Crystal Structure of the Sodium Salt of the Uranyl--Oxyacetate--Fluoride Dimer, Na4(UO2)2(OCH2COO)2F4.6H2O.

Farkas, I; Csöregh, Ingeborg; Szabó, Zoltán; Frölich, Roland; Sillesen, Alfred; Mønsted, O.; Rasmussen, Jens C.; Toftlund, Hans

doi:10.3891/acta.chem.scand.53-1009

Cited by 8 publications

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“…All these distances are close to those found in the solid compounds M 2 (OCH 2 CO 2 ) 2 -(HOCH 2 CO 2 ) 2 ؒ4H 2 O, M = Dy, Er, that contain bridging oxoacetate ligands. 5, 20 There are only 1.3 carbons per Th, lower than the expected two or three. The reason for this discrepancy is mainly due to the small contribution of this shell to the EXAFS scattering.…”

Section: Structure and Bondingmentioning

confidence: 79%

Complexation of Th(iv) and various lanthanides(iii) by glycolic acid; potentiometric,¹³C-NMR and EXAFS studies

Toraishi

Farkas

Szabó

et al. 2002

J. Chem. Soc., Dalton Trans.

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Section: Structure and Bondingmentioning

confidence: 79%

Complexation of Th(iv) and various lanthanides(iii) by glycolic acid; potentiometric,¹³C-NMR and EXAFS studies

Toraishi

Farkas

Szabó

et al. 2002

J. Chem. Soc., Dalton Trans.

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“…This implies the formation of a dimer, most likely similar to [(UO 2 ) 2 (OCH 2 COO) 2 F 4 ] 4− [16], where the oxo-group is bridging the two uranium atoms and where the fluorides are replaced by a chelated (OCH 2 COO) 2− .…”

Section: Exafs Measurementsmentioning

confidence: 98%

“…The data were treated using the EXAFSPAK suite of programs [14]. Theoretical backscattering phase and amplitude functions, δ(k) and F(k), used in data analysis were calculated for the model compounds UO 2 (CH 3 COO) 2 ·2H 2 O [15] and Na 4 (UO 2 ) 2 (OCH 2 COO) 2 F 4 ·6H 2 O [16] using the theoretical EXAFS modeling code, FEFF6 [17]. The multiple scattering paths U−O (axial, 4-legged path), U−C−C (3-and 4-legged paths), and U−C−O (3-and 4-legged paths) were included in the model calculations.…”

Section: Trlfs Measurementsmentioning

confidence: 99%

Uranyl(VI) complexes with alpha-substituted carboxylic acids in aqueous solution

Moll¹,

Geipel²,

Reich³

et al. 2003

Radiochimica Acta

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The complex formation in the binary uranium(VI)-glycolate, -α-hydoxyisobutyrate, -α-aminoisobutyrate systems in 1.0 M NaClO 4 medium was studied by means of UV-vis, TRLFS, and EXAFS. An increase in absorption and a red shift of the spectra, 5 nm compared to the free UO 2 2+ , indicate a complex formation between UO 2 2+ and α-substituted carboxylic acids already at pH 2. 1 : 1 complexes dominate the uranyl speciation in the glycolate, α-hydoxyisobutyrate, and α-aminoisobutyrate system at pH 2 and 3, respectively. At higher ligand concentrations a 1 : 2 complex between UO 2 2+ and α-aminoisobutyric acid was observed.There is a very strong quenching of the U(VI) fluorescence in the uranyl-α-hydroxycarboxylate systems that can be quantitatively described by the Stern-Volmer equation. As a result of the strong quenching it is not possible to detect fluorescence spectra for these complexes using TRLFS. The UO 2 2+ (aq) concentration calculated from the Stern-Volmer equation was used to determine equilibrium constants which are in good agreement with those obtained by potentiometry and NMR spectroscopy. No quenching was observed in the α-aminoisobutyrate system and their fluorescence spectra could be deconvoluted into components for the different species present. The following stability constants result from our TRLFS experiments: a) for the glycolate system log β UO 2 (HOCH 2 COO) + = 2.52 ± 0.20, b) for the α-hydroxyisobutyrate system log β UO 2 [HOC(CH 3 ) 2 COO] + = 3.40 ± 0.21, and c) for the α-aminoisobutyrate system log β UO 2 [NH 3 C(CH 3 ) 2 COO] 2+ = 1.30 ± 0.10 and log β UO 2 [NH 3 C(CH 3 ) 2 COO] 2 2+ = 2.07 ± 0.25. An increase of the fluorescence intensity connected with a red shift of the fluorescence emission spectra was observed in the system uranyl-α-aminoisobutyric acid. Fluorescence lifetimes and spectra were obtained for UO 2 2+ , UO 2 [NH 3 C(CH 3 ) 2 COO] 2+ , and UO 2 [NH 3 C(CH 3 ) 2 COO] 2 2+ . Uranium L III -edge EXAFS measurements yielded an U−O eq distance of 2.40 to 2.43 Å in the pH range from 2 to 4 in the α-hydroxyisobutyrate system showing a dominant bidentate coordination via the oxygens of the carboxylic group. Slightly shorter U−O eq distances of 2.40 to 2.38 Å and no evidence for U−C distances around 2.90 Å in the glycolate system in this pH range may indicate a monodentate coordinated ligand via one oxygen from the carboxylic group. The decrease in the U−O eq distance of the equatorial oxygens in both systems to pH values ≥ 5 is a strong indication for the formation of a chelate complex due to the deprotonation of the α-OH-group of the ligand. In the glycolate system in the pH range 5.5 to 11, the EXAFS spectrum showed evidence of U−U interaction at 3.81 Å indicating the formation of dimeric species.

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“…The corresponding CϪC, CϪO and CϪH distances in the ligands are reasonable and not significantly different from one another. The core of the structure is a centrosymmetric dimer complex with two metal ions connected by two bridging deprotonated oxy groups, an arrangement also found in a uranyl-glycolate complex [2]. This compound has the same type of monoclinic crystal structure as found previously for Er [5] and contains a deprotonated glycolate ligand.…”

Section: X-ray Structure Determinationmentioning

confidence: 59%

“…The lanthanide glycolate complexes [Ln(HOCH 2 COO) 2 4 ] for the late lanthanide Lu 3ϩ gave needle-like monomer crystals. We made several unsuccessful attempts to promote the dimer formation by adding NaOH to the mother liquor.…”

Section: Preparationmentioning

confidence: 99%

Crystal Structure of two Lanthanide(III) Glycolate Complexes, [Lu(HOCH2COO)2(H2O)4][Lu(HOCH2COO)4] and Dy2(OCH2COO)2(HOCH2COO)2 · 4H2O. An X-Ray Diffraction and Vibrational Spectroscopic Study

Farkas

Fischer

Lindsjö

2002

Z. anorg. allg. Chem.

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The crystal structure of [Lu(HOCH 2 COO) 2 (H 2 O) 4 ]-[Lu(HOCH 2 COO) 4 ] (1) and Dy 2 (OCH 2 COO) 2 (HOCH 2 COO) 2 · 4H 2 O (2) were determined by X-ray crystallography. The space group of 1 and 2 are P2/c and P2 1 /c, respectively. In 1, discrete anions and cations held together by hydrogen bonds form the lattice, while the structure of 2 is a 3-D network of cross-linked metalligand chains. The lanthanides are eight-coordinated by chelating glycolate ligands and water molecules with distorted dodecahedral 2 O (2) wurden mit Einkristall-Röntgenbeugung bestimmt. Die Struktur von 1 besteht aus diskreten Anionen und Kationen, die durch H-Brücken verbunden sind. Die Struktur von 2 besteht aus einem dreidimensionalen Netzwerk von miteinander verbundenen Metall-Liganden-Ketten. Die Lanthanoid-Ionen sind von chelatisierenden Glykolatliganden und Wassermolekülen achtfach koordi-

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Crystal Structure of the Sodium Salt of the Uranyl--Oxyacetate--Fluoride Dimer, Na4(UO2)2(OCH2COO)2F4.6H2O.

Cited by 8 publications

References 0 publications

Complexation of Th(iv) and various lanthanides(iii) by glycolic acid; potentiometric,¹³C-NMR and EXAFS studies

Complexation of Th(iv) and various lanthanides(iii) by glycolic acid; potentiometric,¹³C-NMR and EXAFS studies

Uranyl(VI) complexes with alpha-substituted carboxylic acids in aqueous solution

Crystal Structure of two Lanthanide(III) Glycolate Complexes, [Lu(HOCH2COO)2(H2O)4][Lu(HOCH2COO)4] and Dy2(OCH2COO)2(HOCH2COO)2 · 4H2O. An X-Ray Diffraction and Vibrational Spectroscopic Study

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Crystal Structure of the Sodium Salt of the Uranyl--Oxyacetate--Fluoride Dimer, Na4(UO2)2(OCH2COO)2F4.6H2O.

Cited by 8 publications

References 0 publications

Complexation of Th(iv) and various lanthanides(iii) by glycolic acid; potentiometric,13C-NMR and EXAFS studies

Complexation of Th(iv) and various lanthanides(iii) by glycolic acid; potentiometric,13C-NMR and EXAFS studies

Uranyl(VI) complexes with alpha-substituted carboxylic acids in aqueous solution

Crystal Structure of two Lanthanide(III) Glycolate Complexes, [Lu(HOCH2COO)2(H2O)4][Lu(HOCH2COO)4] and Dy2(OCH2COO)2(HOCH2COO)2 · 4H2O. An X-Ray Diffraction and Vibrational Spectroscopic Study

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Complexation of Th(iv) and various lanthanides(iii) by glycolic acid; potentiometric,¹³C-NMR and EXAFS studies

Complexation of Th(iv) and various lanthanides(iii) by glycolic acid; potentiometric,¹³C-NMR and EXAFS studies