DOCSLIB.ORG

Uranium Thiocyanate Compounds in Multiple Oxidation States Stefano

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Uranium Thiocyanate Compounds in Multiple Oxidation States Stefano Uranium Thiocyanate Compounds in Multiple Oxidation States A thesis presented to the University of Dublin, Trinity College for the degree of Doctor of Philosophy in Chemistry by Stefano Nuzzo Under the supervision of Prof. Robert J. Baker School of Chemistry Trinity College Dublin 2019 Declaration I hereby declare that this thesis has not been submitted as an exercise for a degree at this or any other university and it is entirely my own work. I agree to deposit this thesis in the University’s open access institutional or allow the library to do so on my behalf, subject to Irish Copyright Legislation and Trinity College Library conditions of use and acknowledgement. … ………. Stefano Nuzzo II Summary In this thesis a series of high symmetry uranium(IV) and thorium(IV) thiocyanate n complexes of the type A4[An(NCS)8] (An = Th, U; A = Cs, Me4N, Et4N, Pr4N) have been structurally and spectroscopically characterized. It was shown that the size and shape of the counter cation determine the coordination symmetry around the actinide ion. Interestingly, this effect proved to have a significant influence on the magnetic properties 4− of the [U(NCS)8] ion, as revealed by SQUID and specific heat capacity measurements. Inelastic neutron scattering and far-infrared spectroscopic measurements have been performed on the uranium compounds to examine the corresponding low-lying energy level electronic structures, while a computational approach using the CONDON framework has been used to quantify these energy states. Overall, the experimental and computational data suggest that the energy gap between the ground and the first excited state varies considerably so that for A = Et4N a magnetic singlet ground state is predicted; however, a distortion of the coordination geometry from cubic toward square antiprismatic reduce this energy gap such that a magnetic triplet ground state is observable for A = Cs at low temperatures. This represents the first example of a triplet electronic ground state for a uranium(IV) compound; thus, this study underlines the importance of the coordination geometry to understand the magnetic properties of uranium(IV) compounds. Moreover, a spectroscopic and magnetic analysis has been carried out also on two uranium(IV) selenocyanate complexes of the type A4[U(NCS)8] n (A = Et4N, Pr4N); however, no significant differences in the electronic structure have been observed with respect to the equivalents thiocyanate compounds. 4− The reactivity of the [U(NCS)8] ion has also been examined in organic media of diverse polarity and with several different counter cations. From oxidation processes of Cs4[U(NCS)8], two mixed-valent uranium compounds have been isolated and structurally characterized. A spectroscopic, magnetic and computational analysis has been performed to unequivocally delineate the electronic configuration of these systems; a photophysical study also revealed the presence of both uranium(IV) and uranyl(VI) together in one compound. A reaction between Na4[U(NCS)8] and [Co(bipy)3][PF6]2 led to the formation of a compound of formula [Co(bipy)3][U(NCS)8] for which spectroscopic and magnetic properties suggest the presence of a pentavalent uranium(V) ion, but the mechanism of the synthesis is not clear. The synthesis of homoleptic uranium(III) thiocyanate complexes, from reductions of uranium(IV) precursors, have also been attempted, but III 4− without success; however, a spectroelectrochemistry study on [U(NCS)8] has shown that the addition of one electron to the metal ion causes the dissociation of all the π-donor [NCS]− ligands and decomposition of the sample. Theoretical calculations have also revealed an enhanced ionicity for the U(III)–N compared to the U(IV)–N bond, which can explain the observed decomposition. A series of uranyl(VI) thiocyanate [NCS]− and selenocyanate [NCSe]− complexes, of the n type [R4N]3[UO2(NCS)5 (R4 = Bu4, Me3Bz, Et3Bz), [Ph4P][UO2(NCS)3(NO3)] and n [R4N]3[UO2(NCSe)5] (R4 = Me4, Pr4, Et3Bz) have also been described. X-ray crystallography, NMR, vibrational and photoluminescence spectroscopy and theoretical methods have been used to explore the non-covalent interactions present in the structures of these compounds, namely: charge assisted C—H…O=U and C—H…S(e) hydrogen bonding, and Se…Se or S…S chalcogenide interactions. Chalcogenide interactions have been observed in some of the structures and were more prevalent in the [NCSe]− series than in the [NCS]−. Charge assisted hydrogen bonding to the –yl oxygens were also noticed, but they were weak and not able to strongly influence the spectroscopic properties of the uranyl moiety. Finally, a detailed structural, spectroscopic and theoretical study on a series of 10-[(4- halo-2,6-diisopropylphenyl)imino]phenanthren-9-ones and derivatives of the phenanthrene-9,10-dione ligand has been discussed. Particular attention has been reserved on the analysis of the supramolecular non-covalent interactions exhibited by the structures of these molecules, such as “π–π stacking”, C–H…π, C–X lone pair…π, C– X…H–C and C–X…X–C. DFT and AIM analysis have also been used to compare the strength of these interactions. It was found that the lone pair···π interactions were the dominant halogen type interactions and a computational study showed that these were stabilizing and of the same order of magnitude as interactions from lone pairs deriving from oxygen or nitrogen donor atoms. However, among all the interactions, the most important one appeared to be a weak hydrogen bond between the C–H of a phenanthrene and the carbonyl oxygen. These ligands were also reduced by reaction with potassium metal to form iminoalkoxy semiquinone radical anions. A spectroscopic analysis confirmed the formation of radical species, but these were isolated as powders only and it was not possible to grow single crystals. Reactions between UCl4, as source of U(IV), and these radicals have been also attempted. However, the desired compounds, that could potentially show magnetic coupling interactions between the radical and the uranium metal, have not been isolated. IV Acknowledgement Firstly, I would like to express my sincere gratitude to my supervisor Prof. Robert James Baker for his continuous support during my PhD study and related research, for his enormous patience with my mistakes. His guidance helped me in all the time of research and writing of this thesis. Thank you very, very much. Besides my supervisor, I would like to thank Dr. Brendan Twamley for his enormous contribute throughout my project; thank you for all the crystal structures that you refined for me, for your help in the lab and your encouragements. I also would like to thank Dr. John O’ Brien for being the “NMR god” and, of course, Dr. Manuel Ruether for “simply” being the king of the spectroscopic instruments; thank you both for being always present. Obviously, I also want to thank all the members of the stuff in the School of Chemistry of Trinity College. My sincere thanks go also to Professor Michael Probert from University of New Castle for welcoming me in his group even if for a short period, for diffracting two of my single crystals at 4 K and for explaining me how a single crystal can be diffracted at different pressures. Moreover, I would like to express my gratitude to Dr. Marco Evangelisti and Dr. Giulia Lorusso (from University of Saragoza), for measuring the magnetic properties of my samples, to Dr. Duc Lee and Dr. Helen C. Walker (from the ISIS facility) for the INS experiments, to Silvia Capelli (from ISIS Neutron and Muon Facility) for the single- crystal neutron diffraction analysis, to Dr. Milan Orlita (from Grenoble) for the FIR measurements, to Dr. James a. Platts (from Cardiff University) and Dr. A. Kerridge (from Lancaster university) and Dr. P. Kӧgerel (from Aachen University) for the computational calculations. I thank my fellow labmates, in particular Dr. Harrison Omorodin and Samuel Edwards, for their help in the lab and for all the fun we have had in the last four years. A big thank goes in particular to Dr. Saptarshi Biswas for simply being Saptarshi and for his suggestions and helps during difficult experiments. I wish to thank all my friends in Dublin, in particular Luca and Imma, and the members of the Colavita group: Khairul, Adam, Federico, Johana, James, Ronan, Guido, Alessandro, Carlota and Letizia for being a very nice office-mates. Last but not the least, I want to thank my family: my parents, my brothers and my sister for their support throughout my project and during the writing of this thesis. V Table of Contents List of Appendices List of Figures List of Tables List of Schemes List of Abbreviations Chapter 1: Introduction 1.1 Overview 2 1.2 Actinides and Nuclear Energy 3 1.3 Chemical Characteristics of Actinides 8 1.3.1 Spin-Orbit Coupling 15 1.4 Photophysical Properties of Actinides 16 1.4.1 Structures and Photophysical Properties of Uranyl(VI) Ion 18 1.4.2 Photophysical Properties of Uranyl(V) Ion 22 1.4.3 Photophysical Properties of Actinide(IV) Ions 23 1.4.4 Photophysical Properties of Actinide(III) Ions 27 1.5 Magnetic Properties of Actinide Ions 28 1.5.1 Magnetic Susceptibility of Uranium Ions 28 1.6 The thiocyanate Ion 32 1.7 Aims of the Project 33 1.7 References 34 Chapter 2: Structural and spectroscopic investigation of A4[U(NCE)8] (A = Cs, n Me4N, Et4N, Pr4N; E = S, Se) 2.1 Introduction 45 2.2 Systematic Structural and Spectroscopic Study of A4[An(NCS)8] (An = Th, U; A n = Cs, Me4N, Et4N, Pr4N) 50 2.2.1 Synthesis and Structural Characterization 50 2.2.2 Structural Distortion
Load more

Recommended publications
  • Separation of Radioactive Elements from Rare Earth Element-Bearing Minerals
    metals Review Separation of Radioactive Elements from Rare Earth Element-Bearing Minerals Adrián Carrillo García 1, Mohammad Latifi 1,2, Ahmadreza Amini 1 and Jamal Chaouki 1,* 1 Process Development Advanced Research Lab (PEARL), Chemical Engineering Department, Ecole Polytechnique de Montreal, C.P. 6079, Succ. Centre-ville, Montreal, QC H3C 3A7, Canada; [email protected] (A.C.G.); mohammad.latifi@polymtl.ca (M.L.); [email protected] (A.A.) 2 NeoCtech Corp., Montreal, QC H3G 2N7, Canada * Correspondence: [email protected] Received: 8 October 2020; Accepted: 13 November 2020; Published: 17 November 2020 Abstract: Rare earth elements (REE), originally found in various low-grade deposits in the form of different minerals, are associated with gangues that have similar physicochemical properties. However, the production of REE is attractive due to their numerous applications in advanced materials and new technologies. The presence of the radioactive elements, thorium and uranium, in the REE deposits, is a production challenge. Their separation is crucial to gaining a product with minimum radioactivity in the downstream processes, and to mitigate the environmental and safety issues. In the present study, different techniques for separation of the radioactive elements from REE are reviewed, including leaching, precipitation, solvent extraction, and ion chromatography. In addition, the waste management of the separated radioactive elements is discussed with a particular conclusion that such a waste stream can be
    [Show full text]
  • United States Patent Office 2,988,421
    United States Patent Office Patented June2,988,421 13, 196 heavailaaaar 1 2 contain more than 200 gms. alkali metal and chloride ions 2,988,421 per litre. The following tables show the loss of thorium PROCESS FOR THE SEPARATION OF THORUM and lanthanons under various conditions in the presence WilliamANDRARE Palmer Kemp, EARTHS Shenfield, FROM and MONAZTE James Johnston, 5 of sodium and potassium chloride. Hainault, England, assignors to Thorium Limited, Lon don, England, a corporation of Great Britain NaCl, ThO Ln2O No Drawing. Filed Aug. 20, 1957, Ser. No. 679,126 Acidity gm.fl. loss, loss, Claim priority, application Great Britain Aug. 24, 1956 gm.fl. gm.fl. 9 Claims. (C. 23-145) -ror-rm-m-m------- 10 : 122 This invention relates to a process for separating thori- 4.5 8: um and lanthanon salts from other materials present in : g monazite. The invention is particularly useful in that it 55 i. provides a process for separating salts of thorium and the : 8. lanthanons from phosphate and impurities present in 1655 400 6.65 ground mineral monazite. The term lanthanon in this specification includes the elements with atomic numbers KC ThO Ln2O from 57-71; this group is also known as the rare earth Acidity fi. is is elements. gm.fl. gm.fl. Monazite sand is a mineral phosphate containing thori- .am-m-m-m-m-m-m-wn um and the lanthanon phosphates to the extent of about 38 o' 95-98% by weight. Another source is ground mineral 300 0.005 1.0 monazite which is far less pure than monazite sand and contains only about 75% of the thorium and lanthanon In a preferred form of the process the filtered extract phosphates.
    [Show full text]
  • Thorium–Ligand Multiple Bonds Via Reductive Deprotection of a Trityl Group† Cite This: Chem
    Chemical Science View Article Online EDGE ARTICLE View Journal | View Issue Thorium–ligand multiple bonds via reductive deprotection of a trityl group† Cite this: Chem. Sci.,2015,6, 3891 Danil E. Smiles,a Guang Wu,a Nikolas Kaltsoyannis*b and Trevor W. Hayton*a Reaction of [Th(I)(NR2)3](R¼ SiMe3)(2) with KECPh3 (E ¼ O, S) affords the thorium chalcogenates, [Th(ECPh3)(NR2)3](3,E¼ O; 4,E¼ S), in moderate yields. Reductive deprotection of the trityl group from 3 and 4 by reaction with KC8, in the presence of 18-crown-6, affords the thorium oxo complex, [K(18- Received 7th April 2015 crown-6)][Th(O)(NR ) ](6), and the thorium sulphide complex, [K(18-crown-6)][Th(S)(NR ) ](7), Accepted 30th April 2015 2 3 2 3 respectively. The natural bond orbital and quantum theory of atoms-in-molecules approaches are DOI: 10.1039/c5sc01248a employed to explore the metal–ligand bonding in 6 and 7 and their uranium analogues, and in particular www.rsc.org/chemicalscience the relative roles of the actinide 5f and 6d orbitals. Introduction be rationalized by the higher energy of the thorium 5f orbitals, Creative Commons Attribution-NonCommercial 3.0 Unported Licence. relative to uranium, which likely weakens metal–ligand The study of actinide–ligand multiple bonds has intensied in p-bonding.50 However, this hypothesis requires further veri- recent years due to the need to understand the extent of both f- cation, highlighting the need for new complexes that feature orbital participation and covalency in actinide–ligand thorium–ligand multiple bonds.
    [Show full text]
  • High Coordination Number Compounds of Thorium Borohydride, and of Calcium and Strontium , Dimethylaminodiboranates
    HIGH COORDINATION NUMBER COMPOUNDS OF THORIUM BOROHYDRIDE, AND OF CALCIUM AND STRONTIUM , -DIMETHYLAMINODIBORANATES BY ANDREW CLIFFORD DUNBAR DISSERTATION Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Chemistry in the Graduate College of the University of Illinois at Urbana-Champaign, 2011 Urbana, Illinois Doctoral Committee: Professor Gregory S. Girolami, Chair Professor Andrew A. Gewirth Professor Ralph G. Nuzzo Professor Thomas B. Rauchfuss ABSTRACT We have determined the crystal structure of Th(BH 4)4 and confirmed that it is - isomorphous with the tetragonal form of its uranium analogue. Of the four BH 4 groups per formula unit, two are terminal and are bound to thorium in a tridentate κ 3 fashion, and - 2 2 the other two BH 4 groups bridge between neighboring Th centers in a bis(bidentate) κ ,κ - fashion. In this arrangement each Th center is bound to six BH 4 groups which form a total of 14 Th-H bonds (2 × 3 + 4 × 2). If one ignores the hydrogen atoms, the six boron atoms about each Th center describe a distorted octahedral arrangement, in which the two 3 - terminal κ -BH 4 groups are mutually cis . The 14 hydrogen atoms surrounding the central thorium atom do not describe a simple regular coordination polyhedron, although it is possible to view the arrangement as a highly distorted bicapped hexagonal antiprism. The metal centers are linked into a three-dimensional polymer that consists of interconnected helical chains wound about fourfold screw axes. The most interesting result is that the Th and U complexes show some systematic differences in bond distances and angles, which is tentatively attributed either to the different f-electron configurations of these two ions (f 0 vs f 2) or to the lower energies of the f-orbitals on uranium.
    [Show full text]
  • Ab Initio Study of Elastic and Electronic Properties of Cubic Thorium Pnictides Thpn and Th3pn4 (Pn = P, As, and Sb)
    Accepted in Solid State Sciences Ab initio study of elastic and electronic properties of cubic thorium pnictides ThPn and Th3Pn4 (Pn = P, As, and Sb) I.R. Shein, * A.L. Ivanovskii Institute of Solid State Chemistry, Ural Branch of the Russian Academy of Sciences, 620990, Ekaterinburg, Russia A B S T R A C T Full-potential linearized augmented plane-wave method with the generalized gradient approximation for the exchange-correlation potential was applied for comparative study of elastic and electronic properties of six cubic thorium pnictides ThPn and Th3Pn4, where Pn = P, As, and Sb. Optimized lattice parameters, theoretical density, independent elastic constants (Cij), bulk moduli (B), shear moduli (G), Young’s moduli (Y), and Poisson’s ratio (ν) were obtained for the first time and analyzed in comparison with available theoretical and experimental data. The electronic band structures, total and partial densities of states for all ThPn and Th3Pn4 phases were examined systematically. Moreover, the inter-atomic bonding pictures in thorium pnictides, as well as the relative stability of ThPn versus Th3Pn4 phases were discussed. Keywords: Cubic thorium pnictides ThPn, Th3Pn4; Electronic, Elastic Properties; Chemical bonding; ab initio calculations ---------------- * Corresponding author: E-mail address: [email protected] (I.R. Shein) 1 1. Introduction Binary compounds formed by thorium with sp elements have attracted much attention owing to their unique physical and chemical properties making them interesting from the fundamental point of view, as well as for a variety of technical applications, for example as alternative fertile materials to be used in nuclear breeder systems etc., see [1-5].
    [Show full text]
  • Preparation of Highly Pure Thorium Nitrate Via Thorium Sulfate And
    L Journal of Alloys and Compounds 323±324 (2001) 53±56 www.elsevier.com/locate/jallcom Preparation of highly pure thorium nitrate via thorium sulfate and thorium peroxide Alcõdio AbraoÄ * , Antonio Alves de Freitas, Fatima Maria Sequeira de Carvalho Instituto de Pesquisas Energeticas e Nucleares (IPEN), ComissaoÄ Nacional de Energia Nuclear (CNEN), Travessa R, 400 Cidade Universitaria -USP, CEP 05508-900, SaoÄ Paulo, Brazil Abstract A simple alternative and selective method has been proposed for the preparation of thorium nitrate using as raw material a hydrated crystalline technical grade thorium sulfate. This salt was produced industrially [1] from the alkaline chemical processing of monazite sand in S. Paulo. From a crude thorium hydroxide as the raw material containing uranium and rare earth elements was prepared a technical grade thorium sulfate [Th(SO42 ) .9H 2 O]. A typical analysis of this salt had shown the following composition: ThO223 47±53%, R O (rare earth oxides) 0.5±0.9%, and UO3 0.01% and minor amounts of iron, titanium, phosphorus, and silicon oxides. The thorium sulfate is dissolved into water and the thorium peroxide is precipitated from acidic medium by addition of hydrogen peroxide. The thorium peroxide is ®ltered, washed and ®nally dissolved with nitric acid. Samples of the thorium peroxide were dried and ®red to ThO2 and aliquot of the thorium nitrate solution was evaporated to dryness and calcined to obtain the ThO22 . Both ThO have high purity (.99.5%). The content of total rare earth elements is very low (0.23% as oxide). Uranium was not detected. The great majority of the RE is precipitated and recovered from the ®ltrate by oxalic acid.
    [Show full text]
  • A Computer-Assisted Evaluation of the Thermochemical Data of the Compounds of Thorium
    & TECH NATX INST. OF 5TAND NIST REFERENCE NBSIR 77-1300 A Computer-Assisted Evaluation of the Thermochemical Data of the Compounds of Thorium D. D. Wagman, R. H. Schumm and V. B. Parker Physical Chemistry Division Institute for Materials Research National Bureau of Standards Washington, D.C. 20234 August 1 977 r> ^rati for Qd, 3nal Atomic Energy Agency f Standard Reference Data, NBS /f77 NBSIR 77-1300 A COMPUTER-ASSISTED EVALUATION OF THE THERMOCHEMICAL DATA OF THE COMPOUNDS OF THORIUM D. D. Wagman, R. H. Schumm and V. B. Parker Physical Chemistry Division Institute for Materials Research National Bureau of Standards Washington, D.C. 20234 August 1977 Prepared for International Atomic Energy Agency and Office of Standard Reference Data, NBS U.S. DEPARTMENT OF COMMERCE, Juanita M. Kreps, Secretary Dr. Sidney Harman, Under Secretary Jordan J. Baruch, Assistant Secretary for Science and Technology NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Acting Director TABLE OF CONTENTS I. General Description 1. Introduction 2 2. Explanation of the Contents of Tables 3 3. Unit of Energy and Fundamental Constants 8 4. Internal Consistency of the Tables 9 5. Arrangement of the Tables 11 II. Tables of Values for AHf% A3f° and S° at 298.15 K for the Compounds of Thorium and the Reaction Catalog III. Bibliography IV. Appendix: Thermal Functions for Thorium Compounds A-1 Th(c,l) A-6 Th(g) ' A-7 ThO(g) A-8 ThO^Cc) A-9 Th02(g) A-10 ThF(g) A-11 ThF^Cg) A-12 ThF^(g) A-13 ThF^(c,l) A- 14 ThF^(g) A-15 ThCl(g) A- 16 ThCl2(g) A-17 ThCl^Cg) A-18 ThCl^ (c,l) A-19 ThCl^(g) A-20 ThBr(g) A-21 ThBr2(g) A-22 ThBr^Cg) A-23 ThBr^(c,l) k-lu, ThBr^(g) A-25 Thl(g) ' \ A-26 Thl^Cg) A-27 ThIgCg) A-28 Thl^(c,l) A-29 A Computer-Assisted Evaluation of the Thermochemica 1 Data of the Compounds of Thorium by D.
    [Show full text]
  • Alkali Metal Actinide Complex Halides : Thermochemical and Structural Considerations J
    Alkali metal actinide complex halides : thermochemical and structural considerations J. Fuger To cite this version: J. Fuger. Alkali metal actinide complex halides : thermochemical and structural considerations. Journal de Physique Colloques, 1979, 40 (C4), pp.C4-207-C4-213. 10.1051/jphyscol:1979465. jpa- 00218861 HAL Id: jpa-00218861 https://hal.archives-ouvertes.fr/jpa-00218861 Submitted on 1 Jan 1979 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. JOURNAL DE PHYSIQUE Colloque C4, supplément au n° 4, Tome 40, avril 1979, page C4-207 Alkali metal actinide complex halides: thermochemical and structural considerations J. Fuger Institute of Radiochemistry, University of Liege, Sart Tilman, B-4000 Liege, Belgium Résumé. — L'auteur passe en revue l'état actuel de nos connaissances dans le domaine de la thermodynamique des complexes halogènes d'actinides avec les ions alcalins, en portant une attention toute spéciale aux dérivés chlorés et bromes. Lorsque les données thermodynamiques et structurales sont accessibles, il tente de déduire l'évolution de l'énergie de la liaison actinide-halogène au sein d'une série de composés isomorphes ou analogues. Enfin, la variation énergétique au cours de la formation du complexe halogène à partir des halogénures binaires d'actinides et de métaux alcalins est prise pour base en vue de prévoir la stabilité de composés nouveaux, spécialement ceux pour lesquels l'halogénure binaire d'actinide n'a pas été préparé ou est de faible stabilité.
    [Show full text]
  • Selected Values of Chemical Thermodynamic Properties [Part 8]
    STAND 4 TEtH NATL INST. OF EFERENCE »"" "-r^JL -SOWS « J # W ^ 4t> * 11. % 00 NBS TECHNICAL NOTE 270"8 ^ <Vau of U.S. DEPARTMENT OF COMMERCE/National Bureau of Standards Selected Values of Chemical Thermodynamic Properties Compounds of Uranium, Protactinium, Thorium, Actinium, and the Alkali Metals -QC- lOu No. 270-8 1931 NATIONAL BUREAU OF STANDARDS The National Bureau of Standards' was established by an act ot Congress on March 3, 1901. The Bureau's overall goal is to strengthen and advance the Nation's science and technology and facilitate their effective application for public benefit. To this end, the Bureau conducts research provides: ( ) and I a basis for the Nation's physical measurement system, (2) scientilic and technological services for industry and government, (3) a technical basis tor equity in trade, and (4) technical services to promote public safety. The Bureau's technical work is per- formed by the National Measurement Laboratory, the National Engineering Laboratory, and the Institute for Computer Sciences and Technology. THE NATIONAL MEASUREMENT LABORATORY provides the national system ol physical and chemical and materials measurement; coordinates the system with measurement systems of other nations and furnishes essential services leading to accurate and uniform physical and chemical measurement throughout the Nation's scientilic community, industry, and commerce; conducts materials research leading to improved methods ol measurement, standards, and data on the properties of materials needed by industry, commerce, educational institutions, and Government; provides advisory and research services to other Government agencies; develops, produces, and distributes Standard Relerence Materials; and provides calibration services. The Laboratory consists ol the lollowmg centers: Absolute Physical Quantities — Radiation Research — Thermodynamics and Molecular Science — Analytical Chemistry — Materials Science.
    [Show full text]
  • ©2019 Marissa Ringgold ALL RIGHTS RESERVED
    ©2019 Marissa Ringgold ALL RIGHTS RESERVED ACTINIDE CHALCOGENIDO AND CHALCOGENOLATE COMPOUNDS By MARISSA RINGGOLD A dissertation submitted to the School of Graduate Studies Rutgers, the State University of New Jersey In partial fulfillment of the requirements for the degree of Doctor of Philosophy Graduate Program in Chemistry Written under the direction of John G. Brennan And approved by __________________________ __________________________ __________________________ __________________________ New Brunswick, New Jersey January, 2019 ABSTRACT OF THE DISSERTATION Actinide Chalcogenido and Chalcogenolate Compounds By MARISSA RINGGOLD Disseration Director: John G. Brennan Actinide chemistry, specifically thorium and uranium chalcogenolate and chalcogenido complexes are relatively unexplored. Traditionally in literature they contain sterically hindered environments or are synthesized under aqueous conditions. However, it has been discovered that thorium metal reductively inserts into the E-E bond of REER (R= Ph, C6F5; E = S, Se) to from stable chalcogenolate compounds whose size is determined by the identity of the neutral donor ligand or additional chalcogen in air-free, water-free conditions without the use of large bulky ligands. Thorium cubanes (py)8Th4(μ3-E′)4(μ2-EPh)4(η-EPh)4 (E, E′ = S, Se) were prepared from ligand-based redox reactions of elemental E′ with Th(EPh)4. Products with all four possible E/E′ combinations (E,E′ = S,S; Se,Se; S,Se; Se,S) were isolated and structurally characterized, ligand exchange reactions were explored, and the heterochalcogen compounds (py)8Th4(μ3-S)4(μ2-SePh)4(η-SePh)4 and (py)8Th4(μ3- Se)4(μ2-SPh)4(η-SPh)4 were heated to deliver solid solutions of ThSxSe2−x.
    [Show full text]
  • Actinide Research Quarterly
    Targeted Radiation Therapy Seaborg postdocs developing actinide isotopes for cancer treatments Actinide Research Quarterly Preface In this quarter we continue from the previous issue and present research from another seven recent Seaborg postdoctoral fellows, many of whom have continued their work at Los Alamos National Laboratory (LANL) as scientists. Tis issue focuses on the chemistry of actinide elements relevant to a wide range of challenges, in particular: the separation of nuclear waste, the application of radionuclides in cancer treatments, and the aging of plutonium in the nation’s stockpile. One of the great challenges in actinide chemistry is understanding and predicting bonding in actinide molecules, which could pave the way for developing nuclear waste separation systems. Su (p11) has tackled these problems using advanced computational techniques to understand the nature of chemical bonding in Am3+ and Eu3+ salts, supported by experimental data, providing direct evidence for the frst time to explain behavior originally observed by our institute’s namesake Seaborg and his co-workers over 60 years ago. Te synthesis of the frst Np imido complex—an analog of the well-known neptunyl ion—is described by Brown (p17), a milestone achievement that also opens doors for theoretical studies which can improve our understanding of actinide bonding. Te coordination and catalytic chemistry of T and U has been explored by Browne (p23) and Erickson (p27), who used similar organo- metallic platforms to investigate high-nitrogen content molecules as nuclear fuel precursors and hydrogen-generating catalytic cycles, respectively. Te surface of metallic Pu is highly reactive and dynamic, which creates problems when trying to predict how the material will behave, especially in long-term storage (e.g., in the nation’s stockpile).
    [Show full text]
  • Toxicological Profile for Thorium
    f Toxicological Profile for Thorium September 2019 ***DRAFT – DO NOT CITE OR QUOTE – August 29, 2019*** Version 4.0 THORIUM ii DISCLAIMER Use of trade names is for identification only and does not imply endorsement by the Agency for Toxic Substances and Disease Registry, the Public Health Service, or the U.S. Department of Health and Human Services. THORIUM iii FOREWORD This toxicological profile is prepared in accordance with guidelines* developed by the Agency for Toxic Substances and Disease Registry (ATSDR) and the Environmental Protection Agency (EPA). The original guidelines were published in the Federal Register on April 17, 1987. Each profile will be revised and republished as necessary. The ATSDR toxicological profile succinctly characterizes the toxicologic and adverse health effects information for these toxic substances described therein. Each peer-reviewed profile identifies and reviews the key literature that describes a substance's toxicologic properties. Other pertinent literature is also presented, but is described in less detail than the key studies. The profile is not intended to be an exhaustive document; however, more comprehensive sources of specialty information are referenced. The focus of the profiles is on health and toxicologic information; therefore, each toxicological profile begins with a relevance to public health discussion which would allow a public health professional to make a real-time determination of whether the presence of a particular substance in the environment poses a potential threat to human health. The adequacy of information to determine a substance's health effects is described in a health effects summary. Data needs that are of significance to the protection of public health are identified by ATSDR.
    [Show full text]