Uranium hexachloride

Source: Wikipedia, the free encyclopedia.
Uranium hexachloride
Names
IUPAC name
Uranium(VI) chloride
Other names
Uranium hexachloride
Peruranic chloride
Identifiers
3D model (
JSmol
)
ChemSpider
  • InChI=1S/6ClH.U/h6*1H;/p-6
    Key: XFCORTPUZRSUIZ-UHFFFAOYSA-H
  • [Cl-].[Cl-].[Cl-].[Cl-].[Cl-].[Cl-].[U]
Properties
UCl6
Molar mass 450.745 g/mol
Appearance dark green crystalline solid
Density 3.6 g/cm3
Melting point 177 °C (351 °F; 450 K)
Related compounds
Other anions
 Uranium hexafluoride
Other cations
 Tungsten hexachloride
Related uranium chlorides
  • Uranium(V) chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Uranium hexachloride (UCl6) is an

inorganic chemical compound of uranium in the +6 oxidation state.[1][2] 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 373.15 K.[3] 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.

Structure and Bonding

Uranium hexachloride has an

X-ray diffraction is 2.42 Å),[4]
and the distance between two adjacent chlorine atoms is 3.65 Å.

Chemical properties

Uranium hexachloride is a highly

hygroscopic compound and decomposes readily when exposed to ordinary atmospheric conditions.[5]
therefore it should be handled in either a vacuum apparatus or in a dry box.

Thermal decomposition

UCl6 is stable up to temperatures between 120 °C and 150 °C. The

gaseous UCl6 produces UCl5. The activation energy for this reaction is about 40 kcal per mole
.

2 UCl6 (g) → 2 UCl5 (s) + Cl2 (g)

Solubility

UCl6 is not a very

soluble compound. It dissolves in CCl4 to give a brown solution. It is slightly soluble in isobutyl bromide and in fluorocarbon (C7F16).[6]

Solvents Temperature (°C) Grams of UCl6/100g of solution
CCl4 −18 2.64
CCl4 0 4.9
CCl4 20 7.8
6.6% Cl2 : 93.4% CCl4 −20 2.4
12.5% Cl2 : 87.5% CCl4 −20 2.23
12.5% Cl2 : 87.5% CCl4 0 3.98
Liquid Cl2 −33 2.20
CH3Cl −24 1.16
Benzene 80
Insoluble
Freon 113
 45 1.83

Reaction with hydrogen fluoride

When UCl6 is reacted with purified anhydrous liquid hydrogen fluoride (HF) at room temperature produces UF5.[6]

2 UCl6 + 10 HF → 2 UF5 + 10 HCl + Cl2

Synthesis

Uranium hexachloride can be synthesized from the reaction of

reactant (ideal temperature 100 °C - 125 °C). The reaction is carried out in a closed gas-tight vessel (for example a glovebox
) that can withstand the pressure that builds up.

Step 1: 2 UO3 + 5 Cl2 → 2 UCl5 + 3 O2

Step 2: 2 UCl5 + Cl2 → 2 UCl6

Overall reaction: 2 UO3 + 6 Cl2 → 2 UCl6 + 3 O2

This metal hexahalide can also be synthesized by blowing Cl2 gas over sublimed UCl4 at 350 °C.[8]

Step 1: 2 UCl4 + Cl2 → 2 UCl5

Step 2: 2 UCl5 + Cl2 → 2 UCl6

Overall Reaction: UCl4 + Cl2 → UCl6

References

  1. doi:10.1107/S0365110X48000788
    .
  2. doi:10.1107/S0567740874005115
    .
  3. ^ Van Dyke, R. E.; Evers, E. C. (1955). "Preparation of Uranium Hexachloride". Google Patents: 2.
  4. PMID 15634063
    .
  5. ^ Lipkin, D.; Wessman, S. (1955). "Process and Apparatus for protecting Uranium hexachloride from Deterioration and Contamination". Google Patents: 2.
  6. ^ a b c Katz, J.J.; Rabinowitch,E. (1951). The Chemistry of Uranium. Ann Arbor: The McGraw-Hill Book Company.
  7. ^ Van Dyke, R. E.; Evers, E. C. (1955). "Preparation of Uranium Hexachloride". Google Patents: 2.
  8. doi:10.1063/1.437313
    .
Retrieved from "https://en.wikipedia.org/w/index.php?title=Uranium_hexachloride&oldid=1217539500"