DOCSLIB.ORG

LANTHANIDE CHELATES of FLUORINATED A-Oiketones

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
LANTHANIDE CHELATES of FLUORINATED A-Oiketones LANTHANIDE CHELATES OF FLUORINATED a-oIKETONES A thesis submitted to the Faculty of Science in candidacy for the degree of Master of Science by Andrew McPherson Hamer, BSc (Melb. J Supervisor: Professor Stanley E. Livingstone School of Chemistry, The University of New South Wales ~.arch 1984 To my parents It is hereby declared that this thesis has not been submitted, in part or in full, to any other University or Institution for any degree whatsoever. (Andrew M. Hamer) TABLE OF CONTENTS Page No. ABSTRACT V ACK..~OWLEDGEMENTS vi INTRODUCTION 1 PART ONE PREPARATION OF THE LANTHANIDE CHELATES I. Preparation of Fluorinated B-Diketone Ligands 4 II. Preparation and Analyses of Lanthanide Chelates 7 III. Determination of Associated Waters 8 IV. Experimental 15 PART TWO CRYSTAL STRUCTURE OF DIAQUOTRIS(4,4,4-TRIFLUORO­ l-(3'-METHYLPHENYL)-l,3-BUTANEDIONATO)ERBIUM(III) HYDRATE I. Background •.• 18 II. Experimental 21 III. Results and Discussion 25 IV. Programs Used 35 PART THREE VISIBLE SPECTRA OF THE LANTHANIDE CHELATES I. Background ... 37 II. Results and Discussion 39 III. Experimental 69 ,... , , PART FOUR MAGNETIC PROPERTIES OF THE LANTHANIDE CHELATES Page No. I. Background 70 II. Results and Discussion 72 III. Experimental ••• 95 PART FIVE MASS SPECTRA OF THE LANTHANIDE CHELATES I. Background 105 II. Results and Discussion 110 III. Experimental ••. 136 APPENDIX A. Detailed Magnetic Data .•• 137 APPENDIX B. Detailed Mass Spectra 143 APPENDIX C. Atomic Positions and Thermal Parameters of Crystal Structure .. 160 PUBLICATIONS .•• 162 GLOSSARY. Conventions of Mass Spectrometric Notation 163 ABBREVIATIONS 164 REFERENCES 165 iv ABSTRACT Seventy lanthanide complexes of S-diketones have been prepared under carefully controlled conditions. They have been characterised by carbon, hydrogen, and metal analyses. The crystal structure of diaquotris(4,4,4-trifluoro-l-(3'-methyl­ phenyl)-1,3-butanedionato)erbium(III) hydrate was determined. Visible spectra were obtained for most complexes exhibiting -1 absorptions in the range 13000 to 30000 cm The main features observed were: 1. The visible spectra change minimally with chelation. 2. Hypersensitive absorptions were found for complexes of neodymium, holmium and erbium. The variation of the magnetic properties of selected complexes with temperature was observed. All except samarium and europium gave a Curie- Weiss dependence, and all conformed with previous experimental results for lanthanide compounds. Mass spectra were obtained for all the complexes. The most interesting features were: 1. All the lanthanide chelates gave essentially similar mass spectra. 2. Fluorine migration to the metal occurred with all the lanthanide complexes. 3. Valency change from 3 to 2 occurred with samarium (4£5), europium (4£6), thulium (4£12) and ytterbium (4£13). 4. Valency change from 3 to 4 occurred with cerium (4f1), but not with terbium (4£8). V ACKNOWLEDGEMENTS The author gratefully acknowledges the assistance of the following people: Professor S.E. Livingstone, for the opportunity to undertake the degree, his guidance, understanding, and supervision in preparing this tbesis. Mr. A.T. Baker, for much assistance in the solution and refinement of the crystal structure, his discussion on all areas of the thesis, and his support in the laboratory. Mr. D.C. Craig for the collection of the X-ray diffraction data. Dr. J.J. Brophy for persisting with the numerous mass spectra that he obtained. Dr. H.P. Pham, for the many microanalyses. Miss N.J. Ferguson, Mr. M. Antolovich, and all other members of the inorganic research laboratory for making the time enjoyable as well as rewarding. Mrs. G. Ferris and Mrs. N. Ravey for typing this thesis. vi INTRODUCTION With the first complexes being prepared in 1887, complexes of S-diketones are amongst the most widely studied coordination compounds. The capacity of the S-diketones to form inner coordination compounds with a large variety of metals has provided inorganic chemists with what were rare examples of electro-positive metal ions in combinations displaying characteristics of covalent compounds, i.e., solubility in organic solvents and volatility. These characteristics have been exploited in solvent extraction and gas-liquid chromatographic techniques. Metal complexes of B-diketones are also used as contact shift reagents for better resolution of nuclear magnetic resonance spectra of a variety of complex organic molecules, in laser technology and in the polymer industry. S-Diketones, of which a large variety may be synthesised by Claisen condensation, are capable of keto-enol tautomerism. The hydrogen atom of the CH2 group is activated by the adjacent C=O groups and a conjugated system can arise by prototropic shift. The proportion of the enol tautomers generally increases when there is an electron withdrawing group such as an aromatic ring or fluorinated substituent is present in the ligand. 60 •72 The enolic hydrogen atom of the ligand can be replaced by a metal cation to produce a six membered chelate ring. The lanthanides (or rare earths) are the fourteen elements that follow lanthanum in the periodic table and in which fourteen 4f electrons are added successively to the electronic configuration of lanthanum. The 4£ electrons are relatively uninvolved in bonding, so the whole series has a remarkably similar chemistry, for which the Sd16s2 1 2 outer electronic configuration of lanthanum is the prototype. All the lanthanides are highly electropositive and readily form tervalent ions. Although the tervalent state is always the most stable, certain ions are known to display variable valency. Cerium (4f1) and terbium (4f8) are known to exist as quadrivalentions, and samarium (4f5), 6 13 europium (4f) and ytterbium (4f ) form the bivalent ion. The reason for the existence of thesequadrivalentand bivalent states has been ascribed to the approach of formation of empty, half-full or full 4f orbitals. The shielding of one 4f electron by another is imperfect owing to the shapes of the f orbitals. For each successive lanthanide the effective nuclear charge experienced by each 4f electron increases, causing a reduction in size of the entire 4f shell. The accumulation of each successive contraction is the total lanthanide contraction. As a result tervalent lanthanum has a radius of 1.061 Acompared to 0.848 A for tervalent lutetium. 84 Yttrium has a similar outer shell electronic configuration and has many properties very similar to those of the lanthanides, especially erbium. This is because tervalent yttrium has a radius of 0.893 A compared to 0.881 A for tervalent erbium. For this reason yttrium, though not strictly a lanthanide, has been included in the scope of this work. The lanthanides exist in the natural state together, thus due to the similarity of their chemistry, separation of the lanthanides has been of some difficulty. The ions that show variable valency may be separated easily, but the remainder require special techniques. The most stable and common complexes of the lanthanides are those with chelating oxygen ligands. Water-soluble complexes of EDTA have been used in ion exchange separations. Due to the volatility of 3 complexes of S-diketones containing large organic groups or fluorine, various attempts have been made to separate the lanthanides by gas 28 81 chromatography. ' The volatility of these complexes is utilised in this work to obtain the mass spectra of the complexes. The coordination number either of a given lanthanide ion or for a series of lanthanide ions of the same charge appears to be determined more by spatial accommodation of the ligands than by the bonding charac­ teristics of the ligands.66 The coordination number in solution commonly differs from the coordination number in a crystal,given the same ligand and same lanthanide ion. The water molecule has a strong affinity for the lanthanide ion, and thus effectively competes for coordination sites. The coordination numbers of the complexes are rarely six,and higher coordination numbers (with coordinated waters) appear to be the rule. One of the first investigators of lanthanide complexes of S-diketones was Urbain (1886 to 1889). He prepared the hydrated tris(acetylacetonates) of lanthanum, yttrium and gadolinium. Interest in complexes of the lanthanides was greatly increased in the 1940's with the need to separate fission products. PART ONE PREPARATION OF THE LANTHANIDE CHELATES I. Preparation of Fluorinated 8-Diketone Ligands The preparation of the fluorinated 8-diketones was conducted as 35 described by Ho and Livingstone. The method is an example of a crossed Claisen condensation where a hydrogen ion is abstracted from the appropr i ate 1 y sub stitute. d acetoph enone b y means o f met h oxi"d e ions.. 58,60 The abstraction is selective for hydrogens adjacent to the carbonyl group. The resultant powerfully nucleophilic carbanion attacks the carbonyl carbon of ethyl trifluoroacetate to displace an ethoxide ion, yielding the desired fluorinated 8-diketone. The hydrogen ion abstraction may be carried out in the presence of the ethyltrifluoro­ acetate as it contains no hydrogens adjacent to the carbonyl group. The mechanism for the reaction is given in Figure 1.1. Purification of the fluorinated 8-diketone was done by complexation with copper(!!) ions. The 8-diketone was regenerated by hydrogen sulfide gas. The colour, melting point, and analytical data for the four fluorinated 8-diketones prepared are given in Table 1.1. Also included is 4,4,4-trifluoro-l-(2'-thienyl)-1,3-butanedione (obtained from Aldrich Chemicals) and l,l,l-trifluoro-5,5-dimethyl-2,4-hexanedione (obtained from PCR Research Chemicals). 22 In 1974 Das reported the preparation of several of the fluorinated 8-diketones used in this work. He prepared 4,4,4-trifluoro-l-(3'-methyl- phenyl)-1,3-butanedione, 4,4,4-trifluoro-1-(2'-methylphenyl)-l,3-butane- 5 R /CH2 /CF3 R /CH CF3 "'c 'c "c ~/ II II ~<-~-- II I 0 0 0 /0 \ /H H Figure 1.1.
Load more

Recommended publications
  • Chelation Effect of 2,4-Pentadione with Ni(II) and Cu(II) Ions
    Chemistry Research Journal, 2021, 6(2):48-57 Available online www.chemrj.org ISSN: 2455-8990 Research Article CODEN(USA): CRJHA5 Chelation Effect of 2,4-Pentadione with Ni(II) and Cu(II) Ions Terhemba, S. Iningev ⃰ , Aondoaver, J. Gbertyo Department of Chemistry, Benue State University, PMB 102119 Makurdi, Nigeria *Corresponding Author: [email protected] Abstract Synthesis of inorganic compounds with medical application is the aspect this work set to contribute. Ni(II) and Cu(II) chelates of2,4-pentadione (acetylacetone) were obtained from the reaction of hydrated divalent metal chloride salts with acetylacetone in aqueous ammonical medium. The complexes were prepared in order to examine the effect of chelation of 2,4-pentadione with metal ions, and antimicrobial activity on some pathogens. The compounds were characterised by infrared spectrophotometry. The absorption bands of the carbonyl group after coordination with Ni(II) and Cu(II) ions were lowered to1605 cm-1 and 1575cm-1, respectively. The spectral results suggest that there is a reduction in bond order of C=O after chelation, the consequence of resonance effect. The compounds were subjected to antimicrobial activity using Mueller Hinton agar and Sabouraud dextrose agar. Minimum Inhibition Concentration and Minimum Bacteria/Fungi Concentration were determined using serial broth dilution method. Ni(II) complex had shown significant antimicrobial activity on two fungi. Cu(II) complex on the other hand had shown wide biological activity on the tested microbes exception of P. milibilis. The metal chelates demonstrated better activities against the tested pathogens than the free ligand due to increase in permeability of the metal chelates through the microbe’s cell.
    [Show full text]
  • Cerium Tetrakis(Tropolonate) and Cerium Tetrakis(Acetylacetonate) Are Not Diamagnetic but Temperature-Independent Paramagnets
    UC Berkeley UC Berkeley Previously Published Works Title Cerium Tetrakis(tropolonate) and Cerium Tetrakis(acetylacetonate) Are Not Diamagnetic but Temperature-Independent Paramagnets. Permalink https://escholarship.org/uc/item/3tx9c6sw Journal Inorganic chemistry, 57(12) ISSN 0020-1669 Authors Halbach, Robert L Nocton, Grégory Booth, Corwin H et al. Publication Date 2018-06-04 DOI 10.1021/acs.inorgchem.8b00928 Peer reviewed eScholarship.org Powered by the California Digital Library University of California Article Cite This: Inorg. Chem. 2018, 57, 7290−7298 pubs.acs.org/IC Cerium Tetrakis(tropolonate) and Cerium Tetrakis(acetylacetonate) Are Not Diamagnetic but Temperature-Independent Paramagnets † † ‡ § ‡ ∥ Robert L. Halbach, Gregorý Nocton,*, , , Corwin H. Booth, Laurent Maron, † ‡ and Richard A. Andersen*, , † Department of Chemistry, University of California, Berkeley, California 94720, United States ‡ Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States § LCM, CNRS, Ecole Polytechnique, UniversitéParis Saclay, 91128 Palaiseau, France ∥ LPCNO, UMR 5215, CNRS, INSA, UPS, Universitéde Toulouse, 31000 Toulouse, France *S Supporting Information ABSTRACT: A new synthesis of cerium tetrakis(tropolonate), Ce(trop)4, where trop is deprotonated 2-hydroxy-2,4,6-cyclo- heptatrienone) or Ce(O2C7H5)4, is developed that results in dark- purple crystals whose X-ray crystal structure shows that the geometry of the eight-coordinate compound closely resembles a D2d dodecahedron, based on shape parameters. The magnetic susceptibility as a function of the temperature (4−300 K) shows that it is a temperature-independent paramagnet, χ = 1.2(3) × −4 10 emu/mol, and the LIII-edge X-ray absorption near-edge structure spectrum shows that the molecule is multiconfigura- tional, comprised of a f1:f0 configuration mixture in a 50:50 ratio.
    [Show full text]
  • Microwave-Assisted Synthesis of Coordination and Organometallic Compounds
    17 Microwave-assisted Synthesis of Coordination and Organometallic Compounds Oxana V. Kharissova, Boris I. Kharisov and Ubaldo Ortiz Méndez Universidad Autónoma de Nuevo León, Monterrey, México 1. Introduction Microwave irradiation (MW) as a “non-conventional reaction condition” (Giguere, 1989) has been applied in various areas of chemistry and technology to produce or destroy diverse materials and chemical compounds, as well as to accelerate chemical processes. The advantages of its use are the following (Roussy & Pearce, 1995): 1. Rapid heating is frequently achieved, 2. Energy is accumulated within a material without surface limits, 3. Economy of energy due to the absence of a necessity to heat environment, 4. Electromagnetic heating does not produce pollution, 5. There is no a direct contact between the energy source and the material, 6. Suitability of heating and possibility to be automated. 7. Enhanced yields, substantial elimination of reaction solvents, and facilitation of purification relative to conventional synthesis techniques. 8. This method is appropriate for green chemistry and energy-saving processes. The substances or materials have different capacity to be heated by microwave irradiation, which depends on the substance nature and its temperature. Generally, chemical reactions are accelerated in microwave fields, as well as those by ultrasonic treatment, although the nature of these two techniques is completely distinct. Microwave heating (MWH) is widely used to prepare various refractory inorganic compounds and materials
    [Show full text]
  • And Solar-Driven Fuel Synthesis with First Row Transition Metal Complexes † † Kristian E
    This is an open access article published under a Creative Commons Attribution (CC-BY) License, which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited. Review Cite This: Chem. Rev. 2019, 119, 2752−2875 pubs.acs.org/CR Electro- and Solar-Driven Fuel Synthesis with First Row Transition Metal Complexes † † Kristian E. Dalle, Julien Warnan, Jane J. Leung, Bertrand Reuillard, Isabell S. Karmel, and Erwin Reisner* Christian Doppler Laboratory for Sustainable SynGas Chemistry, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom ABSTRACT: The synthesis of renewable fuels from abundant water or the greenhouse gas CO2 is a major step toward creating sustainable and scalable energy storage technologies. In the last few decades, much attention has focused on the development of nonprecious metal-based catalysts and, in more recent years, their integration in solid-state support materials and devices that operate in water. This review surveys the literature on 3d metal-based molecular catalysts and focuses on their immobilization on heterogeneous solid-state supports for electro-, photo-, and photoelectrocatalytic synthesis of fuels in aqueous media. The first sections highlight benchmark homogeneous systems using proton and CO2 reducing 3d transition metal catalysts as well as commonly employed methods for catalyst immobilization, including a discussion of supporting materials and anchoring groups. The subsequent sections elaborate on productive associations between molecular catalysts and a wide range of substrates based on carbon, quantum dots, metal oxide surfaces, and semiconductors. The molecule−material hybrid systems are organized as “dark” cathodes, colloidal photocatalysts, and photocathodes, and their figures of merit are discussed alongside system stability and catalyst integrity.
    [Show full text]
  • (III) Acetylacetonate Derivatives by Solvothermal Method
    Lv et al. Int J Opt Photonic Eng 2017, 2:005 International Journal of Optics and Photonic VIBGYOR Engineering ISSN: 2631-5092 Composition and Fluorescence of Gadolinium (III) Acetyl- Research Article: Open Access Research acetonate Derivatives by Solvothermal Method Fengzhu Lv*, Yihe Zhang*, Xue Chen and Yong Ma Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences, Beijing, China Abstract Gadolinium (III) acetylacetonate was treated by solvothermal method to produce gadolinium complexes with acetylacetonate and -OH groups. The composition, fluorescence, and magnetic properties of the products were studied in detail. The fluorescence showed the products possessed higher energy emission and excitation fluorescence compared to Gadolinium (III) acetylacetonate. Also the product produced at 160 °C possessed higher fluorescent intensity and responding ability toward external magnetic field. So the products were hydrophobic materials with magnetic and fluorescent properties. Keywords Gadolinium (III) acetylacetonate derivatives, Solvothermal method, Luminescence Introduction fluorescence and magnetic properties, by simple method is the project of researchers [8,9]. Generally, rare earth complexes have many potential applications in novel lighting devices, optical fibers and Thermal decomposition of metal acetylacetonates has luminescent sensors benefiting from their long emission recently
    [Show full text]
  • A Roadmap for Metal Hydrides and Radicals Cite This: Chem
    Chemical Science View Article Online PERSPECTIVE View Journal | View Issue Catalytic hydrogen atom transfer to alkenes: a roadmap for metal hydrides and radicals Cite this: Chem. Sci., 2020, 11,12401 a b a b All publication charges for this article Sophia L. Shevick, Conner V. Wilson, Simona Kotesova, Dongyoung Kim, have been paid for by the Royal Society Patrick L. Holland *b and Ryan A. Shenvi *a of Chemistry Hydrogen atom transfer from a metal hydride (MHAT) has emerged as a powerful, if puzzling, technique in chemical synthesis. In catalytic MHAT reactions, earth-abundant metal complexes generate stabilized and unstabilized carbon-centered radicals from alkenes of various substitution patterns with robust chemoselectivity. This perspective combines organic and inorganic perspectives to outline challenges and opportunities, and to propose working models to assist further developments. We attempt to demystify the putative intermediates, the basic elementary steps, and the energetic implications, especially for cage pair formation, collapse and separation. Distinctions between catalysts with strong- Received 27th July 2020 field (SF) and weak-field (WF) ligand environments may explain some differences in reactivity and Accepted 28th September 2020 selectivity, and provide an organizing principle for kinetics that transcends the typical thermodynamic Creative Commons Attribution-NonCommercial 3.0 Unported Licence. DOI: 10.1039/d0sc04112b analysis. This blueprint should aid practitioners who hope to enter and expand this exciting area of rsc.li/chemical-science chemistry. 1. Introduction explained the reactions of hydridocyano- and hydridocarbo- nylmetal complexes with activated alkenes as outer-sphere Many impactful advances in synthesis have come from organ- additions of hydrogen, as opposed to coordinative metal ometallic chemistry, a eld that leverages the synergy between insertions, hydridic additions or protonations.5 MHAT is organic and inorganic chemistry.
    [Show full text]
  • Gas Chromatographic Determination of Lanthanide Mixed-Ligand Complexes of 1,1,1,2,2,6,6,7,7,7-Decafluoro-3,5-Heptanedione Charles Allen Burgett Iowa State University
    Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1972 Gas chromatographic determination of lanthanide mixed-ligand complexes of 1,1,1,2,2,6,6,7,7,7-decafluoro-3,5-heptanedione Charles Allen Burgett Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Analytical Chemistry Commons Recommended Citation Burgett, Charles Allen, "Gas chromatographic determination of lanthanide mixed-ligand complexes of 1,1,1,2,2,6,6,7,7,7-decafluoro-3,5-heptanedione " (1972). Retrospective Theses and Dissertations. 5889. https://lib.dr.iastate.edu/rtd/5889 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. iNFORivîATÎGN TO USERS This dissertation was produced from a microfilm copy of the original document. While the most advanced technological means to photograph and reproduce this document have been used, the quality is heavily dependent upon the quality of the original submitted. The following explanation of techniques is provided to help you understand markings or patterns which may appear on this reproduction. 1. The sign or "target" for pages apparently lacking from the document photographed is "Missing Page(s)". If it was possible to obtain the missing page(s) or section, they are spliced into the film along with adjacent pages. This may have necessitated cutting thru an image and duplicating adjacent pages to insure you complete continuity.
    [Show full text]
  • And Solar-Driven Fuel Synthesis with First Row Transition Metal Complexes † † Kristian E
    This is an open access article published under a Creative Commons Attribution (CC-BY) License, which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited. Review Cite This: Chem. Rev. 2019, 119, 2752−2875 pubs.acs.org/CR Electro- and Solar-Driven Fuel Synthesis with First Row Transition Metal Complexes † † Kristian E. Dalle, Julien Warnan, Jane J. Leung, Bertrand Reuillard, Isabell S. Karmel, and Erwin Reisner* Christian Doppler Laboratory for Sustainable SynGas Chemistry, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom ABSTRACT: The synthesis of renewable fuels from abundant water or the greenhouse gas CO2 is a major step toward creating sustainable and scalable energy storage technologies. In the last few decades, much attention has focused on the development of nonprecious metal-based catalysts and, in more recent years, their integration in solid-state support materials and devices that operate in water. This review surveys the literature on 3d metal-based molecular catalysts and focuses on their immobilization on heterogeneous solid-state supports for electro-, photo-, and photoelectrocatalytic synthesis of fuels in aqueous media. The first sections highlight benchmark homogeneous systems using proton and CO2 reducing 3d transition metal catalysts as well as commonly employed methods for catalyst immobilization, including a discussion of supporting materials and anchoring groups. The subsequent sections elaborate on productive associations between molecular catalysts and a wide range of substrates based on carbon, quantum dots, metal oxide surfaces, and semiconductors. The molecule−material hybrid systems are organized as “dark” cathodes, colloidal photocatalysts, and photocathodes, and their figures of merit are discussed alongside system stability and catalyst integrity.
    [Show full text]
  • Chiral, Heterometallic Lanthanide–Transition Metal Complexes by Design
    inorganics Article Chiral, Heterometallic Lanthanide–Transition Metal Complexes by Design Anders Øwre 1, Morten Vinum 1, Michal Kern 2 ID , Joris van Slageren 2 ID , Jesper Bendix 1,* and Mauro Perfetti 1,* ID 1 Department of Chemistry, University of Copenhagen, Universitetparken 5, 2100 Copenhagen, Danmark; [email protected] (A.Ø.); [email protected] (M.V.) 2 Institut für Physikalische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany; [email protected] (M.K.); [email protected] (J.v.S.) * Correspondence: [email protected] (J.B.); [email protected] (M.P.) Received: 15 June 2018; Accepted: 17 July 2018; Published: 19 July 2018 Abstract: Achieving control over coordination geometries in lanthanide complexes remains a challenge to the coordination chemist. This is particularly the case in the field of molecule-based magnetism, where barriers for magnetic relaxation processes as well as tunneling pathways are strongly influenced by the lanthanide coordination geometry. Addressing the challenge of design of 4f-element coordination environments, the ubiquitous Ln(hfac)3 moieties have been shown to be applicable as Lewis acids coordinating transition metal acetylacetonates facially leading to simple, chiral lanthanide–transition metal heterodinuclear complexes. The broad scope of this approach 0 is illustrated by the synthesis of a range of such complexes LnM: LnM(hfac)3(µ2-acac-O,O,O )3 (Ln = La, Pr, Gd; M = Cr, Fe, Ga), with approximate three-fold symmetry. The complexes have been crystallographically characterized and exhibit polymorphism for some combinations of 4f and 3d metal centers. However, an isostructural set of systems spanning several lanthanides which exhibit spontaneous resolution in the orthorhombic Sohncke space group P212121 is presented here.
    [Show full text]
  • Experimental Investigations of Thermodynamic
    EXPERIMENTAL INVESTIGATIONS OF THERMODYNAMIC PROPERTIES OF ORGANOMETALLIC COMPOUNDS Von der Fakultät für Ingenieurwissenschaften, Abteilung Maschinenbau und Verfahrenstechnik der Universität Duisburg-Essen zur Erlangung des akademischen Grades DOKTOR-INGENIEUR genehmigte Dissertation von Rehan Ahmad Siddiqui aus Lucknow, Indien Referent: Uni. Prof. Dr. rer. nat. habil Burak Atakan Korreferent: Uni. Prof. Dr. rer. nat. Ulrich Zenneck Tag der mündlichen Prüfung: 10-06-2009 Abstract i ABSTRACT Organometallic compounds are often volatile enough to be useful as precursors of the metals in vapor phase deposition process, e.g. chemical vapor deposition (CVD). For this process the precursor molecules are evaporated. To engineer such a process the knowledge of the vapor or sublimation pressures is essential because they determine the maximum theoretical growth rate and the composition. The gaseous diffusion coefficients for organometallic compounds are needed for the calculation of the Sherwood and Lewis numbers used to describe mass transfer process. Such data are either lacking or not well established. This work reports the thermal stability, vapor pressure and the gaseous diffusion coefficient for numerous organometallic compounds that are used as CVD precursors. These includes 1. Metal acetylacetonates ([M(acac)n]) of aluminium, chromium, iron, thulium, manganese, ruthenium, vanadium, dysprosium, zinc, copper and nickel. 2. Metal 2,2,6,6-tetramethyl-3,5-heptandionate ([M(tmhd)n]) of iron, manganese, aluminium, chromium, europium, nickel, and copper. 3. Metallocene ([M(cp)n]) of nickel and ruthenium. 4. Newly synthesized precursors or non commercial precursors of hafnium, zirconium, ruthenium, tungsten and copper. Some of the precursors were sensitive towards ambient atmosphere. Therefore, the samples were stored in the glove box.
    [Show full text]
  • Georg Garnweitner
    Aus dem Max-Planck-Institut für Kolloid- und Grenzflächenforschung Nichtwässrige Synthese und Bildungsmechanismus von Übergangsmetalloxid-Nanopartikeln Nonaqueous Synthesis of Transition-Metal Oxide Nanoparticles and Their Formation Mechanism Dissertation zur Erlangung des akademischen Grades "doctor rerum naturalium" (Dr. rer. nat.) in der Wissenschaftsdisziplin Kolloidchemie eingereicht an der Mathematisch-Naturwissenschaftlichen Fakultät der Universität Potsdam von Georg Garnweitner Potsdam, im Mai 2005 Die hier vorliegende Arbeit wurde in der Zeit von April 2003 bis Mai 2005 am Max-Planck- Institut für Kolloid- und Grenzflächenforschung in Potsdam/Golm angefertigt. Gutachter: Prof. Dr. Markus Antonietti Prof. Dr. Nicola Hüsing Dr. habil. Helmut Cölfen Tag der mündlichen Disputation: 24. 08. 2005 To my Family Abstract In this work, the nonaqueous synthesis of binary and ternary metal oxide nanoparticles is investigated for a number of technologically important materials. A strong focus was put on studying the reaction mechanisms leading to particle formation upon solvothermal treatment of the precursors, as an understanding of the formation processes is expected to be crucial for a better control of the systems, offering the potential to tailor particle size and morphology. The synthesis of BaTiO3 was achieved by solvothermal reaction of metallic barium and titanium isopropoxide in organic solvents. Phase-pure, highly crystalline particles about 6 nm in size resulted in benzyl alcohol, whereas larger particles could be obtained in ketones such as acetone or acetophenone. In benzyl alcohol, a novel mechanism was found to lead to BaTiO3, involving a C–C coupling step between the isopropoxide ligand and the benzylic carbon of the solvent. The resulting coupling product, 4-phenyl-2-butanol, is found in almost stoichiometric yield.
    [Show full text]
  • METAL ACETYLACETONATES and THEIR PROPERTIES by EVRIM
    METAL ACETYLACETONATES AND THEIR PROPERTIES By EVRIM ARSLAN A Dissertation submitted to the Graduate School-Newark 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 Professor Roger Lalancette and approved by ________________________ ________________________ ________________________ ________________________ Newark, New Jersey October, 2019 © 2019 EVRIM ARSLAN ALL RIGHTS RESERVED ABSTRACT OF THE DISSERTATION METAL ACETYLACETONATES AND THEIR PROPERTIES By Evrim Arslan Dissertation Director: Professor Roger Lalancette Metal acetylacetonates are significant since they were amongst the earliest metal compounds which were recognized as what later became known as coordination compounds. Additionally, they were significantly investigated during WWII as potentially useful in the separation of isotopes, especially of uranium because of their unexpected volatility. Consequently, much research was carried out over the years— a good deal of which was of suspect validity, which unfortunately cannot be checked because very little information was published on the syntheses and crystallization methods used in the preparation of the crystalline samples. Here, we report our efforts to clean the slate by reporting on those of Al(III), Mn(III), Co(III), Cr(III), Fe(III), V(III) and Ti(III). These studies were carried out with crystalline samples obtained from a wide variety of solvents and over the range 296-100K in attempts to reproduce, verify, and correct, at times, the claims made in print. Our results, covering over 100 samples, are detailed in this thesis. We have also made crystallographic measurements at temperatures other than 100K and 296K for crystals of Al(acac)3 and Mn(acac)3 guided by their thermochemical information using DSC and Cp measurements.
    [Show full text]