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Book Synthesis Reactions and Properties of Iron Cobalt and Nickel Complexes Containing Some P S chelating Ligands and Trimethylphosphine

Download or read book Synthesis Reactions and Properties of Iron Cobalt and Nickel Complexes Containing Some P S chelating Ligands and Trimethylphosphine written by Hamdi Bennour and published by . This book was released on 2010 with total page 159 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book The Chemistry of Iron Cobalt and Nickel

Download or read book The Chemistry of Iron Cobalt and Nickel written by David Nicholls and published by . This book was released on 1975 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Mechanistic Investigations Into the Thermal C C Bond Forming Cyclization of Metal Pyridine Enamide Complexes and the Synthesis and Reactivity of Cationic and Neutral Iron IV Alkylidene Complexes

Download or read book Mechanistic Investigations Into the Thermal C C Bond Forming Cyclization of Metal Pyridine Enamide Complexes and the Synthesis and Reactivity of Cationic and Neutral Iron IV Alkylidene Complexes written by Brian Lindley and published by . This book was released on 2016 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: A series of first row transition metal pyridine-enamide complexes has been synthesized. In the course of reactivity studies, it was discovered that heating a solution of the cobalt bis(pyridine-enamide) pyridine adduct resulted in intraligand CC coupling to form an indolamide ligand. Control experiments with the corresponding lithium pyridine-enamide afforded the same indolamide. In order to probe the mechanism of cyclization, deuterium labeling experiments for the lithium pyridineenamide compound were conducted. Careful kinetics measurements supported a mechanism consisting of reversible hydrogen transfer followed by rate-determining CC bond formation, in accord with computational results. Iron(II) complexes bearing cyclometalated benzyldialkylphosphine ligands were synthesized via a salt metathesis approach by treating FeCl2(PMe3)2 with two equivalents of (2-lithiobenzyl)diphenyl- and (2-lithiobenzyl)dicyclohexylphosphine reagents. For the phenyl derivative, a 6-coordinate diamagnetic complex containing two chelating phosphine ligands and two trimethylphosphine ligands was obtained. Contrarily, for the cyclohexyl derivative, a 5-coordinate complex containing two chelating phosphines and one molecule of trimethylphosphine was obtained. This compound is paramagnetic with an S = 1 ground state. Efforts to synthesize Fe(IV) alkylidenes by treating these Fe(II) complexes with diphenyldiazomethane were ultimately unsuccessful. An iron(II) vinyl complex was synthesized by reaction of cis-Me2Fe(PMe3)4 with a 2-propynylaniline benzylidene ligand. Protonation of this complex with [H(OEt2)2]BArF4 (BArF4 = B(3,5-(CF3)2C6H3)4) gave access to a cationic Fe(IV) alkylidene complex. By treating this complex with different anionic nucleophiles, a rare series of neutral Fe(IV) alkylidene complexes was obtained. In addition, treatment of the cationic alkylidene complex with MeMgCl afforded a novel Fe(IV) methyl complex. Attempts at catalyzing olefin metathesis with both the cationic and neutral alkylidene complexes proved unsuccessful, likely due to recalcitrant phosphine dissociation and the sterics at the alkylidene carbon.

Book Cyclometalation and Bicyclometalation Reactions of Trimethylphosphine Supported Iron Cobalt and Nickel Compounds Via C H Activation with Imine and Carbonyl Anchoring Groups

Download or read book Cyclometalation and Bicyclometalation Reactions of Trimethylphosphine Supported Iron Cobalt and Nickel Compounds Via C H Activation with Imine and Carbonyl Anchoring Groups written by Şebnem Camadanlı and published by . This book was released on 2005 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Oxidation State Roulette

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.

Book Cobalt and Nickel Based Organometallic Chemistry of the N Phenylenes

Download or read book Cobalt and Nickel Based Organometallic Chemistry of the N Phenylenes written by Robin Padilla and published by . This book was released on 2010 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation explores the synthesis and study of linear [N]phenylene cobalt complexes and the reactions of angular [N]phenylenes with nickel catalysts. Chapter 1 contains a general introduction to the properties of the [N]phenylenes as well as a brief overview of earlier organometallic [N]phenylene chemistry with an emphasis on work directly related to that presented in the subsequent chapters. Chapter 2 presents studies regarding first ever examples of photo-induced, thermally reversible haptotropic shifts in linear [3]phenylene cyclopentadienyl cobalt (CpCo) complexes. In these reactions, the CpCo fragment migrates from one cyclobutadiene ring to another upon exposure to UV irradiation. Heating the photoisomer complexes causes the metal fragment to return to its original position. Aside from the novelty of an eta-4:eta-4 cyclobutadiene migration, the photo-induced, thermally reversible nature of these systems makes them attractive as candidates for photostorage devices and/or molecular switches. The syntheses and structural studies of the linear phenylene(CpCo) complexes are discussed. In addition to the experimental work, computational studies on the haptotropic shift are also included. Closely related work, such as the observation of an intermediate haptotropic species at low temperature and the preparation of a linear [3]phenylene complex containing two CpCo units bound to the ligand, is also discussed. Chapter 3 describes nickel-catalyzed insertion reactions with angular phenylenes as a method for preparing derivatives of [N]phenacenes, a class of polycyclic aromatic hydrocarbons that are of interest in organic electronic applications. Previous work regarding nickel insertion reactions with biphenylene is mentioned. Nickel-catalyzed insertion reactions with angular [3]- and [4]phenylene are then described. Mechanistic studies, both experimental and computational, are discussed. The results from these studies were used to optimize the reaction to produce [N]phenacenes as the major products of these insertion reactions. Chapter 4 contains experimental details relating to chapters two and three. General experimental considerations, synthetic procedures, crystallographic, and computation data are presented. Relevant references are also included in this chapter.

Book Synthesis of New Iron and Nickel Complexes

Download or read book Synthesis of New Iron and Nickel Complexes written by Anthony Kermagoret and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: My Ph-D thesis concerns the study of the catalytic oligomerization reaction with nickel, iron and cobalt complexes coordinated by N-O, P-N, N-P-N, P-O and P-N-P type ligands with a N donor atom represented by an oxazoline or a pyridine heterocycle. These complexes activated by a cocatalyst such as MAO or AlEtCl2 showed high activities and a high selectivity of C4 olefins in ethylene oligomerization. The nickel complexes with P-N chelates showed a high impact of the P substituents on the oligomerization selectivities. Moreover, the crystallographic studies on nickel complexes coordinated by N-O and P-N type ligands showed the formation of mono-, di- and tetranuclear complexes. The cobalt, iron and palladium complexes with N-P-N ligands highlighted original N-N, P-N or N-P-N coordination modes of the ligands influenced by the ligand substituents and the metal center.

Book Synthesis and Study of Coordination Compounds of Cobalt Copper Palladium and Nickel with Polydentate Ligands Containing Sulfur

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.

Book Nickel and Cobalt catalyzed Hydrofunctionalization Reaction of Alkene

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 Synthesis and Characterization of Iron Dinitrosyl Complexes with Nitrogen Containing Chelating Ligands

Download or read book Synthesis and Characterization of Iron Dinitrosyl Complexes with Nitrogen Containing Chelating Ligands written by Derrick A. Diego and published by . This book was released on 2014 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Three new [Fe-NO]1U+007b complexes coordinated with nitrogen chelating ligands have been synthesized and characterized. The new synthesized complexes are dinitrosyl(2-2'-biquinoline)iron(O), dinitrosyl(2,2' -bipyridine 4,4' -dimethyl)iron(0), and dinitrosy 1(2,2'-bipyridine 4,4' -diphenyl)iron(0). Each complex is synthesized utilizing a common starting material, dinitrosyldicarbonyliron(0), (Fe(NO)2(CO)2). Reaction conditions are in an inert atmosphere at ambient temperature and pressure. The characterizations of these molecules are done with ultraviolet visible spectroscopy, infrared spectroscopy, and single crystal X-ray diffraction. Ultraviolet visible spectroscopy display metal ligand charge transfers between 250-550 nm. Peaks below this are due to intraligand transitions from the chelating ligands. Infrared spectroscopy data reveal that NO stretching frequencies shift to lower wavenumbers when compared to Fe(NO)2(CO)2 due to its better U+0076-donating abilities of the nitrogen chelating ligands. Single crystal X-ray diffraction data show that all complexes are pseudo tetrahedral in an attracto conformation.

Book N Metallocenophanes and Polymetallocenes of Iron Cobalt and Nickel

Download or read book N Metallocenophanes and Polymetallocenes of Iron Cobalt and Nickel written by Rebecca Alice Musgrave and published by . This book was released on 2016 with total page 634 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Synthesis of Iron Cobalt Nickel and Copper

Download or read book Synthesis of Iron Cobalt Nickel and Copper written by Steven Douglas McKee and published by . This book was released on 1985 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book The Chemistry of Iron Cobalt and Nickel

Download or read book The Chemistry of Iron Cobalt and Nickel written by and published by . This book was released on 1973 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt: