Uranium(III) chloride

Uranium(III) chloride, UCl3, is a water soluble salt of uranium. UCl3 is used mostly to reprocess spent nuclear fuel. Uranium(III) chloride is synthesized in various ways from uranium(IV) chloride; however, UCl3 is less stable than UCl4.

Uranium(III) chloride
Names
IUPAC name
Uranium(III) chloride
Other names
Uranium chloride
Uranium trichloride
Hypouranous chloride
Identifiers
3D model (JSmol)
ChemSpider
UNII
  • InChI=1S/3ClH.U/h3*1H;/q;;;+3/p-3 checkY
    Key: SAWLVFKYPSYVBL-UHFFFAOYSA-K checkY
  • InChI=1/3ClH.U/h3*1H;/q;;;+3/p-3
    Key: SAWLVFKYPSYVBL-DFZHHIFOAG
  • Cl[U](Cl)Cl
Properties
UCl3
Appearance Green crystalline solid
Density 5.500 g/cm3, liquid
Melting point 837 °C (1,539 °F; 1,110 K)
Boiling point 1,657 °C (3,015 °F; 1,930 K)
Soluble
Structure
Hybridisation Tricapped trigonal prismatic
Hazards
Flash point Non-flammable
Non-flammable
Related compounds
Related compounds
 Uranium(IV) chloride,
Uranium(V) chloride,
Uranium(VI) chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Preparation

There are two ways to synthesize uranium(III) chloride. The following processes describe how to produce uranium(III) chloride.

(1) In a mixture of NaCl-KCl at 670–710 °C, add uranium tetrachloride with uranium metal.

3UCl4 + U → 4UCl3[1]

(2) Heat uranium(IV) chloride in hydrogen gas.

2UCl4 + H2 → 2UCl3 + 2HCl[2]

Properties

In solid uranium(III) chloride each uranium atom has nine chlorine atoms as near neighbours, at approximately the same distance, in a tricapped trigonal prismatic configuration.[3]

Uranium(III) chloride is a green crystalline solid at room temperature. UCl3 melts at 837 °C and boils at 1657 °C. Uranium(III) chloride has a density of 5500 kg/m3 or 5.500 g/cm3.

Its composition by weight:

Chlorine: 30.84%
Uranium: 69.16%

Its formal oxidative states:

Chlorine: −1
Uranium: +3

This salt is very soluble in water and is also very hygroscopic. UCl3 is more stable in a solution of hydrochloric acid.[4]

Uses

Reagent

Uranium(III) chloride is used in reactions with tetrahydrofuran (THF) and sodium methylcyclopentadiene to prepare various uranium metallocene complexes.[5]

Catalyst

Uranium(III) chloride is used as a catalyst during reactions between lithium aluminium hydride (LiAlH4) and olefins to produce alkyl aluminate compounds.[6]

Molten form

The molten form of uranium(III) chloride is a typical compound in pyrochemical processes as it is important in the reprocessing of spent nuclear fuels.[7] UCl3 is usually the form that uranium takes as spent fuel in electrorefining processes.[7][8]

Hydrates

There are three hydrates of uranium(III) chloride:

  1. UCl3.2H2O.2CH3CN
  2. UCl3.6H2O
  3. UCl3.7H2O

Each are synthesized by the reduction of uranium(IV) chloride in methylcyanide (acetonitrile), with specific amounts of water and propionic acid.[9]

Precautions

While there are no long-term data on the toxic effects thas UCl3, it is important to minimize exposure to this compound when possible.

Similar to other uranium compounds that are soluble, UCl3 is likely absorbed into the blood through the alveolar pockets of the lungs within days of exposure. Exposure to uranium(III) chloride leads to toxicity of the renal system.[10]

Wikimedia Commons has media related to uranium(III) chloride.

References
  1. Serrano, K.; Taxil, P.; Dugne, O.; Bouvet, S.; Puech, E. J. Nucl. Mater. 2000, 282, 137–145.
  2. Remsen, Ira. Inorganic Chemistry. New York: Henry Holt and Company, 1890.
  3. Wells A.F. (1984) Structural Inorganic Chemistry 5th edition Oxford Science Publications ISBN 0-19-855370-6
  4. Comey, Arthur M.; Hahn, Dorothy A. A Dictionary of Chemical Solubilities: Inorganic. New York: The MacMillan Company, 1921.
  5. Brenna, J.G.; Anderson, R.A.; Zalkin, A. Inorg. Chem. 1986, 25, 1756–1760.
  6. Le Marechal, J.F.; Ephritikhine, M.; Folcher, G. J. Organomet. Chem. 1986, 309, C1–C3.
  7. Okamoto, Y.; Madden, P.; Minato, K. J. Nucl. Mater. 2005, 344, 109–114.
  8. Okamoto, Y.; Kobayashi, F.; Ogawa, T. J. Alloys Compd. 1998, 271, 355–358.
  9. Mech, A.; Karbowick, M.; Lis, T. Polyhedron. 2006, 25, 2083–2092.
  10. Bertell, Rosalie. "Gulf War Veterans and Depleted Uranium." May 1999. Available: http://ccnr.org/du_hague.html
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