Tungsten hexachloride

Tungsten hexachloride
Identifiers
CAS number 13283-01-7 Y
PubChem 83301
RTECS number YO7710000
Properties
Molecular formula WCl6
Molar mass 396.61 g/mol
Appearance dark blue crystals, moisture sensitive
Density 3.52 g/cm3
Melting point

275 °C

Boiling point

346.7 °C

Solubility in water hydrolyzes
Solubility in chlorocarbons soluble
Structure
Crystal structure α:rhombohedral, β: hexagonal
Coordination
geometry
octahedral
Dipole moment 0 D
Hazards
EU Index Not listed
Main hazards oxidizer; hydrolysis releases HCl
Related compounds
Other anions Tungsten hexafluoride
Tungsten hexabromide
Other cations Molybdenum(V) chloride
Chromyl chloride
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Tungsten hexachloride is the chemical compound of tungsten and chlorine 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.[1] WCl6 is a rare example of a charge-neutral hexachloride, another example being ReCl6. Better known than WCl6 is the still more volatile WF6.

As a d0 ion, W(VI) forms diamagnetic derivatives. The hexachloride is octahedral with equivalent W-Cl distances of 2.24 - 2.26 Å.[2] In acceptor, the chloride ligands are donors in both sigma- and pi sense. Methylation with trimethylaluminium affords hexamethyl tungsten. Treatment with butyl lithium affords a reagent that is useful for deoxygenation of epoxides.[3]

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 hydrolyzes to release hydrogen chloride.

References

  1. ^ J. W. Herndon "Tungsten(VI) Chloride” in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. DOI: 10.1002/047084289.
  2. ^ J. C. Taylor and P. W. Wilson "The structure of [beta]-tungsten hexachloride by powder neutron and X-ray diffraction" Acta Crystallographic (1974). B30, 1216-1220.doi:10.1107/S0567740874004572.
  3. ^ M. A. Umbreit, K. B. Sharpless (1990), "Deoxygenation of Epoxides with Lower Valent Tungsten Halides: trans-Cyclododecene", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=CV7P0121 ; Coll. Vol. 7: 121