Cerium diiodide

Cerium diiodide is an iodide of cerium, with the chemical formula of CeI₂.

Cerium diiodide

Identifiers
CAS Number	19139-47-0
3D model (JSmol)	Interactive image
InChI InChI=1S/Ce.2HI/h;2*1H/q+2;;/p-2 Key: ORCLLRHIKXTOMX-UHFFFAOYSA-L
SMILES [I-].[I-].[Ce+2]
Properties
Chemical formula	CeI2
Molar mass	393.925 g·mol−1
Appearance	bronze solid[1]
Melting point	808 °C[1]
Structure
Space group	I4/mmm (No. 139)
Related compounds
Other cations	lanthanum diiodide praseodymium diiodide neodymium(II) iodide
Related compounds	cerium(III) iodide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Preparation

Cerium diiodide can be obtained from the reduction of cerium(III) iodide with metallic cerium under vacuum at 800 °C to 900 °C.^[2]

Ce + 2 CeI₃ → CeI₂

It can also be formed from the reaction of cerium and ammonium iodide in liquid ammonia at −78 °C. The reaction forms an ammonia complex of cerium diiodide, which decomposes to cerium diiodide under vacuum at 200 °C.^[2]

Ce + 2 NH₄I → CeI₂ + 2 NH₃ + H₂

It was first created by John D. Corbett in 1961.^[3]

Properties

Cerium diiodide is an opaque dark solid with a metal-like appearance and properties. There is no cerium(II) in cerium diiodide, and its real structure is Ce³⁺(I⁻)₂e⁻. It is easily hydrolyzed to form the corresponding oxyiodide.^[2] Like lanthanum diiodide and praseodymium diiodide, the cerium diiodide forms in the MoSi₂-type structure,^[4] with space group I4/mmm (No. 139).^[5]