Thorium triiodide

Thorium triiodide is a binary inorganic compound of thorium metal and iodine with the chemical formula ThI₃.^[1][2][3]

Thorium triiodide

Identifiers
CAS Number	13779-96-9
3D model (JSmol)	Interactive image
PubChem CID	175754991 (charge error)
InChI InChI=1S/3HI.Th/h3*1H;/q;;;+3/p-3 Key: DSHBAXKNFMWFAR-UHFFFAOYSA-K
SMILES [Th+3].[I-].[I-].[I-]
Properties
Chemical formula	I3Th
Molar mass	612.7511 g·mol−1
Appearance	crystals
Solubility in water	reacts with water
Related compounds
Related compounds	Americium triiodide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Synthesis

Th metal is heated with ThI₄ in a vacuum at 800 °C.^[4]

Th + 3ThI₄ → 4ThI₃

Physical properties

Thorium triiodide is a black, violet-tinged, usually poorly crystallized mass. Formed crystals exhibit strong dichroism from violet to olive green under the microscope and are birefringent.^[5] Above 550 °C, thorium(III) iodide decomposes to thorium(IV) iodide and thorium(II) iodide. β-thorium(III) iodide has an orthorhombic crystal structure with the space group Cccm (space group no. 66).^[6] The α-form has a pseudoorthorhombic crystal structure.

Chemical properties

ThI₃ reacts with water to form thorium tetraiodide and thorium metal.^[4]