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5.111 Principles of Chemical Science, Fall 2005 Transcript – Lecture 28
MIT OpenCourseWare http://ocw.mit.edu 5.111 Principles of Chemical Science, Fall 2005 Please use the following citation format: Sylvia Ceyer and Catherine Drennan, 5.111 Principles of Chemical Science, Fall 2005. (Massachusetts Institute of Technology: MIT OpenCourseWare). http://ocw.mit.edu (accessed MM DD, YYYY). License: Creative Commons Attribution-Noncommercial-Share Alike. Note: Please use the actual date you accessed this material in your citation. For more information about citing these materials or our Terms of Use, visit: http://ocw.mit.edu/terms MIT OpenCourseWare http://ocw.mit.edu 5.111 Principles of Chemical Science, Fall 2005 Transcript – Lecture 28 All right. We have a few more PowerPoint things before I am going to attempt using the board. Again, we are in the transition metal unit. And today we are going to introduce something called crystal field theory. And this is in Chapter 16 in your book. Let me just tell you about two different theories. Again, chemistry is an experimental science. We collect data and then we try to come up with theories that explain the data, so the theories are not sort of 100%. And some are more simple and some are more complicated to try to explain what we observe. And some of these theories, although they are pretty simple approximations of what is really going on, do a pretty good job of explaining the things that we are observing. All right. There are two different kinds of theories that you will hear about with transition metals. You will hear about crystal field theory and ligand field theory. -
Clusters – Contemporary Insight in Structure and Bonding 174 Structure and Bonding
Structure and Bonding 174 Series Editor: D.M.P. Mingos Stefanie Dehnen Editor Clusters – Contemporary Insight in Structure and Bonding 174 Structure and Bonding Series Editor: D.M.P. Mingos, Oxford, United Kingdom Editorial Board: X. Duan, Beijing, China L.H. Gade, Heidelberg, Germany Y. Lu, Urbana, IL, USA F. Neese, Mulheim€ an der Ruhr, Germany J.P. Pariente, Madrid, Spain S. Schneider, Gottingen,€ Germany D. Stalke, Go¨ttingen, Germany Aims and Scope Structure and Bonding is a publication which uniquely bridges the journal and book format. Organized into topical volumes, the series publishes in depth and critical reviews on all topics concerning structure and bonding. With over 50 years of history, the series has developed from covering theoretical methods for simple molecules to more complex systems. Topics addressed in the series now include the design and engineering of molecular solids such as molecular machines, surfaces, two dimensional materials, metal clusters and supramolecular species based either on complementary hydrogen bonding networks or metal coordination centers in metal-organic framework mate- rials (MOFs). Also of interest is the study of reaction coordinates of organometallic transformations and catalytic processes, and the electronic properties of metal ions involved in important biochemical enzymatic reactions. Volumes on physical and spectroscopic techniques used to provide insights into structural and bonding problems, as well as experimental studies associated with the development of bonding models, reactivity pathways and rates of chemical processes are also relevant for the series. Structure and Bonding is able to contribute to the challenges of communicating the enormous amount of data now produced in contemporary research by producing volumes which summarize important developments in selected areas of current interest and provide the conceptual framework necessary to use and interpret mega- databases. -
Perspectives on How Nature Employs the Principles of Organometallic Chemistry in Dihydrogen Activation in Hydrogenases†
4682 Organometallics 2010, 29, 4682–4701 DOI: 10.1021/om100436c Perspectives on How Nature Employs the Principles of Organometallic Chemistry in Dihydrogen Activation in Hydrogenases† John C. Gordon* and Gregory J. Kubas* Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, United States Received May 6, 2010 Relatively recent developments in metalloenzyme and organometallic chemistry have targeted a growing link between these outwardly incongruous fields, giving birth to a merger now popularly termed “bio-organometallic” chemistry. The astonishing discovery of CO and CN ligands bound to dinuclear iron sites in billion-year-old hydrogenase enzymes has led to a new paradigm and triggered an explosion of research on bioinspired chemistry. The article will focus on the impressive array of organometallic chemistry principles that work in concert in the structure and function of H2ases. Molecular H2 is at the forefront of bioinspired energy, and its production and storage are critical for renewable energy systems. Biomimetic inorganic chemistry and photochemistry involving water splitting for H2 production has erupted in the past decade and will also be reflected upon here. I. Introduction be despised and avoided by nature. This view was shattered by the relatively recent discovery, initially spectroscopically2,3 then At the macroscopic level, nature displays dazzling beauty crystallographically,4 of CO and CN ligands bound to dinuclear and surprises on a regular basis. On the molecular level, its iron sites in hydrogenase (H2ase) enzymes that have existed in mystique is even more fascinating to biologists and chemists numerous microorganisms for over a billion years. It is now in all their subfields. -
N-Heterocyclic Carbenes (Nhcs)
Baran Lab N - H e t e r o c y c l i c C a r b e n e s ( N H C s ) K. J. Eastman An Introduction to N-heterocyclic Carbenes: How viable is resonance contributer B? Prior to 1960, a school of thought that carbenes were too reactive to be smaller isolated thwarted widespread efforts to investigate carbene chemistry. base ! N N N N R R R R Perhaps true for the majority of carbenes, this proved to be an inaccurate X- assessment of the N-heterocyclic carbenes. H longer Kirmse, W. Angerw. Chem. Int. Ed. 2004, 43, 1767-1769 In the early 1960's Wanzlick (Angew. Chem. Int. Ed. 1962, 1, 75-80) first investigated the reactivity and stability of N-heterocyclic carbenes. Attractive Features of NHCs as Ligands for transition metal catalysts: Shortly thereafter, Wanzlick (Angew. Chem. Int. Ed. 1968, 7, 141-142) NHCs are electron-rich, neutral "#donor ligands (evidenced by IR frequency of reported the first application of NHCs as ligands for metal complexes. CO/metal/NHC complexes). Surprisingly, the field of of NHCs as ligands in transition metal chemistry Electron donating ability of NHCs span a very narrow range when compared to remained dormant for 23 years. phosphine ligands In 1991, a report by Arduengo and co-workers (J. Am. Chem. Soc. 1991, Electronics can be altered by changing the nature of the azole ring: 113, 361-363) on the extraodinary stability, isolation and storablility of benzimidazole<imidazole<imidazoline (order of electron donating power). crystalline NHC IAd. NHC-metal complex stability: NaH, DMSO, MeOH N N N N + H2 + NaCl NHCs form very strong bonds with the majority of metals (stronger than Cl- phosphines!) H IAd N-heterocyclic carbenes are electronically (orbital overlap) and sterically (Me vs. -
Organometrallic Chemistry
CHE 425: ORGANOMETALLIC CHEMISTRY SOURCE: OPEN ACCESS FROM INTERNET; Striver and Atkins Inorganic Chemistry Lecturer: Prof. O. G. Adeyemi ORGANOMETALLIC CHEMISTRY Definitions: Organometallic compounds are compounds that possess one or more metal-carbon bond. The bond must be “ionic or covalent, localized or delocalized between one or more carbon atoms of an organic group or molecule and a transition, lanthanide, actinide, or main group metal atom.” Organometallic chemistry is often described as a bridge between organic and inorganic chemistry. Organometallic compounds are very important in the chemical industry, as a number of them are used as industrial catalysts and as a route to synthesizing drugs that would not have been possible using purely organic synthetic routes. Coordinative unsaturation is a term used to describe a complex that has one or more open coordination sites where another ligand can be accommodated. Coordinative unsaturation is a very important concept in organotrasition metal chemistry. Hapticity of a ligand is the number of atoms that are directly bonded to the metal centre. Hapticity is denoted with a Greek letter η (eta) and the number of bonds a ligand has with a metal centre is indicated as a superscript, thus η1, η2, η3, ηn for hapticity 1, 2, 3, and n respectively. Bridging ligands are normally preceded by μ, with a subscript to indicate the number of metal centres it bridges, e.g. μ2–CO for a CO that bridges two metal centres. Ambidentate ligands are polydentate ligands that can coordinate to the metal centre through one or more atoms. – – – For example CN can coordinate via C or N; SCN via S or N; NO2 via N or N. -
Bond Distances and Bond Orders in Binuclear Metal Complexes of the First Row Transition Metals Titanium Through Zinc
Metal-Metal (MM) Bond Distances and Bond Orders in Binuclear Metal Complexes of the First Row Transition Metals Titanium Through Zinc Richard H. Duncan Lyngdoh*,a, Henry F. Schaefer III*,b and R. Bruce King*,b a Department of Chemistry, North-Eastern Hill University, Shillong 793022, India B Centre for Computational Quantum Chemistry, University of Georgia, Athens GA 30602 ABSTRACT: This survey of metal-metal (MM) bond distances in binuclear complexes of the first row 3d-block elements reviews experimental and computational research on a wide range of such systems. The metals surveyed are titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, and zinc, representing the only comprehensive presentation of such results to date. Factors impacting MM bond lengths that are discussed here include (a) n+ the formal MM bond order, (b) size of the metal ion present in the bimetallic core (M2) , (c) the metal oxidation state, (d) effects of ligand basicity, coordination mode and number, and (e) steric effects of bulky ligands. Correlations between experimental and computational findings are examined wherever possible, often yielding good agreement for MM bond lengths. The formal bond order provides a key basis for assessing experimental and computationally derived MM bond lengths. The effects of change in the metal upon MM bond length ranges in binuclear complexes suggest trends for single, double, triple, and quadruple MM bonds which are related to the available information on metal atomic radii. It emerges that while specific factors for a limited range of complexes are found to have their expected impact in many cases, the assessment of the net effect of these factors is challenging. -
Cyclopentadienyl Compounds of the First Row Transition Metals And
University of Vermont ScholarWorks @ UVM Graduate College Dissertations and Theses Dissertations and Theses 2017 Cyclopentadienyl Compounds of the First Row Transition Metals and Early Actinides: Novel Main-Group Bond Forming Catalysis and New Metallacycles Justin Kane Pagano University of Vermont Follow this and additional works at: https://scholarworks.uvm.edu/graddis Part of the Chemistry Commons Recommended Citation Pagano, Justin Kane, "Cyclopentadienyl Compounds of the First Row Transition Metals and Early Actinides: Novel Main-Group Bond Forming Catalysis and New Metallacycles" (2017). Graduate College Dissertations and Theses. 700. https://scholarworks.uvm.edu/graddis/700 This Dissertation is brought to you for free and open access by the Dissertations and Theses at ScholarWorks @ UVM. It has been accepted for inclusion in Graduate College Dissertations and Theses by an authorized administrator of ScholarWorks @ UVM. For more information, please contact [email protected]. CYCLOPENTADIENYL COMPOUNDS OF THE FIRST ROW TRANSITION METALS AND EARLY ACTINIDES: NOVEL MAIN-GROUP BOND FORMING CATALYSIS AND NEW METALLACYCLES A Dissertation Presented by Justin Kane Pagano to The Faculty of the Graduate College of The University of Vermont In Partial Fulfilment of the Requirements For the Degree of Doctor of Philosophy Specializing in Chemistry May, 2017 Defense Date: November 29, 2016 Dissertation Examination Committee: Rory Waterman, Ph. D., Advisor John M. Hughes, Ph. D., Chairperson Matthias Brewer, Ph. D. Jaqueline L. Kiplinger, Ph. D. Matthew D. Liptak, Ph. D. Cynthia J. Forehand, Ph. D., Dean of the Graduate College ABSTRACT Cyclopentadienyl first row transition-metal compounds have been well studied 5 since the 1950’s, with the nearly ubiquitous CpFe(CO)2Me (FpMe) (Cp = η -C5H5) being one of the first organometallics to be fully characterized. -
Neutral All Metal Aromatic Half-Sandwich Complexes Between Alkaline Earth and Transition Metals: an Ab-Initio Exploration
Neutral All Metal Aromatic Half-Sandwich Complexes Between Alkaline Earth and Transition Metals: An Ab-initio Exploration Amlan Jyoti Kalita Cotton University Prem Prakash Sahu Cotton University Ritam Raj Borah Gauhati University Shahnaz Sultana Rohman Cotton University Chayanika Kashyap Cotton University Sabnam Swabaka Ullah Cotton University Indrani Baruah Cotton University Lakhya Jyoti Mazumder Cotton University Dimpul Konwar Gachon University Ankur Kanti Guha ( [email protected] ) Cotton University https://orcid.org/0000-0003-4370-8108 Research Article Keywords: Half-sandwich complexes, dual aromaticity, topological analyses Posted Date: May 24th, 2021 DOI: https://doi.org/10.21203/rs.3.rs-505446/v1 License: This work is licensed under a Creative Commons Attribution 4.0 International License. Read Full License Page 1/13 Version of Record: A version of this preprint was published at Structural Chemistry on July 7th, 2021. See the published version at https://doi.org/10.1007/s11224-021-01807-w. Page 2/13 Abstract Sandwich complexes nd their interests among the chemists after the breakthrough discovery of ferrocene. Since then, a number of sandwich and half sandwich complexes were predicted and synthesized. Herein, we have theoretically proposed a series of half-sandwich complexes involving a neutral Be3 ring and transition metal. Quantum chemical calculations have shown that the proposed complexes are quite stable involving high bond dissociation energies. The thermodynamics of their formation is also favorable. The Be3 ring in all cases posses dual aromaticity which has been ascertained based on magnetic as well as topological feature of electron density. Introduction Discovery of the rst sandwich complex (C5H5)2Fe, commonly known as “ferrocene”, drew the attention of the chemistry fraternity in no time [1–3]. -
Chem-601: Structure and Bonding of Molecules and Materials
Chem-601: Structure and Bonding of Molecules and Materials Instructor: Efrain E. Rodriguez [email protected] Office: Chemistry 4101 Office hours: MW 2-3, and by appointment Lectures: Chemistry 0122 MWF, 10 AM – 10:50 AM Grading scheme: 8 problem sets 150 points total Midterm exams (2) 75 points each Final exam 100 points TOTAL 400 points Textbooks: 1) G L. Miessler and D. A. Tarr, Inorganic Chemistry, 4th Ed., Pearson, 2011. 2) R. L. Carter, Molecular Symmetry and Group Theory, Wiley, 1998. Tentative lecture schedule (readings in parentheses): 1.) A survey of inorganic and materials chemistry today 2.) Atomic structure a. Refresher on quantum and hydrogen-like orbitals (IC 2.1 to 2.2.2). b. Multi-electron orbitals, aufbau principle, and periodicity (IC rest of Ch. 2). 3.) Simple bonding models in molecules and solids a. Octet rule, VSPER structures, the valence bond model and resonance (IC Ch 3). b. Ionic bonding, prototype solid structures, Born-Haber cycle to calculate lattice energies (IC 7.1 to 7.2.2 ). 4.) Group theory a. Symmetry elements, point groups, and multiplication tables (MSGT Ch. 1). b. Representations and character tables (MSGT Ch. 2). c. Irreducible representations and correlation tables (MSGT Ch. 3) d. Group theory approach to VB theory and hybrid orbitals (MSGT 4.1 to 4.2) 5.) Molecular orbital theory a. Linear combination of atomic orbitals, homonuclear diatomic molecules (IC 5.1 to 5.2.5) b. Polar and larger molecules (IC rest of Ch. 5). c. Symmetry adapted linear combination (SALC) orbitals (MSGT 4.3 to 4.5). -
A Ladder Polysilane As a Template for Folding Palladium Nanosheets
ARTICLE Received 15 Mar 2013 | Accepted 15 May 2013 | Published 14 Jun 2013 DOI: 10.1038/ncomms3014 A ladder polysilane as a template for folding palladium nanosheets Yusuke Sunada1,2, Ryohei Haige2, Kyohei Otsuka3, Soichiro Kyushin3 & Hideo Nagashima1,2 Although discrete nano-sized compounds consisting of a monolayer sheet of multiple atoms have attracted much attention, monolayer transition metal nanosheets are difficult to access. Here we report a template synthesis of the folding metal nanosheet (2) consisting of 11 palladium atoms by treatment of a ladder polysilane, decaisopropylbicyclo[2.2.0]hexasilane t (1), with Pd(CN Bu)2. Crystallographic analysis reveals that the compound is composed of two monolayer Pd7 sheets sharing three palladium atoms at the junction. Each Pd atom is stabilized by Pd–Si s-bonds, Pd–Pd bonds and coordination of isocyanides. Ligand exchange t of 2 from CN Bu to CN(2,4,6-Me3-C6H2) is accompanied by structural rearrangement, leading to the formation of another folding Pd11 nanosheet (3) consisting of two edge-sharing Pd7 sheets. The shapes of the Pd7 sheets as well as the dihedral angle between the two Pd7 sheets are dependent on the substituent of the isocyanide ligand. 1 Institute for Materials Chemistry and Engineering, Kyushu University and CREST, Japan Science and Technology Agency (JST), Kasuga, Fukuoka 816-8580, Japan. 2 Graduate School of Engineering Sciences, Kyushu University, 6-1 Kasugakoen, Kasuga, Fukuoka 816-8580, Japan. 3 Department of Chemistry and Chemical Biology, Graduate School of Engineering, Gunma University, Kiryu, Gunma 376-8515, Japan. Correspondence and requests for materials should be addressed to H.N. -
Organometallic and Catalysis
ORGANOMETALLIC AND CATALYSIS Dr. Malay Dolai, Assistant Professor, Department of Chemistry, Prabhat Kumar College, Contai, Purba Medinipur-721404, WB, India. 1.Introduction Organometallic chemistry is the study of organometallic compounds, chemical compounds containing at least one chemical bond between a carbon atom of an organic molecule and a metal, including alkaline, alkaline earth, and transition metals, and sometimes broadened to include metalloids like boron, silicon, and tin, as well. Aside from bonds to organyl fragments or molecules, bonds to 'inorganic' carbon, like carbon monoxide (metal carbonyls), cyanide, or carbide, are generally considered to be organometallic as well. Some related compounds such as transition metal hydrides and metal phosphine complexes are often included in discussions of organometallic compounds, though strictly speaking, they are not necessarily organometallic. The related but distinct term "metalorganic compound" refers to metal-containing compounds lacking direct metal-carbon bonds but which contain organic ligands. In 1827, Zeise's salt is the first platinum- olefin complex: K[PtCl3(C2H4)].H2O, the first invented organometallic compound. Organometallic compounds find wide use in commercial reactions, both as homogeneous catalysis and as stoichiometric reagents For instance, organolithium, organomagnesium, and organoaluminium compounds, examples of which are highly basic and highly reducing, are useful stoichiometrically, but also catalyze many polymerization reactions. Almost all processes involving carbon monoxide rely on catalysts, notable examples being described as carbonylations. The production of acetic acid from methanol and carbon monoxide is catalyzed via metal carbonyl complexes in the Monsanto process and Cativa process. Most synthetic aldehydes are produced via hydroformylation. The bulk of the synthetic alcohols, at least those larger than ethanol, are produced by hydrogenation of hydroformylation- derived aldehydes. -
Synthesis and Reactivity of Cyclopentadienyl Based Organometallic Compounds and Their Electrochemical and Biological Properties
Synthesis and reactivity of cyclopentadienyl based organometallic compounds and their electrochemical and biological properties Sasmita Mishra Department of Chemistry National Institute of Technology Rourkela Synthesis and reactivity of cyclopentadienyl based organometallic compounds and their electrochemical and biological properties Dissertation submitted to the National Institute of Technology Rourkela In partial fulfillment of the requirements of the degree of Doctor of Philosophy in Chemistry by Sasmita Mishra (Roll Number: 511CY604) Under the supervision of Prof. Saurav Chatterjee February, 2017 Department of Chemistry National Institute of Technology Rourkela Department of Chemistry National Institute of Technology Rourkela Certificate of Examination Roll Number: 511CY604 Name: Sasmita Mishra Title of Dissertation: ''Synthesis and reactivity of cyclopentadienyl based organometallic compounds and their electrochemical and biological properties We the below signed, after checking the dissertation mentioned above and the official record book(s) of the student, hereby state our approval of the dissertation submitted in partial fulfillment of the requirements of the degree of Doctor of Philosophy in Chemistry at National Institute of Technology Rourkela. We are satisfied with the volume, quality, correctness, and originality of the work. --------------------------- Prof. Saurav Chatterjee Principal Supervisor --------------------------- --------------------------- Prof. A. Sahoo. Prof. G. Hota Member (DSC) Member (DSC) ---------------------------