Thorium(IV) chloride

Thorium(IV) chloride describes a family of inorganic compounds with the formula ThCl4(H2O)n. Both the anhydrous and tetrahydrate (n = 4) forms are known. They are hygroscopic, water-soluble white salts.

Thorium(IV) chloride
Thorium(IV) chloride structure
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.030.039
EC Number
  • 233-056-1
RTECS number
  • XO6475000
UNII
  • InChI=1S/4ClH.Th/h4*1H;/q;;;;+4/p-4
    Key: WEQHQGJDZLDFID-UHFFFAOYSA-J
  • Cl[Th](Cl)(Cl)Cl
Properties
ThCl4
Molar mass 373.849 g/mol
Appearance white needles
hygroscopic
Density 4.59 g/cm3, solid
Melting point 770 °C (1,420 °F; 1,040 K)
Boiling point 921 °C (1,690 °F; 1,194 K)
Structure
tetragonal
Hazards
Lethal dose or concentration (LD, LC):
332 mg/kg intraperitoneal mouse
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

Structures
Alternative view of the structure of solid ThCl4.

The structure of thorium(IV) chloride features 8-coordinate Th centers with doubly bridging chloride ligands.[1]

Synthesis

ThCl4 was an intermediate in the original isolation of thorium metal by Jons Jacob Berzelius.[2]

Thorium(IV) chloride can be produced in a variety of ways. One method is a carbothermic reaction, 700 °C to 2600 °C, involving thorium oxides and carbon in a stream of chlorine gas:

ThO2 + 2 C + 4 Cl2 → ThCl4 + 2 CO

The chlorination reaction can be effected with carbon tetrachloride:[3][4]

Th(C2O4)2 + CCl4 → ThCl4 + 3 CO + 3 CO2

In another two-step method, thorium metal reacts with ammonium chloride:

Th + 6 NH4Cl → (NH4)2ThCl6 + 4 NH3 + 2 H2

The hexachloride salt is then heated at 350 °C under a high vacuum to produce ThCl4.[5]

Reactions
Lewis base adducts

ThCl4 reacts with Lewis bases to give molecular adducts, such as ThCl4(DME)2 and ThCl4(TMEDA)2.[5]

Reduction to Th metal

Thorium(IV) chloride is an intermediate in the purification of thorium, which can be affected by:

  1. Reduction of ThCl4 with alkali metals.
  2. Electrolysis of anhydrous thorium(IV) chloride in fused mixture of NaCl and KCl.
  3. Ca reduction of a mixture of ThCl4 with anhydrous zinc chloride.[6]

References
  1. Mason, J. T.; Jha, M. C.; Chiotti, P. (1974). "Crystal Structures of ThCl4 Polymorphs". Journal of the Less Common Metals. 34: 143–151. doi:10.1016/0022-5088(74)90224-0.
  2. Weeks, Mary Elvira (1932-07-01). "The Discovery of the Elements. XI. Some Elements Isolated with the Aid of Potassium and Sodium: Zirconium, Titanium, Cerium, and Thorium". Journal of Chemical Education. 9 (7): 1231. Bibcode:1932JChEd...9.1231W. doi:10.1021/ed009p1231. ISSN 0021-9584.
  3. Brauer, Georg (1963). Handbook Of Preparative Inorganic Chemistry. New York: Academic Press.
  4. Gutierrez, R. L.; Herbst, R. J. (October 1979). "Preliminary Fabrication Studies of Alternative LMFBR Carbide Fuels". Los Alamos Scientific Laboratory. doi:10.2172/5688597.
  5. Cantat, Thibault; Scott, Brian L.; Kiplinger, Jaqueline L. (2010-01-25). "Convenient Access to the Anhydrous Thorium Tetrachloride Complexes ThCl4(DME)2, ThCl4(1,4-dioxane)2 and ThCl4(THF)3.5 using Commercially Available and Inexpensive Starting Materials". Chemical Communications. 46 (6): 919–21. doi:10.1039/b923558b. ISSN 1364-548X. PMID 20107650.
  6. "Periodic Table of Elements: Los Alamos National Laboratory". periodic.lanl.gov. Retrieved 2016-04-29.


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