Tungsten hexachloride

Tungsten hexachloride is the chemical compound with the formula WCl6. This dark violet blue species exists as a volatile solid under standard conditions. It is an important starting reagent in the preparation of tungsten compounds. WCl6 is a rare example of a charge neutral hexachloride, since MoCl6 cannot be prepared. Another example is ReCl6. Better known than WCl6 is the still more volatile WF6.

W(VI) is a d0 ion, so its derivatives are diamagnetic. WCl6 and W(CO)6, both octahedral tungsten compound differ dramatically in properties and bonding. In the WCl6, the chloride ligands are donors in both sigma- and pi sense. In contrast, in W(CO)6, the CO ligands are still sigma donor ligands, but they are also pi-acids.

The chloride ligands in WCl6 can be replaced by many anionic ligands including Br-, NCS-, and RO- (R = alkyl, aryl).

Safety considerations
WCl6 is an aggressively corrosive oxidant and readily hydrolyzes to release Hydrogen chloride.