Lanthanum diiodide

Lanthanum diiodide is an iodide of lanthanum, with the chemical formula of LaI₂. It is an electride, actually having a chemical formula of La³⁺[(I⁻)₂e⁻].^[2]

Lanthanum diiodide

Identifiers
CAS Number	19214-98-3
3D model (JSmol)	Interactive image
InChI InChI=1S/La.2HI/h;2*1H/q+2;;/p-2 Key: UYZZZMCZZNTWGP-UHFFFAOYSA-L
SMILES [I-].[I-].[La+2]
Properties
Chemical formula	I2La
Molar mass	392.71441 g·mol−1
Appearance	blue-black solid[1]
Density	5.46 g/cm−3[1]
Melting point	830 °C[1]
Related compounds
Other cations	cerium diiodide praseodymium diiodide
Related compounds	lanthanum(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

Lanthanum diiodide can be obtained from the reduction of lanthanum(III) iodide with lanthanum metal under a vacuum at 800 to 900 °C:^[3]

La + 2 LaI₃ → LaI₂

It can also be obtained by reacting lanthanum and mercury(II) iodide:^[3]

La + HgI₂ → LaI₂ + Hg

It was first created by John D. Corbett in 1961.^[4]

Properties

Lanthanum diiodide is a blue-black solid with metallic lustre, which is easily hydrolyzed into the iodide oxide.^[3] It has a MoSi₂-type structure, with the space group I4/mmm (No. 139).^[5]