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Metal Ligand Cooperativity In Low Valent Iron Complexes For Small Molecule Activation
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Book Synopsis Metal-ligand Cooperativity in Low-valent Iron Complexes for Small Molecule Activation by : Nicolas I. Regenauer
Download or read book Metal-ligand Cooperativity in Low-valent Iron Complexes for Small Molecule Activation written by Nicolas I. Regenauer and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Low-Valent Iron and Cobalt Isocyanide Complexes by : Charles Cameron Mokhtarzadeh
Download or read book Low-Valent Iron and Cobalt Isocyanide Complexes written by Charles Cameron Mokhtarzadeh and published by . This book was released on 2017 with total page 434 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation describes the targeted attempts at the generation of transition metal species that function as precise electronic structure mimics to the well known spin triplet (S =1) metal carbonyls fragments Fe(CO)4 and CpCo(CO). These unsaturated fragments have been shown to display a wide range reactivity, and competency towards important reaction chemistry such as alkane and N2 binding, and E-H bond activation due to a unique interplay of a strong ligand field, formal dn count, and orbital symmetry, rendering these fragments primed for bond activation. Accordingly, ligand architectures that can accurately mimic the ligand field provided by CO to kinetically stabilize these fragments could provide new inroads to novel small molecule activation pathways. To this end, sterically encumbering m-terphenyl isocyanides serve as isolobal ligand surrogates for carbon monoxide (CO). Additionally isocyanides have the added benefit of providing kinetic stabilization by virtue of readily tunable isocyano-R (CN-R) group. The first section of this dissertation describes the synthesis and protonation of an encumbered tetra-isocyanide iron dianion, Na2[Fe(CNArMes2)4] (ArMes2 = 2,6-(2,4,6 --Me3C6H2)2C6H3), which serves as a platform for targeting species of the formulation Fe(CNArMes2)4. It is shown that the reactivity of the electronically unsaturated Fe(CNR)4 fragment upon protonation of Na2[Fe(CNArMes2)4] and subsequent alkylation of Na[HFe(CNArMes2)4], yields the dinitrogen stabilized species Fe(N2)(CNArMes2)4. Fe(N2)(CNArMes2)4 is shown to readily undergo intramolecular C-H activation of the ligand scaffold upon liberation N2 under ambient conditions purportedly through and insipient [Fe(CNArMes2)4] fragment. Further more, ability of Na2[Fe(CNArMes2)4] to facilitate the reductive disproportionation of CO2, in addition to CO2 capture with electrophilic silyl sources is presented culminating in a rare class of low valent Fe-aminocarbyne complexes. The second vignette of this dissertation focuses on the generation of species that mimic the formulation CpCo(L). It is shown that with less encumbering m-terphenyl isocyanides that aggregation akin to the unsaturated carbonyl congeners is realized. Use of encumbering m-terphenyl isocyanides provides access to the three memebered electron transfer series [([mu]2-CNArMes2)2[CpCo]2]n (n = 0,-1, -2). Notably, this series is the first of its kind to span all three ostensible electronic states (e.g. d8-d8, d8-d9, and d9-d9), previously unavailable with other [pi]-acidic ligand frameworks. Additionally this allows for a systematic reassessment of the metal-metal bonding within this class of dimeric species. Evidence is put forth in favor of no M-M bonding interactions occur within these systems and the integrity of the dimeric framework is in fact mitigated through a unique interplay of the metal d-manifold and the isocyanide [pi]*-system. Modulation of the steric profile of the m-terphenyl isocyanide and the Cp unit to Cp* so as to increase the steric pressure provides access to the first reported mono-nuclear Cp*Co(N2)L fragments. It is shown that these species function as viable sources of Cp*Co(CNR) for a number of bond activation processes including Si-H, H-H, and P-P bond scission. Moreover, the reactivity of these species culminates with the isolation of the second example of a structurally authenticated transition metal nitrous oxide (N2O) adduct, which exhibits an unprecedented [eta]2-(N,N) coordination mode to Co. Finally, the reduction of the encumbered Cp*Co(CNArTripp2) (CNArTripp2 2,6-(2,4,6-(i-Pr)3C6H3)2C6H3) fragment provide access to the unique dianion K2[Cp*Co≡CNArTripp2]. It is shown that the dianion K2[Cp*Co≡CNArTripp2] exhibits 3-fold bonding between Co and the isocyanide -Ciso through an extreme case of M-->(CN) [pi]*-back donation and gives rise to the first example of a Co-carbyne complex. The reactivity and electronic structure are presented for K2[Cp*Co≡CNArTripp2] and it is concluded that this reactive dianion behaves as a potent metal based nucleophile and source of [Cp*Co(CNR)]2- for a number of bond activation process.
Book Synopsis High- and Low-Valent tris-N-Heterocyclic Carbene Iron Complexes by : Carola S. Vogel
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.
Book Synopsis Activation of Small Molecules by Low Valent Corrole Metal Complexes by : Inna Luobeznov
Download or read book Activation of Small Molecules by Low Valent Corrole Metal Complexes written by Inna Luobeznov and published by . This book was released on 2007 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Activation of Small Molecules by : William B. Tolman
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.
Book Synopsis Small Molecule Activation Mediated by Metal-ligand Cooperation Via a Dearomatization/rearomatization Reaction Sequence Using Redox Active Pyridine Based Ligand-systems in Transition Metal Complexes by : Rasmus Stichauer
Download or read book Small Molecule Activation Mediated by Metal-ligand Cooperation Via a Dearomatization/rearomatization Reaction Sequence Using Redox Active Pyridine Based Ligand-systems in Transition Metal Complexes written by Rasmus Stichauer and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Small Molecule Activation of Copper and Iron Complexes with Bis(oxazoline) Ligands by : Vandana Esther Goswami
Download or read book Small Molecule Activation of Copper and Iron Complexes with Bis(oxazoline) Ligands written by Vandana Esther Goswami and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This work describes small molecule activation by copper and iron complexes with structurally and electronically modified bis(oxazoline) (BOX) ligand systems, focusing on dioxygen and nitric oxide as substrates. Dioxygen activation at low temperatures by copper(I) complexes with neutral BOX scaffolds generated the side on peroxo dicopper(II) systems that resemble the intermediates found in type III copper proteins, whereas those complexes with an anionic BOX-derived scaffold generated the bis(μ-oxido) dicopper(III) species. The bis(μ-oxido) system has recently been proposed as an active inte...
Book Synopsis Iron Chemistry of Hemilabile SNS Ligands by : Uttam Das
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.
Book Synopsis Metal to Ligand Electron Transfer for Molecular Activation and Catalysis by : Indu Vidayaratne
Download or read book Metal to Ligand Electron Transfer for Molecular Activation and Catalysis written by Indu Vidayaratne and published by . This book was released on 2010 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Synthetic and Mechanistic Studies of Small-molecule Activation at Low-valent Iron, Cobalt, and Iridium Centers by : Matthew Thomas Whited
Download or read book Synthetic and Mechanistic Studies of Small-molecule Activation at Low-valent Iron, Cobalt, and Iridium Centers written by Matthew Thomas Whited and published by . This book was released on 2009 with total page 482 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Transition Metal Complexes in Cooperative Lewis Pairs for Small Molecule Activation by : Krishna Mistry
Download or read book Transition Metal Complexes in Cooperative Lewis Pairs for Small Molecule Activation written by Krishna Mistry and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Iron Catalysis in Organic Chemistry by : Bernd Plietker
Download or read book Iron Catalysis in Organic Chemistry written by Bernd Plietker and published by John Wiley & Sons. This book was released on 2008-09-08 with total page 295 pages. Available in PDF, EPUB and Kindle. Book excerpt: This first comprehensive book to cover this exciting field also deals with the biological aspects, such as enzymes with iron. Following an introduction, this handy reference and handbook goes on to deal with reductions, oxidations of C, H- and C=C bonds, oxidative allylic oxygenation and amination, the oxidation of heteroatoms, cross coupling reactions, aromatic and nucleophilic substitutions, addition to carbonyl compounds, and cyclisations as well as ring opening reactions. The chapters are clearly classified according to the reaction type, allowing readers to quickly locate the desired information.
Book Synopsis Ligand Design Considerations for the Activation of Small Molecules by : Sonja Marie Peterson
Download or read book Ligand Design Considerations for the Activation of Small Molecules written by Sonja Marie Peterson and published by . This book was released on 2012 with total page 147 pages. Available in PDF, EPUB and Kindle. Book excerpt: In Nature, the effective control of both the primary and secondary coordination spheres by metal-containing proteins has led to highly efficient and selective catalysts. Much effort has been put forth by the synthetic chemistry community to design complexes that explore the effects of modifying the primary coordination sphere. However, understanding the implications of both coordination spheres together is necessary to ultimately lead to the development of effective synthetic complexes for small molecule activation. For the research described herein, inspiration from biology has led to the design and preparation of ligands, paying special attention to both environments to meet the specific requirements of the small molecules targeted. Chapter 2 discusses the design and synthesis efforts of two new tripodal and tridentate ligands and complexes that feature both a redox-active primary coordination sphere and contain intramolecular H-bond donors in the secondary coordination sphere. This project was in collaboration with the laboratory of Alan Heyduk. Chapter 3 describes the synthesis and characterization of [Co II[superscript] H2bupa]− and [Ni II[superscript] H2bupa]− complexes. The reactivity of both of these complexes with dioxygen was explored in order to detect intermediates during activation yielding proposed Co III[superscript] -superoxo and Ni III[superscript] -hydroxo species. [Co II[superscript] H2bupa]− was also found to reduce dioxygen to water. Water measurements were carried out for [Co II[superscript] H2bupa]− and [Mn II[superscript] H2bupa]− in the presence of an internal standard. The turnover number for these complexes was determined and will also be discussed. Chapter 4 features the synthesis of a new tripodal ligand, H3btspa. It contains the carboxyamidopyridine group reminiscent of H5bupa, but contains two sufonamido groups capable of acting as H-bond acceptors. Upon deprotonation it ready forms complexes with Mn II[superscript], Fe II[superscript], Co II[superscript], and Zn II[superscript] salts. The stability of these complexes will also be described. Chapter 5 discusses nitrogen-containing complexes made from [Fe II[superscript] MST]-. Both the Fe II[superscript] and Fe III[superscript]-ammine complexes were synthesized along with the Fe II[superscript] -hydrazine complex. Attempts to deprotonate the Fe III[superscript]-ammine complex resulted in the reformation of the Fe II[superscript] ammine complex, leading to the proposal of a transient Fe III[superscript]-amido intermediate. Attempts to perform amination chemistry from the Fe II[superscript] and Fe III[superscript]-ammine complexes will also be highlighted.
Book Synopsis Synthesis and Characterization of Transition Metal Complexes with Bulky Tin Ligands for Application in Small Molecule Activation by : Veeranna Yempally
Download or read book Synthesis and Characterization of Transition Metal Complexes with Bulky Tin Ligands for Application in Small Molecule Activation written by Veeranna Yempally and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The role of bulky tin ligands in the stabilization of transition metal complexes with electronic unsaturation has been studied to understand the mode of binding of small molecules at an unsaturated metal center. We were able to isolate electronically unsaturated Pt-Sn bimetallic complexes effective in the reversible activation of small molecules including CO, H2, C2H4, and NH3 at room temperature. We have examined the effect of the modification of ligands in Pt-Sn bimetallic complexes for the activation of small molecules and have observed that the Pt(SnBut3)2(CNBut)2 bimetallic complex reversibly activates hydrogen at room temperature both in the solid state and in solution. Similarly, we have also prepared bimetallic Pt-Sn complexes with an NHC carbine ligand which were also shown to activate hydrogen and alkenes reversibly. A bimetallic Fe-Sn cluster complex, Fe2 ([mu]-SnBut2)2(CO)8, was synthesized from the reaction of But3SnH with the Fe2(CO)9 and shown to be selective at activating the benzylic C-H bond of alkylaromatic solvent molecules. The new complexes containing tin have been characterized spectroscopically to gain an insight into the reaction mechanism involved in small molecule activation.
Download or read book Iron Catalysis written by Bernd Plietker and published by Springer Science & Business Media. This book was released on 2011-01-05 with total page 227 pages. Available in PDF, EPUB and Kindle. Book excerpt: Juan I. Padrón and Víctor S. Martín: Catalysis by means of Fe-based Lewis acids; Hiroshi Nakazawa*, Masumi Itazaki: Fe–H Complexes in Catalysis; Kristin Schröder, Kathrin Junge, Bianca Bitterlich, and Matthias Beller: Fe-catalyzed Oxidation Reactions of Olefins, Alkanes and Alcohols: Involvement of Oxo- and Peroxo Complexes; Chi-Ming Che, Cong-Ying Zhou, Ella Lai-Ming Wong: Catalysis by Fe=X Complexes (X=NR, CR2); René Peters, Daniel F. Fischer and Sascha Jautze: Ferrocene and Half Sandwich Complexes as Catalysts with Iron Participation; Markus Jegelka, Bernd Plietker: Catalysis by Means of Complex Ferrates.
Book Synopsis Phosphinoamide Ligand Supported Heterobimetallic Complexes Featuring Metal-metal Bonding and Their Application in Small Molecule Activation by : Bing Wu
Download or read book Phosphinoamide Ligand Supported Heterobimetallic Complexes Featuring Metal-metal Bonding and Their Application in Small Molecule Activation written by Bing Wu and published by . This book was released on 2017 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Organometallic Chemistry and Catalysis of Iron with Noninnocent Ligands by : Qiu Ming Liang
Download or read book Organometallic Chemistry and Catalysis of Iron with Noninnocent Ligands written by Qiu Ming Liang and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The development of iron catalysts is attractive owing to the ready availability, relatively low cost and low toxicity of iron, its oxides and many of its salts comparing to noble metals. Iron complexes are capable of not only the standard two-electron processes, but also single electron transfer reactions that are less prevalent in noble metal chemistry. In Nature, many iron-containing metalloenzymes make use of the noninnocent properties of ligands coordinated to the iron center in their active sites. Inspired by this, my thesis examines the fundamental coordination chemistry and catalysis of iron complexes using noninnocent ligands. The first part (Chapter 2−4) of my thesis describes the synthesis and reactivity of iron complexes bearing bidentate picolyl−NHC (NHC = N-heterocyclic carbene) ligands In Chapter 2, the coordination chemistry and reactivity of picolyl−NHC iron and ruthenium complexes were explored, which includes the diverse coordination modes of picolyl−NHC ligands upon deprotonation, metal-ligand cooperation, and small molecule binding. In Chapter 3, an unusual ligand rearrangement of a deprotonated picolyl−NHC ligand on iron and ruthenium was investigated. Chapter 4 describes the iron-catalyzed geminal-specific alkyne dimerization. The second part describes (Chapter 5) the synthesis and reactivity of iron complexes bearing bidentate o-phenylenediamide ligands including the syntheses of biomimetic [2Fe2S] clusters and their catalytic reactivity in catalytic silylation of dinitrogen.
