Tungsten(II) iodide

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

Preparation
Tungsten diiodide can obtained from the decomposition from tungsten(III) iodide:


 * 6 WI3 -> [W6I8]I4 + 3 I2

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


 * [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.


 * W + I2 <-> WI2

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

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.