Tungsten(VI) oxytetrachloride

Tungsten(VI) oxytetrachloride is the inorganic compound with the formula WOCl4. This diamagnetic solid is used to prepare other complexes of tungsten. The red crystalline compound is soluble in nonpolar solvents but it reacts with alcohols and water and forms adducts with Lewis bases.

Structure
The solid consists of weakly associated square pyramidal monomers. The compound is classified as an oxyhalide.

Synthesis and reactions
WOCl4 is prepared from tungsten trioxide:
 * WO3 +  2 SOCl2   →   WOCl4  +  2 SO2
 * WCl6 + (Me3Si)2O →  WOCl4 + 2  Me3SiCl

It is "difficult to prepare by other means."

WOCl4 is Lewis acidic. It is a precursor to catalysts used for polymerization of alkynes.