Download or read book Synthesis Characterization and Reactivity of Iron Complexes with N donor Ligands in Relation to Oxygenation of Hydrocarbons written by Remle Çelenligil-Çetin and published by . This book was released on 2004 with total page 766 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis Characterization and Reactivity Studies of Iron Complexes Supported by the Redox active ONO Ligand written by Janice Lin Wong and published by . This book was released on 2014 with total page 123 pages. Available in PDF, EPUB and Kindle. Book excerpt: The work reported herein primarily focuses on the development of new platforms for multi-electron reactivity using iron complexes supported by a redox-active pincer-type ligand. This dissertation details the synthesis, characterization, and reactivity of iron complexes coordinated to the redox-active [ONO] ([ONO]H3 = bis(3,5-di-[tert]-butyl-2-phenol)amine) ligand. Chapter 1 provides a general background on ligand-centered and metal-centered redox reactivity. Specifically, the characteristics of redox-active ligands and their ability to promote multi-electron reactivity at redox-inert metal centers is presented. In addition, iron-catalyzed organic transformations in which the metal center undergoes redox changes is also discussed. Finally, ligand-enabled redox reactions mediated by iron complexes containing redox-active ligands is described. Chapter 2 reports on the complexation of bis(3,5-di-[tert]-butyl-2-phenoxy)amine, [ONHO], and the redox-active [ONO] ligands by iron centers to afford a new family of iron complexes. Characterizations of each compound through a battery of analytical techniques reveal the oxidation states of the metal center and ligand. Furthermore, the electronic properties of each complex were investigated in order to evaluate their potential to facilitate multi-electron reactivity. Chapter 3 details the reactivity of the [ONO]Fe platform. Metathesis reactions are conducted with [ONO [superscript q] Fe [superscript III] X2 (X = Cl, N[SiMe3]2 complexes, demonstrating the capability of the fully-oxidized [ONO [superscript q]−1 to act as a two-electron acceptor to generate the fully reduced [ONO [superscript cat]3− that is coordinated to an iron(III) center. Similarly, oxidation of [ONO[superscript cat] Fe [superscript III] (py)3 (py = pyridine) using dihalogens result in two-electron oxidations of the tridentate ligand while the metal oxidation state remains the same. These redox reactions showcase the ability of the [ONO] ligand platform to undergo reversible two-electron oxidation state changes, allowing multi-electron reactivity to occur at the iron center. The synthesis and characterization of two novel bimetallic complexes of the form [ONO]M'[ONO]2 M (M' = Fe, Zn; M = Fe) are presented in Chapter 4. The rich redox profiles of both complexes suggest that they can potentially impart unique cooperative bimetallic reactivity. The synthetic techniques developed to prepare these complexes lay the foundation for a general method to access new bimetallic combinations that could be promising for multi-electron reactivity. Finally, Chapter 5 discusses the synthesis, characterization, and electronic comparisons between two homoleptic tris-iminosemiquinonate chromium(III) compounds. While one is coordinated to three N,N'-bis(3,5-dimethylphenyl)acenapthenediimino-semiquinonate, (dmp-ADI [superscript sq])1−, ligands, the other contains three N,N'-bis(3,5-dimethylphenyl)phenanthrenediimino-semiquinonate, (dmp-PDIsq)1− ligands. The differences in the electronic properties between each complex likely stems from variation in the diimine ligand backbones. However, further investigation is required to completely understand the complicated behaviors of such complexes, both of which apparently exhibit intramolecular anti-ferromagnetic properties.
Download or read book High and Low Valent tris N Heterocyclic Carbene Iron Complexes written by Carola S. Vogel and published by Springer Science & Business Media. This book was released on 2012-02-03 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt: Carola Vogel’s PhD thesis focuses on the synthesis, and structural and spectroscopic characterization of the first high valent iron nitride complexes. In her interdisciplinary and collaborative research Carola also describes the reactivity studies of a unique iron (V) nitride complex with water. These studies show that quantitative yields of ammonia are given at ambient conditions. High valent iron nitride and oxo species have been proposed as key intermediates in many bio-catalytic transformations, but until now these species have proven exceedingly challenging to isolate and study. Iron complexes in high oxidation states can thus serve as models for iron-containing enzymes to help us understand biological systems or aid our development of more efficient industrial catalysts.
Download or read book Design Synthesis and Characterization of New Ligands and Activators for the Oligomerization of Ethylene by Iron Complexes written by Adrien Boudier and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes the development of new catalytic systems based upon iron complexes and their reactivity toward ethylene. First, we focused our interest on the synthesis of iron(III) precursors chelated by monoanionic ligand. Those complexes were obtained either by reaction of the monoanionic ligand with FeCl3 or through oxidation of the iron(II) complex. The second reaction led to binuclear complexes. Then, another aim of the thesis was to design new well-defined cocatalysts for the activation of iron complexes. The study of the reaction between an alcohol and the trimethylaluminum allowed us to reach this aim. Aluminum complexes adopted either a binuclear framework or a trinuclear one, depending on the nature of alcohol reagent. Besides this work, new iron(II) and nickel(II) complexes chelated by imino-imidazole ligands bearing a pendant donor function L were synthesized. All complexes have been evaluated for the oligomerization of ethylene in the presence of EtAlCl2 or MAO as cocatalyst. Only nickel complexes were active toward ethylene transformation.
Download or read book Synthesis Characterization and Reactivity of Transition metal Dihydrogen Complexes of Fe Ru and W written by Lori Ruth Ann Stepan Van der Sluys and published by . This book was released on 1991 with total page 714 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Synthesis Characterization and Study of Transition Metal Complexes for the Oxidation and Activation of Hydrocarbons written by Robert Edward Blake and published by . This book was released on 1996 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis of Iron N Heterocyclic Carbene Complexes and Their Application in the Oxidation Catalysis of Hydrocarbons written by Andreas Daniel Raba and published by . This book was released on 2014 with total page 241 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis Structure and Reactivity of Transition Metal Complexes Containing P O and N donor Ligands written by Vladimir F. Kuznetsov and published by . This book was released on 2001 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Vanadium Catalysis written by Manas Sutradhar and published by Royal Society of Chemistry. This book was released on 2020-11-05 with total page 526 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vanadium is one of the more abundant elements in the Earth’s crust and exhibits a wide range of oxidation states in its compounds making it potentially a more sustainable and more economical choice as a catalyst than the noble metals. A wide variety of reactions have been found to be catalysed by homogeneous, supported and heterogeneous vanadium complexes and the number of applications is growing fast. Bringing together the research on the catalytic uses of this element into one essential resource, including theoretical perspectives on proposed mechanisms for vanadium catalysis and an overview of its relevance in biological processes, this book is a useful reference for industrial and academic chemists alike.
Download or read book Synthesis and Reactivity of Water soluble N donor Ligand Metal Complexes Capable of Promoting the Hydrolysis of Organophosphorous Substrates written by Navdeep Kaur Bilon and published by . This book was released on 2009 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Iron Chemistry of Hemilabile SNS Ligands written by Uttam Das and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The development of abundant and economical first-row transition metal-based catalysts is an appealing area of research for efficient and selective chemical transformations. In this context, iron complexes are highly desirable as they feature a range of accessible oxidation states allowing for transfer of one or two electrons to or from a substrate. Therefore, over the past two decades, many iron-based catalysts have been developed, extensively studied, and exploited for catalysis ranging from oxidation and reduction to C-C bond forming reactions. In homogeneous transition metal catalysis, the ligand plays a vital role in determining activity and selectivity of the above stated catalytic reactions. Some key features of ligands that support both stoichiometric and catalytic reactions of metal complexes include: 1) strong chelation ability to metals, 2) tunability of donor atoms, 3) strong field ligands such as phosphine, phosphite, CO, and hydride favoring low-spin complexes, 4) hemilability allowing substrate activation via reversible dissociation of one donor atom, and 5) redox-activity enabling donation or accepting of electrons, thus avoiding a change of metal oxidation state. To this end, bifunctional ligands containing the above described properties have emerged as important elements in chemical synthesis and in catalysis. Iron and other transition metal complexes containing multidentate bifunctional ligands have recently been shown to activate small molecules and catalyze a number of chemical transformations with activity and selectivity typical of more well-studied precious metals. The objective of this thesis is to further advance the field of bifunctional ligands by preparing new sterically svelte tridentate ligands with a mixture of hard nitrogen and soft sulfur donors and to investigate their iron chemistry. The overall goal is to then explore the utility of these iron complexes as potential bifunctional catalysts. Chapter 2 describes a one-step synthesis of a new SMeNHS ligand in excellent yield that undergoes ring-opening on treatment with Fe(OTf)2 affording a thiolate-bridged, trinuclear iron complex, [Fe3(μ2-SMeNS−)4](OTf)2. The structure, spectroscopic, magnetic, and computational studies of this iron complex are provided along with its solvent-dependent reactivity towards monodentate donor ligands that yields both dinuclear and mononuclear derivatives. Chapter 3 describes the formation of an electron-rich Fe(II) thiolate complex, [Fe(SMeNS)(PMe3)3](OTf) and its substitution reactivity with both mono- and bidentate donor ligands. On heating this complex, an oxidative thioether Caryl-S bond cleavage is observed, leading to a cationic Fe(III)-CNS thiolate analog. Reduction of this Fe(III) species with cobaltocene yielded a neutral Fe(II)-CNS thiolate complex. To investigate the bifunctional activity of these Fe(II) complexes, both Fe(II)-SNS and -CNS species were assessed as precatalysts for amine-borane dehydrogenation. Chapter 4 employs the SMeNHS ligand in formation of a neutral, imine-coupled Fe-N2S2 complex that serves as an efficient and selective aldehyde hydroboration catalyst using pinacolborane. A reaction profile kinetic analysis implicates the hemilability and redox-active properties of this complex. Chapter 5 introduces the new unsymmetrical amine ligand, SMeNHSMe, and details its iron chemistry with formation of a pseudooctahedral Fe(II) bis(amido) complex. The Mössbauer spectra, MCD study, and DFT calculations support formation of a minor five-coordinate isomer in solution due to the hemilability of the six-membered ring thioether group. Reactivity studies of this Fe(II) species with a variety of donor ligands confirmed this lability and protonation at nitrogen yielded a cationic Fe(II) amine-amido complex. Reaction of the latter with the tridentate phosphine, triphos, gave a 16e-, low-spin, square-pyramidal Fe(II) complex that proved to be a robust precatalyst that is more active for dehydrogenation of dimethylamine-borane vs. ammonia-borane. Formation of a monohydride catalyst resting state under these reaction conditions is suggestive of a bifunctional activation pathway. Finally, Chapter 6 concludes the outcomes of the iron chemistry of hemilabile SNS ligands and discusses future directions and opportunities to extend these ligand systems to other transition metals. The knowledge gained by the stoichiometric and catalytic reactivity of iron-SNS complexes presented herein contributes to our understanding of bifunctional catalysis. With the increasing demand for base metal catalysts in chemical industry for efficient and selective synthesis of value-added chemicals, iron SNS complexes could offer economical, active, and selective catalyst precursors.
Download or read book Iron and Cobalt Catalysts written by Wilson D. Shafer and published by MDPI. This book was released on 2020-06-23 with total page 414 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the turn of the last century when the field of catalysis was born, iron and cobalt have been key players in numerous catalysis processes. These metals, due to their ability to activate CO and CH, haev a major economic impact worldwide. Several industrial processes and synthetic routes use these metals: biomass-to-liquids (BTL), coal-to-liquids (CTL), natural gas-to-liquids (GTL), water-gas-shift, alcohol synthesis, alcohol steam reforming, polymerization processes, cross-coupling reactions, and photocatalyst activated reactions. A vast number of materials are produced from these processes, including oil, lubricants, waxes, diesel and jet fuels, hydrogen (e.g., fuel cell applications), gasoline, rubbers, plastics, alcohols, pharmaceuticals, agrochemicals, feed-stock chemicals, and other alternative materials. However, given the true complexities of the variables involved in these processes, many key mechanistic issues are still not fully defined or understood. This Special Issue of Catalysis will be a collaborative effort to combine current catalysis research on these metals from experimental and theoretical perspectives on both heterogeneous and homogeneous catalysts. We welcome contributions from the catalysis community on catalyst characterization, kinetics, reaction mechanism, reactor development, theoretical modeling, and surface science.
Download or read book Synthesis Characterization and Reactivity of Dinuclear Rhodium II Complexes Containing Nitrogen Donor Ligands written by Charles A. Crawford and published by . This book was released on 1995 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Preparation Characterisation and Reactivity of Low Oxidation State d Block Metal Complexes Stabilised by Extremely Bulky Amide Ligands written by Jamie Hicks and published by Springer. This book was released on 2016-10-24 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes the synthesis and characterization of numerous metal-metal bonded complexes that are stabilized by extremely bulky amide ligands. It provides a comprehensive overview of the field, including discussions on groundbreaking complexes and reactions, before presenting in detail, exciting new findings from the PhD studies. The thesis appeals to researchers, professors and chemistry undergraduates with an interest in inorganic and/or organometallic chemistry.
Download or read book Synthesis and Applications of High spin Iron Tetra azamacrocyclic Complexes written by Samantha Brewer Ochoa and published by . This book was released on 2018 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt: Herein we describe the synthesis, characterization, and role several iron complexes in the coupling of pyrrole and phenylboronic acid to form 2-phenylpyrrole. The oxidation state and spin state of the iron complexes were characterized using X-ray crystallography, UV-vis absorbance spectroscopy, cyclic voltammetry, and in some cases electron paramagnetic reasonance spectroscopy. Furthermore, the results indicate that the iron(III) complexes are essential for catalytic and regioselective production of the 2-phenylpyrrole product. The complexes were compared to evaluate the effect of five properties on catalyst reaction yields: the coordination requirements of the catalyst, half-potential, topological constraint/rigidity, N-atom modification(s), increasing oxidative stability of the complex, and geometric parameters. The need for two labile cis-coordination sites was confirmed based on a 42% decrease in catalytic reaction yield observed when complexes containing penta-dentate ligands were used in place of complexes with tetra-dentate ligands. A strong correlation between iron(III/II) redox potential and catalytic reaction yields was also observed, with [Fe2+L6(Cl)2] providing the highest yield (81%, -405 mV). A Lorentzian fitting of redox potential versus yields predicts that these catalysts can undergo more fine tuning to further increase yields. Interestingly, the remaining properties explored did not show a direct, strong relationship to catalytic reaction yields. Furthermore, the role of the sacrificial oxidant, the lack of radical participation, and the formation of μ-oxodiiron species was established leading to a more detailed mechanistic cycle. Finally, a library of five pyclen-based ligands have been developed for use as iron and europium chelators. A preliminary investigation into iron PCTA complexes indicate that the iron center can bind to all seven of the ligand donors, however, the iron complex does not afford a CEST signal. Establishing that heptadentate ligands containing carboxylic acid pendent arms are not ideal for the developments of iron PARACEST agents.
Download or read book Synthesis and Reactivity of PtII Complexes with Secondary Sphere N H Moieties written by Braden A. Zahora and published by . This book was released on 2019 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt: Direct transformations of abundant hydrocarbons into higher valued products would circumvent energy intensive processes, reforming the chemical industry. Late transition metals, particularly platinum, are known to selectively convert alkanes into functionalized products. However, a practical method with an economically viable oxidant has yet to be discovered. New methods for alkane activation may yield further advances towards this goal. This dissertation focuses on how platinum methyl complexes with ligand-based protons can form methane, the microscopic reverse of methane activation. Chapter 1 provides an introduction on the need to develop new methods to functionalize hydrocarbons. Furthermore, a survey of the literature with respect to how late metal complexes can undergo productive reactivity with substrates which are deemed necessary for practical alkane partial oxidation is presented. Chapter 2 focuses on the synthesis and reactivity of 5-(6-methyl-2-pyridyl)-3-tert-butylpyrazolate (NN[superscript]Me) and 2-(5-tert-butylpyrazol-3-yl)-6 (diethylaminomethyl)pyridine (NNN[superscript]Et) ligated Pt[superscript]II complexes. Once formed, conditions necessary for methane formation were found and it was determined that the ligand-based N-H was not involved in methane formation. Chapter 3 explores synthesis and reactivity of 5-tert-butyl-1,3-bis(pyrazol-3-yl)pyridine (NNN) and 5-tert-butyl-1,3-bis(pyrazol-3-yl)benzene (NCN) ligated Pt[superscript]II-alkyl complexes with electrophilic reagents. It was found that tridentate ligated pyrazolate Pt[superscript]II-R systems can undergo protonation at the ligand if there is a weak pyridine trans donor (vs strong phenyl trans donor) to the Pt[superscript]II-R moiety. However, reactivity with methyl iodide occurred at the metal first, with further ligand methylation spectroscopically observed for the NNN ligated Pt-CH3 complex. Chapter 4 discusses the synthesis and characterization of bis(phosphino)amine ligated Pt[superscript]II complexes, which contained a ligand-based N-H. Taking advantage of unfavorable steric congestion of bulky Ph groups on the ligand, methane formation was observed from thermolysis reactions of a bis(phosphino)amine ligated Pt(CH3)2. Although additional characterization of the resulting metal-containing product is required, it appears that methane was formed through cooperation of the ligand-based N-H moiety and the Pt-CH3 ligand.
Download or read book The Synthesis Characterisation and Reactivity of Iron III Complexes with N 2 Pyridylmethyl iminodiacetate written by Bob Banik and published by . This book was released on 1995 with total page 205 pages. Available in PDF, EPUB and Kindle. Book excerpt:
