Download or read book Elucidating the Electronic Structure of Transition Metal Complexes Featuring Redox Active Ligands written by Linus Kai Ho Chiang and published by . This book was released on 2014 with total page 187 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis a number of projects involving the design and characterization of complexes bearing redox active ligands are described. Focusing on the phenolate containing ligands, the properties and electronic structure of their corresponding metal complexes were studied by a series of experimental (i.e. electrochemistry, UV-Vis-NIR, EPR, rR etc.) and theoretical (DFT) methods. Specifically, the redox processes of these metal complexes were tuned by varying the para-ring substituents. In one study, nickel-salen (salen is a common abbreviation for N2O2 bis-Schiff-base bis-phenolate ligands) complexes were investigated, where the oxidation potentials of the ligand were predictably decreased as the electron donating ability of the para-ring substituents was increased (NMe2 > OMe > tBu > CF3). Interestingly, the oxidation of these geometrically-symmetric complexes afforded an asymmetric electronic structure in a number of cases, in which the ligand radical was localized on one phenolate rather than delocalized across the ligand framework. This difference in electronic structure was found to be dependent on the electron donating ability of the substituents; a delocalized ligand radical was observed for electron-withdrawing substituents and a localized ligand radical for strongly donating substituents. These studies highlight that para-ring substituents can be used to tune the electronic structure (metal vs. ligand based, localized vs. delocalized radical character) of metallosalen complexes. To evaluate if this electronic tuning can be applied to the metal center, a series of cobalt complexes of these salen ligands were prepared. Indeed, the electronic properties of the metal center were also significantly affected by para-ring substitution. These cobalt-salen complexes were tested as catalysts in organometallic radical-mediated polymerizations, where the most electron rich complexes displayed the best conversion rates. With a firm understanding of the role that the para-ring substituent can play in influencing the electronic structure and reactivity of metallosalen complexes in catalysis, two novel iron complexes, which contain a number of redox active phenolate fragments, were prepared. In addition, these iron-complexes feature a chiral bipyrrolidine backbone. Ligands with this chiral diamine backbone bind metals ions diastereoselectively owing to its increased rigidity, which is critical to stereoselectivity in catalysis. A symmetric (with two phenolates) ligand was prepared by reported methods, and a novel route to synthesize an asymmetric ligand (one phenolate and one pyridine) from symmetric starting materials was established. The neutral iron-complexes were found to be high spin (S = 5/2), and can undergo ligand based oxidation to form an antiferromagnetically-coupled (Stotal = 2) species. The results presented will serve as the basis for catalyst development using complexes of similar ligands.
Download or read book Controlling Redox Processes in Metal Complexes and Multifunctional Materials written by Khrystyna Herasymchuk and published by . This book was released on 2020 with total page 207 pages. Available in PDF, EPUB and Kindle. Book excerpt: Transition metal complexes incorporating redox-active ligands have the potential to facilitate controlled multielectron chemistry, enabling their use in catalysis and energy storage applications. Moreover, the use of transition metal complexes containing redox-active ligands has been extended to two- (2D) and three-dimensional (3D) materials, such as supramolecular assemblies (i.e., metallacycles, molecular cages, or macrocycles) and metal-organic frameworks (MOFs) for catalytic, magnetic, electronic, and sensing applications. Salens (N2O2 bis(Schiff-base)-bis(phenolate) are an important class of redox-active ligands, and have been investigated in detail as they are able to stabilize both low and high metal oxidation states for the above-mentioned applications. The work in this thesis focuses on the synthesis and electronic structure elucidation of metal salen complexes in monomeric form, as discrete supramolecular assemblies and 3D MOFs. Structural and spectroscopic characterization of the neutral and oxidized species was completed using mass spectrometry, cyclic voltammetry, X-ray diffraction, NMR, UV-Vis-NIR, and EPR spectroscopies, as well as theoretical (DFT) calculations. Chapter 2 discusses the synthesis and electronic structure evaluation of a series of oxidized uranyl complexes, containing redox-active salen ligands with varying para-ring substituents (tBu, OMe, NMe2). Chapters 3 and 4 discuss the incorporation of a redox-active nickel salen complex equipped with pyridyl groups on the peripheral positions of the ligand framework into supramolecular structures via coordination-driven self-assembly. The self-assembly results in formation of a number of distinct metallacycles, affording di-, tetra-, and octa-ligand radical species. Finally, the design, synthesis, and incorporation of metal salen units into MOFs is discussed in Chapter 5. Preliminary assembly and oxidation experiments are presented as an opportunity to explore the redox-properties of salen complexes incorporated into a solid-state 3D framework. Overall, the work described in this thesis provides a pathway for salen ligand radical systems to be used in redox-controlled host-guest chemistry, catalysis, and sensing.
Download or read book Molecular Electronic Structures of Transition Metal Complexes I written by David Michael P. Mingos and published by Springer Science & Business Media. This book was released on 2012-01-13 with total page 227 pages. Available in PDF, EPUB and Kindle. Book excerpt: J.P. Dahl: Carl Johan Ballhausen (1926–2010).- J.R. Winkler and H.B. Gray: Electronic Structures of Oxo-Metal Ions.- C.D. Flint: Early Days in Kemisk Laboratorium IV and Later Studies.- J.H. Palmer: Transition Metal Corrole Coordination Chemistry. A Review Focusing on Electronic Structural Studies.- W.C. Trogler: Chemical Sensing with Semiconducting Metal Phthalocyanines.- K.M. Lancaster: Biological Outer-Sphere Coordination.- R.K. Hocking and E.I. Solomon: Ligand Field and Molecular Orbital Theories of Transition Metal X-ray Absorption Edge Transitions.- K.B. Møller and N.E. Henriksen: Time-resolved X-ray diffraction: The dynamics of the chemical bond.
Download or read book Molecular Electronic Structures of Transition Metal Complexes II written by David Michael P. Mingos and published by Springer Science & Business Media. This book was released on 2012-01-11 with total page 247 pages. Available in PDF, EPUB and Kindle. Book excerpt: T. Ziegler: A Chronicle About the Development of Electronic Structure Theories for Transition Metal Complexes.- J. Linderberg: Orbital Models and Electronic Structure Theory.- J.S. and J.E. Avery: Sturmians and Generalized Sturmians in Quantum Theory.- B.T Sutcliffe: Chemistry as a “Manifestation of Quantum Phenomena” and the Born–Oppenheimer Approximation?- A.J. McCaffery: From Ligand Field Theory to Molecular Collision Dynamics: A Common Thread of Angular Momentum.- M. Atanasov, D. Ganyushin, K. Sivalingam and F. Neese: A Modern First-Principles View on Ligand Field Theory Through the Eyes of Correlated Multireference Wavefunctions.- R.S. Berry and B.M. Smirnov: The Phase Rule: Beyond Myopia to Understanding.
Download or read book Electronic Structure and Reactivity of Transition Metal Complexes Incorporating Pro radical Bis phenoxide Ligands written by Ryan Michael Clarke and published by . This book was released on 2018 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt: Transition metal complexes with pro-radical ligands have received considerable research attention due to their interesting electronic structures, photophysical properties, and applications in catalysis. The relative ordering of metal and ligand frontier orbitals in a complex incorporating pro-radical ligands dictates whether oxidation/reduction occurs at the metal centre or at the ligand. Many metalloenzymes couple redox events at multiple metal centres or between metals and pro-radical ligands to facilitate multielectron chemistry. Owing to the simplicity of the active sites, many structural and functional models have been studied. One class of pro-radical ligand that has been investigated extensively are bis-imine bis-phenoxide ligands (i.e. salen) due to their highly modular syntheses. In this thesis, projects related to the synthesis, electronic structure, and reactivity of mono and bimetallic complexes incorporating the salen framework are explored. Chapter 2 presents a systematic investigation of the effects of geometry on the electronic structure of four bis-oxidized bimetallic Ni salen species. The tunability of their intense intervalence charge transfer (IVCT) transitions in the near infrared (NIR) by nearly 400 nm due to exciton coupling in the excited states is described. For the first time, this study demonstrates the applicability of exciton coupling to ligand radical systems absorbing in the NIR region. Chapter 3 investigates the ground-state electronic structure of a bis-oxidized Co dimer. Enhanced metal participation to the singly occupied molecular orbitals results in both high spin Co(III) and Co(II)-L• character in the ground state, and no observable band splitting in the NIR due to exciton coupling. Finally, Chapter 4 describes a series of oxidized nitridomanganese(V) salen complexes with different para ring substituents (R = CF3, tBu, and NMe2), demonstrating that nitride activation is dictated by remote ligand electronics. Upon one-electron oxidation, electron deficient ligands afford a Mn(VI) species and nitride activation, whereas an electron-rich ligand results in ligand based oxidation and resistance to N coupling of the nitrides. This study highlights the alternative reactivity pathways that pro-radical ligands impose on metal complexes and represents a key step in the use of NH3 as a hydrogen storage medium. The results presented herein provide a starting point for further efforts in reactivity with the salen platform.
Download or read book A Theoretical Study of the Electronic Structure of Transition metal Complexes written by James W. Richardson and published by . This book was released on 1956 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Electronic Structure and Properties of Transition Metal Compounds written by Isaac B. Bersuker and published by John Wiley & Sons. This book was released on 2010-12-01 with total page 658 pages. Available in PDF, EPUB and Kindle. Book excerpt: With more than 40% new and revised materials, this second edition offers researchers and students in the field a comprehensive understanding of fundamental molecular properties amidst cutting-edge applications. Including ~70 Example-Boxes and summary notes, questions, exercises, problem sets, and illustrations in each chapter, this publication is also suitable for use as a textbook for advanced undergraduate and graduate students. Novel material is introduced in description of multi-orbital chemical bonding, spectroscopic and magnetic properties, methods of electronic structure calculation, and quantum-classical modeling for organometallic and metallobiochemical systems. This is an excellent reference for chemists, researchers and teachers, and advanced undergraduate and graduate students in inorganic, coordination, and organometallic chemistry.
Download or read book Transition Metals in Coordination Environments written by Ewa Broclawik and published by Springer. This book was released on 2019-03-16 with total page 532 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on the electronic properties of transition metals in coordination environments. These properties are responsible for the unique and intricate activity of transition metal sites in bio- and inorganic catalysis, but also pose challenges for both theoretical and experimental studies. Written by an international group of recognized experts, the book reviews recent advances in computational modeling and discusses their interplay using experiments. It covers a broad range of topics, including advanced computational methods for transition metal systems; spectroscopic, electrochemical and catalytic properties of transition metals in coordination environments; metalloenzymes and biomimetic compounds; and spin-related phenomena. As such, the book offers an invaluable resource for all researchers and postgraduate students interested in both fundamental and application-oriented research in the field of transition metal systems.
Download or read book Spectroscopy and Electronic Structure of Transition Metal Complexes written by Dimitrios A. Pantazis and published by . This book was released on 2019-11-19 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt: The combination of spectroscopy and theory has developed considerably in the past two decades. Computational techniques and theoretical analysis to extract electronic structure information from spectroscopy has become a crucial aspect of modern research in chemistry and materials science. This book provides a comprehensive and up-to-date resource on spectroscopic methods used in transition metal chemistry and explains the relationships between experimental techniques and electronic structure. Chapters cover topics including computational chemistry; ligand field theory; magnetochemistry; and optical, vibrational, NMR and EPR spectroscopy. Edited and written by world experts in the field, this unique volume is valuable to students of all levels and serves as a reference for researchers in physical inorganic chemistry, (bio)inorganic chemistry and spectroscopy.
Download or read book Synthesis and Ligand Enabled Reactivity of Transition Metal Complexes Bearing a Redox Active Bis phenoxy amide Ligand written by Aaron M. Hollas and published by . This book was released on 2016 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: The work described herein focuses on the ability of redox-active ligands to enable multi-electron reactivity at transition metal centers. A parallel theme is the effect of ancillary ligands on controlling and modulating the electronic structure of the redox-active ligand and metal center in addition to ancillary ligand effects as they relate to controlling the primary coordination sphere of the metal. (Abstract shortened by ProQuest.).
Download or read book Electronic Structure of Transition Metal Complexes written by Catherine M. Redfern and published by . This book was released on 1988 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Electronic Structure of Transition Metal Complexes written by Catherine M. Redfern and published by . This book was released on 1988 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Electronic structure and excited state properties of some transition metal complexes having a lowest energy metal to ligand charge transfer state written by Peter C. Servaas and published by . This book was released on 1991 with total page 101 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Theoretical Studies of the Electronic Structure and Bonding in Some Transition Metal Complexes of Vanadium Chromium Iron Nickel and Palladium written by Douglas Jay Gordon and published by . This book was released on 1981 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Molecular Electronic Structures of Transition Metal Complexes written by David Michael Patrick Mingos and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Electronic Structure and Alloy Chemistry of the Transition Elements written by Metallurgical Society of AIME. Institute of Metals Division and published by . This book was released on 1963 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Electronic Structure and Properties of Some Transition Metal Complexes written by Alan Roger Latham and published by . This book was released on 1966 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt:
