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
CAS Number	10026-08-1 Y
3D model (JSmol)	Interactive image
ChemSpider	59594
ECHA InfoCard	100.030.039
EC Number	233-056-1
PubChem CID	66209
RTECS number	XO6475000
UNII	24Q3L637MM Y
CompTox Dashboard (EPA)	DTXSID6064905
InChI InChI=1S/4ClH.Th/h4*1H;/q;;;;+4/p-4 Key: WEQHQGJDZLDFID-UHFFFAOYSA-J
SMILES Cl[Th](Cl)(Cl)Cl
Properties
Chemical formula	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
Crystal structure	tetragonal
Hazards
Lethal dose or concentration (LD, LC):
LD50 (median dose)	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). N verify (what is YN ?) 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]