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Uranium(VI) chloride

Uranium hexachloride
Uranium Hexachloride.png
Names
IUPAC name
Uranium(VI) chloride
Other names
Uranium hexachloride
Peruranic chloride
Identifiers
Properties
UCl6
Molar mass 450.745 g/mol
Appearance dark green crystalline solid
Density 3600 kg/m3
Melting point 177 °C (351 °F; 450 K)
Boiling point 75 °C (167 °F; 348 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Uranium hexachloride is an inorganic chemical compound of uranium in the +6 oxidation state. The chemical compound Uranium hexachloride (UCl6) is a metal halide composed of Uranium and Chlorine. It is a multi-luminescent dark green crystalline solid with a vapor pressure between 1-3 mmHg at 373.15K UCl6 is stable in a vacuum, dry air, nitrogen and helium at room temperature. It is soluble in carbon tetrachloride (CCl4). Compared to the other uranium halides, little is known about UCl6.

Uranium hexachloride has an octahedral geometry with a point group of Oh. Its lattice (dimensions: 10.95 ± 0.02Å x 6.03 ± 0.01Å) is hexagon in shape with three molecules per cell; the average theoretical U-Cl bond is 2.472Å long (X-ray diffraction experimental U-Cl length is 2.42Å) and the distance between two adjacent chlorine atoms is 3.65Å .

Uranium hexachloride is a highly hygroscopic compound and decomposes readily when exposed to ordinary atmospheric conditions. therefore it should be handled in either a vacuum apparatus or in a dry box.

UCl6 is stable up to temperatures between 120oC and 150oC. The decomposition of UCl6 results in a solid phase transition from one crystal form of UCl6 to another more stable form. However the decomposition of gaseous UCl6 produces (UCl5). The Activation energy for this reaction is about 40kcal per mole.


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