A Spectroscopic Study of Outer-Sphere Interaction in M3UO2F5 Complexes

The data available in literature on the vibration spectra of complex uranyl compounds indicate that the stretching vibration frequencies of the UO²⁺ ₂ group depend not only on the composition of the coordination sphere, but also on the outer surrounding of the complex anion. The outer-sphere cation, in case of uranyl complexes, acts as a competitor of the uranyl group to form bonds with, ligands. At the same time, as a result of decrease in the electron density localised on the U-F bonds, the strength of these bonds becomes less.     

Polarized Laser Raman Spectra of the Crystal Cs3UO2F3

Abstract

Polarized Raman spectra of Cs₃UO₂F₅ in which the UO₂F₅ ^3? ion is in its statistical position have made it possible to assign definitely the Raman fundamental vibration modes as follows : v₁(A′¹) = 784, v₂(A′¹) = 423, v₈(E′²) = 325, v₈(E′²) = 219 and v₁₀(E″¹) = 259 cm^?1.     

Adsorption of UO2 2+ from Aqueous Solutions by Inorganic Exchangers

Various natural and treated clays as well as some synthetic exchangers have been used to remove UO₂ ²⁺ from aqueous solutions. Different factors which affect the adsorption process such as time, pH, competing ions … etc were studied. The mechanism of adsorption was found to be under film diffusion control. It was concluded that the naturally occuring clays are suitable as adsorbent for UO₂ ²⁺ and their capacities are comparable, if not better than those treated clays or synthetic exchangers.

Es werden unterschiedliche natürliche und vorher behandelte Tonarten als auch einige synthetische Anstauschcr zur Abtrennung von UO₂ ²⁺ aus wäβrigen Lösungen eingeselzt. Verschiedene Faktoren, die den Adsorptionsprozeβ beeinflussen, wie die Zeitdauer, der pH-Wert, andere konhurrierende Ionen u. ä. m. wurden untersucht. Es stellte sich heraus, daβ der Adsorptionsmechanismus durch eine Filmdiffusion kontrolliert wird. Dienatürlich vorkommenden Tonesind durchaus als Adsorbentien fur UO₂ ²⁺ geeignet und ihre Aufnahmekapzitäten sind vergleichbar, wenn nicht mit unter besser als jene, die bei behandelten Tonen oder synthetischen Austauschem gefunden werden.     

Raman spectroscopic study of the uranyl mineral metauranospinite Ca[(UO2)(AsO4)]2·8H2O

Raman spectra of metauranospinite Ca[(UO₂)(AsO₄)]₂·8H₂O complemented with infrared spectra were studied. Observed bands were assigned to the stretching and bending vibrations of (UO₂)²⁺ and (AsO₄)³⁻ units and of water molecules. U O bond lengths in uranyl and O H···O hydrogen bond lengths were calculated from the Raman and infrared spectra. Copyright © 2009 John Wiley & Sons, Ltd.     

Luminescence of Rb3UO2F5 Crystals in Selective Laser Excitation

The characteristic features of the low-temperature (6 K) luminescence of Rb₃UO₂F₅ crystals in resonant selective laser excitation within an inhomogeneously broadened contour of a phonon-free line have been investigated. The presence of a nonselective spectral migration of the electron-excitation energy over a subsystem of uranylfluoride complexes is established. The energy migration is due to the Raman scattering of crystal phonons and is associated with the interaction of the lower excited energy levels of the uranyl complex, which leads to a disturbance of adiabaticity.     

Raman spectroscopic study of the uranyl mineral natrouranospinite (Na2,Ca)[(UO2)(AsO4)]2· 5H2O

Raman spectra of natrouranospinite complemented with infrared spectra were studied and related to the structure of the mineral. Observed bands were assigned to the stretching and bending vibrations of (UO₂)²⁺ and (AsO₄)³⁻ units and of water molecules. U O bond lengths in uranyl and O H···O hydrogen bond lengths were calculated from the Raman and infrared spectra. Copyright © 2009 John Wiley & Sons, Ltd.     

Raman spectroscopic study of the uranyl phosphate mineral dumontite Pb2 [(UO2)3O2(PO4)2]·5H2 O

Raman spectra of dumontite were measured at 298 and 77 K. Observed bands were attributed to the stretching and bending vibrations of uranyl and phosphate units and OH stretching vibrations of water molecules. U–O bond lengths in uranyls and approximate O–H···O bond lengths were calculated. The values of the U–O bond lengths are in agreement with the data from the single crystal structure analysis of dumontite. Copyright © 2008 John Wiley & Sons, Ltd.     

Electron spectra of Me7Eu2UO2(PO4)5 crystals

Absorption and luminescence spectra of Me₇Eu₂UO₂(PO₄)₅ crystals (Me represents Na, Rb, or Cs) are investigated. It is established that the luminescence of Eu³⁺ ions in these crystals is sensitized by uranyl. The effect of the outer-sphere cation Me⁺ on the spectroscopic properties and structural features of the compounds under study is considered. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 1, pp. 89–94, January–February, 1999.     

Raman spectroscopic study of the uranyl mineral,compreignacite, K2[(UO2)3O2(OH)3]2·7H2O

Raman spectra of the uranyl oxyhydroxy‐hydrated mineral compreignacite, K₂[(UO₂)₃O₂(OH)₃]₂·7H₂O, were measured and interpreted. Observed bands were attributed to the stretching and bending vibrations of uranyl units, molecular water and hydroxyl ions. U O bond lengths in uranyl and O HO hydrogen bond lengths were inferred from the spectra and compared with those from the X‐ray single crystal structure data. The importance of this spectroscopic study rests with the ability to analyze very small amounts of the mineral. Copyright © 2008 John Wiley & Sons, Ltd.     

Temperature Dependence of Integrated Intensity Bands in IR-Absoption Spectra of (NH4)2AF6 Complexes

The contribution refers to the temperature dependence of IR-absorption spectra (NH₄)₂AF₆ (A - Si and Ge). It is found that with temperature decreasing, the integrated intensities of the bands corresponding to anion fundamentals, increase, while those of cation, decrease. An explanation is given to the phenomena detected, which is based on variations in the strength of the outer-sphere interaction with the temperature, and subsequent redistribution of electron density.     

The vibrational spectra and structural properties of Me7Eu2UO2(PO4)5 crystals

We investigate the vibrational spectra of crystals of ternary orthophosphates Me₇Eu₂UO₂·(PO₄)₅ (Me–Na, Rb, Cs) obtained by solid-phase synthesis. We show that in these materials the effect of coordination distorts the geometry of the PO ₄ ³⁻ tetrahedron and decreases its symmetry. We conclude that the PO ₄ ³⁻ tetrahedrons in Me₇Eu₂UO₂(PO₄)₅ occupy two nonequivalent positions in the lattice. The character of manifestation and the number of oscillation frequencies observed allow the assumption that they have the C_3v- and C₂-symmetry. This symmetry of two crystallographically nonequivalent groups of PO ₄ ³⁻ ensures a complete set of bands in the IR absorption spectra of the crystals investigated. We show that these crystals exhibit chain structural motifs. Translated from Zhurnal Prikladnoi Spektroskopii, Vol, 64, No. 4, pp. 467–470, July–August, 1997.     

Raman spectroscopic study of the uranyl mineral pseudojohannite Cu6.5[(UO2)4O4(SO4)2]2(OH)5·25H2O

Raman spectra of pseudojohannite were studied and related to the structure of the mineral. Observed bands were assigned to the stretching and bending vibrations of (UO₂)²⁺ and (SO₄)²⁻ units and of water molecules. The published formula of pseudojohannite is Cu_6.5(UO₂)₈[O₈](OH)₅[(SO₄)₄]·25H₂O. Raman bands at 805 and 810 cm⁻¹ are assigned to (UO₂)²⁺ stretching modes. The Raman bands at 1017 and 1100 cm⁻¹ are assigned to the (SO₄)²⁻ symmetric and antisymmetric stretching vibrations. The three Raman bands at 423, 465 and 496 cm⁻¹ are assigned to the (SO₄)²⁻ν₂ bending modes. The bands at 210 and 279 cm⁻¹ are assigned to the doubly degenerate ν₂ bending vibration of the (UO₂)²⁺ units. U O bond lengths in uranyl and O H···O hydrogen bond lengths were calculated from the Raman and infrared spectra. Copyright © 2009 John Wiley & Sons, Ltd.     

Raman spectroscopic study of the uranyl selenite mineral marthozite Cu[(UO2)3(SeO3)2O2]·8H2O

The mineral marthozite, a uranyl selenite, has been characterised by Raman spectroscopy at 298 K. The bands at 812 and 797 cm⁻¹ were assigned to the symmetric stretching modes of the (UO₂)²⁺ and (SeO₃)²⁻ units, respectively. These values gave the calculated U O bond lengths in uranyl of 1.799 and/or 1.814 Å. Average U O bond length in uranyl is 1.795 Å, inferred from the X‐ray single crystal structure analysis of marthozite by Cooper and Hawthorne. The broad band at 869 cm⁻¹ was assigned to the ν₃ antisymmetric stretching mode of the (UO₂)²⁺ (calculated U O bond length 1.808 Å). The band at 739 cm⁻¹ was attributed to the ν₃ antisymmetric stretching vibration of the (SeO₃)²⁻ units. The ν₄ and the ν₂ vibrational modes of the (SeO₃)²⁻ units were observed at 424 and 473 cm⁻¹. Bands observed at 257, and 199 and 139 cm⁻¹ were assigned to OUO bending vibrations and lattice vibrations, respectively. O H···O hydrogen bond lengths were inferred using Libowiztky's empirical relation. The infrared spectrum of marthozite was studied for complementation. Copyright © 2008 John Wiley & Sons, Ltd.     

K7[P2Mo4W13M(H2O)O61]及其有机复合材料的合成及光谱研究

用降解法制得了Dawson结构铬、铁取代的磷钼钨酸钾,并将其与溴化(E)-N-丁基-4-(2-(4-二甲氨基苯基)乙烯基)吡啶反应制备了有机复合材料.通过元素分析和TG-DTA确定了配合物的组成分别为K7[P2Mo4W13M(H2O)O61](M=Cr(1),Fe(2))和(C19H25N2)6K3[P2Mo4W13MO62](M=Cr(3),Fe(4)).利用红外光谱、紫外-可见光谱、固体漫反射紫外-可见-近红外光谱、X射线光电子能谱以及荧光光谱对上述化合物进行了表征,并研究了复合材料中无机与有机组分间的相互作用及其荧光性质.     

Mössbauer study of (NH4)2FeCl5.H2O

We report Mössbauer data between 1.3K and 300K, with applied fields of up to 10T at 4.2K, of (NH₄)₂FeCl₅.H₂O. We found no evidence of a reported structural phase change just above T_N(～7.3K), nor did we see any spin reorientation just below T_N. The V₂₂ axis was found to be in the ac plane at ～17° to the a axis and the spins, below T_N, were found to be approximately parallel to the a axis. The spin reorientation in applied field occured gradually between 0T and 5T; this and previously reported susceptibilty data have led to the hypothesis that (NH₄)₂FeCl₅.H₂O is a weak ferromagnet.     

Raman spectroscopic study of the mineral guilleminite Ba(UO2)3(SeO3)2(OH)4·3H2O

The Raman spectrum of the mineral guilleminite Ba[(UO₂)₃O₂(SeO₃)₂](H₂O)₃ was studied and complemented by the infrared spectrum of this mineral. Both spectra were interpreted and compared with the spectra of marthozite, larisaite, haynesite and piretite, all of which should have the same phosphuranylite anion sheet topology. The presence of symmetrically distinct water molecules and hydrogen bonds was inferred from the spectra. This is in agreement with the crystal structural analysis of guilleminite. U O bond lengths in uranyl and O H···O hydrogen bond lengths were calculated from the Raman and/or infrared spectra of guilleminite. Copyright © 2008 John Wiley & Sons, Ltd.     

IR-Spectral Study of 2-Aminopyridine and Aniline Complexes with Palladium (II)

An IR-spectral study of sulphato- and chloro complexes of palladium (II) with 2-aminopyridine and aniline, respectively, is reported. The results obtained confirm the bidentate co-ordination of both 2-aminopyridine and SO₄ group in the case of sulphato-2-aminopyridine-palladium (II) leading to polynuclear structure of the complex in solution. The comparative investigation of sulphato-dianiline-palladium (II) suggests that the self-dependent ability of the SO₄ ^2- ion for bridging co-ordination can stabilize chain-like complexes of palladium (II) only in the solid state.