Tungsten(II) iodide

Tungsten(II) iodide is an iodide of tungsten, with the chemical formula [W₆I₈]I₄, or abbreviated as WI₂.

Tungsten(II) iodide

Identifiers
CAS Number	13470-17-2 Y
3D model (JSmol)	Interactive image
ChemSpider	464830
PubChem CID	533504
InChI InChI=1S/2HI.W/h2*1H;/q;;+2/p-2 Key: BMKSRUJKNOBSHP-UHFFFAOYSA-L
SMILES [I-].[I-].[W+2]
Properties
Chemical formula	I2W
Molar mass	437.65 g·mol−1
Appearance	dark brown solid[1]
Density	6.79 g·cm−3[2]
Melting point	800 °C (decomposes)[2]
Solubility in water	insoluble[2]
Related compounds
Other anions	tungsten(II) chloride tungsten(II) bromide
Other cations	chromium(II) iodide molybdenum(II) iodide
Related compounds	tungsten(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

Tungsten diiodide can obtained from the decomposition from tungsten(III) iodide:^[1]

6 WI₃ → [W₆I₈]I₄ + 3 I₂

It can also be formed by the displacement reaction of tungsten(II) chloride and iodine:^[1]

[W₆Cl₈]Cl₄ + 12 I → [W₆I₈]I₄ + 12 Cl

It can also be formed by the direct reaction of tungsten and iodine, which is a reversible reaction. This reaction can be used in halogen lamps.^[3]

W + I₂ ⇌ WI₂

Tungsten(II) iodide can also be obtained by reacting tungsten hexacarbonyl with iodine.^[4]

Properties

Tungsten(II) iodide is a dark brown-colored solid that is stable in air and moisture. Its structure is the same as tungsten(II) chloride, crystallising orthorhombic crystal system, with space group Bbem (No. 64), and lattice parameters a = 1258 pm, b = 1259 pm, c = 1584 pm.^[1]