Tungsten(IV) iodide

Tungsten(IV) iodide is a binary inorganic compound of tungsten metal and iodine with the chemical formula WI4.

Preparation
Reaction of tungsten(VI) chloride with hydrochloric acid:


 * WCl6 + 6HI -> WI4 + 6HCl + I2

Reaction of tungsten(IV) chloride with hydrochloric acid:
 * WCl4 + 4HI -> WI4 + 4HCl

Physical properties
Tungsten(IV) iodide forms black crystals of the triclinic crystal system. Insoluble in cold water, diethyl ether, and chloroform. It dissolves in ethanol.

Chemical properties
The compound decomposes when heated in vacuum:
 * WI4 -> WI2 + I2

It hydrolyzes in hot water:
 * WI4 + 2H2O -> WO2 + 4HI

Reacts with chlorine and bromine:
 * WI4 + 2Cl2 -> WCl4 + 2I2
 * WI4 + 2Br2 -> WBr4 + 2I2