with a significant, up-to-date selection of papers by internationally recognized researchers, complemented by detailed discussions and complete documentation. Each volume features a complete subject index and the series includes a cumulative index as well.
Download or read book Iron Porphyrins written by A. B. P. Lever and published by Wiley-VCH. This book was released on 1989-03-31 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt: Porphyrins play a vital role in many biological functions including oxygen transport, electron transfer and catalyzing the incorporation of oxygen into other molecules. This current survey discusses the use of modern physical techniques to probe porphyrin structure and function. The authors review the data available through a particular technique and show what can be learned therefrom about the (electronic) structure and function of biologically important porphyrins. The techniques include magnetic circular dichroism, X-ray absorption fine structure (EXAFS) and Mössbauer spectroscopies. All contributors are well known in their respective fields, enjoying world-wide reputation.
Download or read book Inorganic Reaction Mechanisms Part 1 Volume 13 written by John O. Edwards and published by John Wiley & Sons. This book was released on 2009-09-17 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt: This comprehensive series of volumes on inorganic chemistry provides inorganic chemists with a forum for critical, authoritative evaluations of advances in every area of the discipline. Every volume reports recent progress with a significant, up-to-date selection of papers by internationally recognized researchers, complemented by detailed discussions and complete documentation. Each volume features a complete subject index and the series includes a cumulative index as well.
Download or read book The Porphyrin Handbook written by Karl Kadish and published by Elsevier. This book was released on 2000 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Porphyrin Handbook, Volume 19: Applications of Phthalocyanines provides information pertinent to every aspect of the chemistry, synthesis, spectroscopy, and structure of phthalocyanines. This book examines the biology and medical implications of porphyrin systems. Organized into five chapters, this volume begins with an overview of the basic photobiology of phthalocyanines, their structure-activity relationships, mechanisms of action in a variety of biological systems, and their potential applications for various medical purposes. This text then examines the type of organization of the molecules in the solid state and the intensity of the intermolecular interactions. Other chapters consider the applications of phthalocyanines as decorative and functional materials, with emphasis on properties and structures of phthalocyanines with industrial relevance. This book discusses as well the enzyme-like catalytic functions of metal complexes derivatives and their practical applications as odor-removing systems and bacterial systems based on their effective catalytic activities. This book is a valuable resource for research scientists, engineers, and clinicians.
Download or read book Activation of Small Molecules written by William B. Tolman and published by John Wiley & Sons. This book was released on 2006-12-13 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first to combine both the bioinorganic and the organometallic view, this handbook provides all the necessary knowledge in one convenient volume. Alongside a look at CO2 and N2 reduction, the authors discuss O2, NO and N2O binding and reduction, activation of H2 and the oxidation catalysis of O2. Edited by the highly renowned William Tolman, who has won several awards for his research in the field.
