- PREPARATION OF Rb2NaYF6:Ce3 + AND Cs2NaYF6:Ce3 + - A PROSPECT FOR TUNABLE LASERS IN THE BLUE-GREEN WAVELENGTH.
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A systematic study of the systems RbF-NaF-YF//3 and NaF-CsF-YF//3 has been made in order to synthesize Ce**3** plus -doped Rb//2NaYF//6 and Cs//2NaYF//6. Based on preliminary results of the absorption fluorescence efficiency, lifetime, and excited-state absorption, we conclude that a series of compounds (in the form of single crystals) of the general form A//2BYF//6:Ce**3** plus is a worthy prospect for a broad-band, wavelength tunable laser from 400 to 480 mu m which makes it attractive for optical communication.
- Mroczkowski,Dorain
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- Jahn-Teller ordering in Kagome-type layers of compounds A2A′MnIII3F12 (A = Rb, Cs; A′ = Li, Na, K)
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For a series of new Mn(III) fluorides the crystal structures have been determined by X-ray diffraction on single crystals: Cs2LiMn3F12, space group R3, Z = 3 (merohedral twin), a = 7.440(1), c = 17.267(3) A, R = 1.95%; three isostructural triclinic phases, space group P1, Z = 2, Cs2NaMn3F12, a = 7.305(1), b = 7.512(1), c = 10.376(2) A, α = 89.89(3)°, β = 87.32(3)°, γ = 89.89(3)°, R = 2.75%; Rb2NaMn3F12, a = 7.115(1), b = 7.482(1), c = 10.160(2) A, α = 89.92(3)°, β = 86.52(3)°, γ = 89.51(3)°, R = 2.70%; Rb2LiMn3F12, a = 6.883(1), b = 7.481(1), c = 10.194(2) A, α = 89.42(3)°, β = 87.16(3)°, γ = 90.25(3)°. R = 4.87%; monoclinic Cs2KMn3F12, space group C2/c, Z = 4, a = 13.112(3), b = 7.571(2), c = 12.672(3) A, β = 108.79(3)°, R = 5.3%. All structures derive from the Cs2NaAl3F12 parent structure and consist of [Mn3F12] layers of corner-sharing octahedra of the Kagome-net-type (3+6 octahedra units like in the hexagonal tungsten bronze layers). The [MnF6] octahedra are strongly elongated by the Jahn-Teller effect with ratios of long to short axes of about 1.15. In all structures the long axes are oriented within the layers in an alternating wind-wheel-like pattern corresponding to an antiferrodistortive Jahn-Teller ordering. Thus, all Mn-F-Mn bridges are asymmetric; the bridge angles are between 136° and 141°. Magnetic investigations of Cs2NaMn3F12 and Cs2KMn3F12 indicate similar antiferromagnetic exchange interactions (J/k = -2.5 K), but only for the Cs2K compound has 2D and 3D ordering been found at low temperatures. The results are discussed in context with the Jahn-Teller ordering and the 'frustrated' exchange situation in the Kagome net.
- Englich, Ulrich,Frommen, Christoph,Massa, Werner
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- Complexes of xenon oxide tetrafluoride
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Xenon oxide tetrafluoride bears a strong resemblance to the halogen fluorides both in physical properties and chemical behavior. A number of physical properties of XeOF4 have been measured. Xenon oxide tetrafluoride is a clear, colorless liquid freezing at -46.2°. Its electrical conductivity at 24° is 1.03 × 10-5 ohm-1 cm.-1 and its dielectric constant is 24.6 at 24°. It is miscible with anhydrous HF, but its conductivity is not enhanced in such a solution. The addition of CsF or RbF to XeOF4 increases its conductivity markedly. Xenon oxide tetrafluoride forms a series of addition compounds with the heavier alkali fluorides. The following complexes have been isolated: CsF·XeOF4, 3RbF-2XeOF4 and 3KF·-XeOF4. No reaction occurs with NaF. Thermogravimetric studies show that a number of intermediates are formed before final decomposition to the alkali fluorides. Xenon oxide tetrafluoride reacts with SbF5 to form a complex of composition XeOF4· 2SbF5. A reaction also occurs with AsF5 at -78°, but the complex is unstable at room temperature.
- Selig, Henry
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- On the crystal structure of pyrochlores: Moessbauer spectra of orthorhombic CsFe2F6 and X-ray single crystal studies of the cubic compounds CsMgGaF6, CsMIIVIIIF 6 (MII = Mn, Zn), CsMIIFeIIIF 6 (MII = Mn, Cu, Zn), and Cs4Cu 5V3O ...
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Title full: On the crystal structure of pyrochlores: Moessbauer spectra of orthorhombic CsFe2F6 and X-ray single crystal studies of the cubic compounds CsMgGaF6, CsMIIVIIIF 6 (MII = Mn, Zn), CsMIIFeIIIF 6 (MII = Mn, Cu, Zn), and Cs4Cu 5V3O2F19. Orthorhombic CsFe2F6 (a = 749.1(3), b = 723.8(3), c = 1043.1(6) pm; V = 565.6(9) A3, Z = 4, Imma?) was prepared with strongly 57Fe doped FeF3 and its Moessbauer spectra measured. It is in accordance with the spectra of a natural 57Fe abundance sample, also with respect to the intensity ratio Fe II:FeIII = 1:1. For the formation of an ordered pyrochlore structure in spite of quenching thus an electronically induced phase transition should be responsible, explaining the MII/MIII order observed in all mixed valence pyrochlores AIMIIM IIIF6. By contrast, single crystals of CsMgGaF6 (a = 1021.6(1) pm), CsMnVF6 (a = 1058.9(1) pm), CsMnFeF6 (a = 1054.6(1) pm), CsZnVF6 (a = 1041.5(1) pm, CsZnFeF6 (a = 1042.1(1) pm) and CsCuFeF6 (a = 1037.7(2) pm), obtained by solid state reaction and slow cooling, all exhibit the cubic pyrochlore structure of the RbNiCrF6 type (Z = 8, Fd3m), in which the cations M II/MIII are disordered in position (16c). An oxidfluoride of approximate composition Cs4Cu5V3O 2F19 (a = 1022.2(1) pm) has the same structure, but in addition it shows a disordered occupation of the position (48f) by lack of about 1/8 of anions. Structural relations and distances for the cubic crystal structures refined (R between 0.02 and 0.06) are discussed.
- Baum, Elke,Dahlke, Patrik,Kaiser, Volker,Molinier, Michel,Schmidt, Roland E.,Pebler, Juergen,Massa, Werner,Babel, Dietrich
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- Soluble diamagnetic model for malaria pigment: Coordination chemistry of gallium(III)protoporphyrin-IX
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The facile axial ligand exchange properties of gallium(III) protoporphyrin IX in methanol solution were utilized to explore self-association interactions by NMR techniques. Structural changes were observed, as well as competitive behavior with the ligands acetate and fluoride, which differed from that seen with the synthetic analogue gallium(III) octaethylporphyrin which lacks acid groups in its side-chains and has less solution heterogeneity as indicated by absorption and MCD spectroscopies. The propionic acid side chains of protoporphyrin IX are implicated in all such interactions of PPIX, and both dynamic metal-propionic interactions and the formation of propionate-bridged dimers are observed. Fluoride coordination provides an unusual example of slow ligand exchange, and this allows for the identification of a fluoride bridged dimer in solution. An improved synthesis of the chloride and hydroxide complexes of gallium(III) protoporphyrin IX is reported. An insoluble gallium analogue of hematin anhydride is described. In general, the interactions between solvent and the metal are found to confer very high solubility, making [Ga(PPIX)] + a useful model for ferric heme species.
- Bohle, D. Scott,Dodd, Erin L.,Pinter, Tyler B. J.,Stillman, Martin J.
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- Thermal stability and X-ray-luminescent properties of fluorozirconates and fluorosulfatozirconates
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The thermolysis of fluorozirconates (M2ZrF6, M 5Zr4F21 ? 3H2O, MZrF 5 ? H2O, Rb2Zr3OF12, and Cs2Zr3F14/sub
- Godneva,Boroznovskaya,Motov,Klimkin,Mikhailova
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- Synthesis of Monosubstituted Trifluoromethylated Derivatives of 2H-thiete, Dihydrothiophenes, and 2H-thiopyrans
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[Figure not available: see fulltext.] Cyclic keto sulfides (thietan-3-one, tetrahydrothiophen-3-one, γ-thiobutyrolactone, δ-thiovalerolactone, thiopyran-3-one, and thiopyran-4-one) react with trifluoromethyltrimethylsilane (Ruppert–Prakash reagent) to aff
- Siryi, Serhii A.,Тimoshenko, Vadim М.,Rudenko, Tymofii V.,Markitanov, Yuriy M.,Rusanov, Eduard B.,Shermolovich, Yuriy G.
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p. 106 - 115
(2022/04/03)
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- Development of technology of perfluoroethyl isopropyl ketone production
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Synthesis of perfluoroethyl isopropyl ketone by an interaction of hexafluoropropene with perfluoropropionic acid fluoride or hexafluoropropene oxide was examined. Interchangeability of perfluoropropionic acid fluoride and hexafluoropropene oxide was demonstrated. The features of perfluoroethyl isopropyl ketone synthesis were studied in polar aprotic solvents on catalysts: alkali metal fluoride. A method for obtaining perfluoroethyl isopropyl ketone by direct catalytic reaction in a tubular reactor without use of solvents was suggested and investigated. The mechanism of interaction was considered. The main impurities resulting in obtaining perfluoroethyl isopropyl ketone were determined. The methods of cleaning perfluoroethyl isopropyl ketone were worked out.
- Fenichev,Babenko,Bispen,Moldavskii
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p. 376 - 386
(2013/07/05)
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- XeOF3-, an example of an AX3YE2 valence shell electron pair repulsion arrangement; Syntheses and structural characterizations of [M][XeOF3] (M = Cs, N(CH3) 4)
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The XeOF3- anion has been synthesized as its Cs + and N(CH3)4+ salts and structurally characterized in the solid state by low-temperature Raman spectroscopy and quantum-chemical calculations. Vibrational frequency assignments for [Cs][XeOF3] and [N(CH3) 4][XeOF3] were aided by 18O enrichment. The calculated anion geometry is based on a square planar AX3YE 2 valence-shell electron-pair repulsion arrangement with the longest Xe-F bond trans to the oxygen atom. The F-Xe-F angle is bent away from the oxygen atom to accommodate the greater spatial requirement of the oxygen double bond domain. The experimental vibrational frequencies and trends in their isotopic shifts are reproduced by the calculated gas-phase frequencies at several levels of theory. The XeOF3- anion of the Cs + salt is fluorine-bridged in the solid state, whereas the anion of the N(CH3)4+ salt has been shown to best approximate the gas-phase anion. Although [Cs][XeOF3] and [N(CH 3)4][XeOF3] are shock-sensitive explosives, the decomposition pathways for the anions have been inferred from their decomposition products at 20°C. The latter consist of XeF2, [Cs][XeO2F3], and [N(CH3)4][F]. Enthalpies and Gibbs free energies of reaction obtained from Born-Fajans-Haber thermochemical cycles support the proposed decomposition pathways and show that both disproportionation to XeF2, [Cs][XeO2F3], and CsF and reduction to XeF2, CsF, and O2 are favorable for [Cs][XeOF3], while only reduction to XeF2 accompanied by [N(CH3)4][F] and O2 formation are favorable for [N(CH3)4][XeOF3]. In all cases, the decomposition pathways are dominated by the lattice enthalpies of the products.
- Brock, David S.,Mercier, Helene P. A.,Schrobilgen, Gary J.
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p. 10935 - 10943
(2010/09/16)
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- Dinuclear fluoro-peroxovanadium(v) complexes with symmetric and asymmetric peroxo bridges: Syntheses, structures and DFT studies
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Two new dinuclear fluoro peroxovanadium(v) complexes, Cs3[V 2O2(O2)4F]·H2O (1) and Cs3[V2O2(O2)3F 3]·2HF·H2O (2)
- Chrappova, Jana,Schwendt, Peter,Sivak, Michal,Repisky, Michal,Malkin, Vladimir G.,Marek, Jaromir
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p. 465 - 473
(2009/04/12)
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- Single crystal structural studies at hexagonal fluoride perovskites AMIIF3 (MII = Mg, Mn, Fe, Co, Ni)
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At single crystals of nine fluoride phases AMF3 the hexagonal perovskite structures were refined by X-ray methods, of RbNiF3 below TC ≈ 145 K, too. The hexagonal 6 L type (P63/mmc, Z = 6) is found at: RbMgF3 (a = 585.7(1); c = 1426.0(1) pm), CsMnF3 (624.4(1); 1515.4(4) pm), CsFeF3 (616.8(1); 1488.4(6) pm), Rb0.63Cs0.37CoF3 (599.1(1); 1460.3(4) pm), RbNiF3 (128 K: 582.6(1); 1426.4(6) pm), Cs2BaLiNi2F9 (593.1(1); 1447.1(4) pm). Of the hexagonal-rhombohedral 9 L type (R 3 m, Z = 9) are CsCoF3 (620.1(1); 2264.0(7) pm) and yellow CsNiF3 (614.7(1); 2235.3(6) pm), prepared at lower temperatures resp. under high pressure, whereas light green CsNiF3 (625.5(1); 524.2(1) pm) belongs to the 2 L type (P63/mmc, Z = 2). The occurence of these structures and the interatomic distances observed, comparing also normal and high pressure phases, are discussed in connection with the tolerance factor.
- Schmidt,Welsch,Kummer-Doerner,Babel
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p. 637 - 642
(2008/10/08)
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- Vibrational Spectra and Structural Aspects of Fluorosulfites
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The Raman and infrared spectra of the fluorosulfites of K+, Rb+, Cs+, NH4+, and Me4N+ have been examined. Previous assignment of the fundamental vibrations is revised, and an ab initio study of the SO2F- anion is presented. For the pyramidal anion of symmetry Cs, distances of r(S-O) = 1.458 ? and r(S-F) = 1.698 ? have been calculated. The heat of formation of Me4NSO2F (-14.0 kcal/mol) was derived from the dissociation pressure of the salt. In addition, the lattice energy of Me4NF (159.2 kcal/mol) was calculated from a thermochemical cycle. The thermochemical data are discussed in terms of reactivity of the fluorides and stability of the fluorosulfites.
- Kornath, Andreas,Neumann, Frank,Ludwig, Ralf
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p. 5570 - 5573
(2008/10/09)
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- Fluorine-oxygen exchange reactions in IF5, IF7, and IF5O
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When reacted with alkali-metal nitrates, IF5 readily exchanges two fluorine ligands for a doubly bonded oxygen atom. In all cases MIF4O salts (M = Li, K, Cs) and FNO2 are formed as the primary products. The FNO2 byproduct undergoes a fast secondary reaction with MNO3 to yield equimolar amounts of N2O5 and MF. The N2O5 decomposes to N2O4 and 0.5 mol of O2, while the MF, depending on the nature of M, does or does not undergo complexation with the excess of IF5. Pure MIF4O salts, free of MF or MF·nIF5 byproducts, were prepared from MF, I2O5, and IF5 in either CH3CN or IF5 as a solvent. The new compounds LiIF4O, NaIF4O, RbIF4O, and NOIF4O were characterized by vibrational spectroscopy. It was also shown that, contrary to a previous report, FNO2 does not form a stable adduct with IF5 at temperatures as low as -78°C. An excess of IF7 reacts with MNO3 (M = Li, Na) to give MF, FNO2, IF5, and 0.5 mol of O2, but surprisingly no IF5O. With CsNO3, the reaction products are analogous, except for the CsF reacting with both the IF5 product and the excess of IF7 to give CsIF6·2IF5 and CsIF8, respectively. When in the IF7 reaction an excess of LiNO3, is used, the IF5 product undergoes further reaction with LiNO3, as described above. The IF5O molecule was found to be rather unreactive. It does not react with either LiF or CsF at 25 or 60°C or with LiNO3 or CsNO3 at 25°C. At 60°C with LiNO3, it slowly loses oxygen, with the IF5 product reacting to yield LiIF4O, as described above.
- Christe, Karl O.,Wilson, William W.,Wilson, Richard D.
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p. 904 - 908
(2008/10/08)
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- Alkali-metal Heptafluorodiarsenates(III): their Preparation and the Crystal Structure of the Potassium Salt
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Heptafluorodiarsenates(III), MAs2F7 (M=K, Rb, or Cs), have been prepared by the dissolution of the alkalimetal fluoride in arsenic trifluoride and crystallisation from the solvent at room temperature.Loss of arsenic trifluoride and formation of the tetrafluoroarsenate(III) occurs on heating to 100 deg C under vacuum.The structure of the potassium salt has been determined by the heavy-atom method from 799 reflections, and refined by full-matrix least-squares methods to R 0.070.Crystals are monoclinic, space group P21/c, with a=10.99(1), b=7.39(1), c=8.75(1) Angstroem, and β=110.8(2)o.The structure consists of potassium ions, tetrafluoroarsenate(III) ions, and arsenic trifluoride molecules, with some interaction between anions and molecules to form a complex chain arrangement.
- Edwards, Anthony J.,Patel, Shantubai N.
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p. 1630 - 1632
(2007/10/02)
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