Thorium(IV) chloride


Thorium chloride describes a family of inorganic compounds with the formula ThCl4n. Both the anhydrous and tetrahydrate forms are known. They are hygroscopic, water-soluble white salts.

Structures

[image:Kristallstruktur Uran(IV)-fluorid.png|thumb|left|162px|Alternative view of the structure of solid ThCl4.]
The structure of thorium chloride features 8-coordinate Th centers with doubly bridging chloride ligands.

Synthesis

ThCl4 was an intermediate in the original isolation of thorium metal by Jons Jacob Berzelius.
Thorium 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:
The chlorination reaction can be effected with carbon tetrachloride:
In another two-step method, thorium metal reacts with ammonium chloride:
The hexachloride salt is then heated at 350 °C under a high vacuum to produce ThCl4.

Reactions

;Lewis base adducts
ThCl4 reacts with Lewis bases to give molecular adducts, such as ThCl42 and ThCl42.
;Reduction to Th metal
Thorium 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 chloride in fused mixture of NaCl and KCl.
  3. Ca reduction of a mixture of ThCl4 with anhydrous zinc chloride.