ISSN:
0044-2313
Keywords:
Rare earths oxochlorouranates(VI) Ln3UO6Cl3 (Ln=La, Pr, Nd)
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preparation
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chemical transport
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X-ray single crystal structure refinement
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high resolution electron microscopy investigation
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Chemistry
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Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Description / Table of Contents:
Ln3UO6Cl3 (Ln=La, Pr, Nd) - The First Oxochlorouranates of the Rare Earths.The new compounds Ln3UO6Cl3 (Ln=La, Pr, Nd) were prepared by heating stoichiometric amounts of LnOCl/Ln2O3/U3O8 (7 : 1 : 1) (Ln=La, Nd) and PrOCl/Pr6O11/U3O8 (12 : 1 : 2) in silica ampoules (5 d, 1000°C, Ln=La; 9 d 800°C, Ln=Pr, Nd) in the presence of an excess of chlorine [p(Cl2, 25°C)=1 atm]. Single crystals were obtained by chemical transport reactions using chlorine [p(Cl2, 25°C)=1 atm] as transport agent [T2=1000°C→T1=900°C (Ln=La); T2=840°C→T1=780°C (Ln=Pr, Nd)].Crystals of Ln3UO6Cl3 (Ln=La, Pr, Nd) were investigated by X-ray diffraction methods and La3UO6Cl3 additionally by high resolution electron microscopy.The compounds Ln3UO6Cl3 crystallize in the hexagonal spacegroup P63/m (No. 176) with Z=2 formula units per unit cell. Isotypical structure refinements resulted in R=3.04% respectively Rw=1.91% (Ln=La), R=4.72% respectively Rw=3.80% (Ln=Pr) and R=3.99% respectively Rw=2.49% (Ln=Nd). Uranium is coordinated with six oxygen atoms forming a trigonal prism. Lanthanide ions are 10-coordinated (6 oxygen atoms, 4 chlorine atoms).
Notes:
Die neuen Verbindungen Ln3UO6Cl3 (Ln=La, Pr, Nd) entstehen bei der Umsetzung von Gemengen LnOCl/Ln2O3/U3O8 (7 : 1 : 1) (Ln=La, Nd) und PrOCl/Pr6O11/U3O8 (12 : 1 : 2) mit überschüssigem Chlor in Quarzglasampullen (5 d, 1000°C, Ln=La; 9 d, 800°C, Ln=Pr, Nd). Durch chemischen Transport der Oxochlorouranate mit Chlor [p(Cl2, 25°C)=1 atm; T2=1000°C→T1=900°C (Ln=La) und T2=840°C→T1=780°C (Ln=Pr, Nd)] zugängliche Einkristalle wurden röntgenographisch (Ln=La, Pr, Nd) und elektronenmikroskopisch (Ln=La) untersucht.Die Verbindungen Ln3UO6Cl3 kristallisieren hexagonal in der Raumgruppe P63/m (Nr. 176) mit Z=2 Formeleinheiten pro Elementarzelle. Die mit La3WO6Cl3 isotypen Strukturen wurden bis zu R=3,04% bzw. Rw=1,91% (Ln=La), R=4,72% bzw. Rw=3,80% (Ln=Pr) und R=3,99% bzw. 2,49% (Ln=Nd) verfeinert. Uran ist trigonal prismatisch von Sauerstoffatomen umgeben. Die Koordinationszahl der Seltenerdionen ist 10 (6 Sauerstoff-, 4 Chloratome).
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/zaac.19936190113
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