Tungsten hexachloride
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| Names | |||
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| IUPAC names
Tungsten hexachloride Tungsten(VI) chloride | |||
| Identifiers | |||
13283-01-7  | |||
| EC Number | 236-293-9 | ||
| Jmol 3D image | Interactive graph | ||
| PubChem | 83301 | ||
| RTECS number | YO7710000 | ||
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| Properties | |||
| WCl6 | |||
| Molar mass | 396.61 g/mol | ||
| Appearance | dark blue crystals, moisture sensitive | ||
| Density | 3.52 g/cm3 | ||
| Melting point | 275 °C (527 °F; 548 K) | ||
| Boiling point | 346.7 °C (656.1 °F; 619.8 K) | ||
| hydrolyzes | |||
| Solubility in chlorocarbons | soluble | ||
| Structure | |||
| α:rhombohedral, β: hexagonal | |||
| octahedral | |||
| 0 D | |||
| Hazards | |||
| Main hazards | oxidizer; hydrolysis releases HCl | ||
| Related compounds | |||
| Other anions |
Tungsten hexafluoride Tungsten hexabromide | ||
| Other cations |
Molybdenum(V) chloride Chromyl chloride | ||
| Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |||
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| 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.
Preparation
Tungsten hexachloride can be prepared by chlorinating tungsten metal in a sealed tube at 600°C: [3]
- W + 3 Cl2 → WCl6
Properties and Reactions
Tungsten (VI) chloride is a blue-black crystalline solid at room temperature. At lower temperatures, it becomes wine-red in color. A red form of the compound can be made by rapidly condensing its vapor, which reverts to the blue-black form on gentle heating. It is readily hydrolyzed in moist air, giving the orange oxychlorides WOCl4 & WO2Cl2, and subsequently, tungsten trioxide. WCl6 is soluble in carbon disulfide, carbon tetrachloride and phosphorus oxychloride.[3]
Methylation with trimethylaluminium affords hexamethyl tungsten:
- WCl6 +3 Al2(CH3)6 → W(CH3)6 + 3 Al2(CH3)4Cl2
Treatment with butyl lithium affords a reagent that is useful for deoxygenation of epoxides.[4]
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
- ↑ 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.
- ↑ 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.
- 1 2 Ludwig F. Audrieth (2007). Inorganic Syntheses. McGraw-Hill Book Company. p. 165. ISBN 9780470131626.
- ↑ M. A. Umbreit, K. B. Sharpless (1990). "Deoxygenation of Epoxides with Lower Valent Tungsten Halides: trans-Cyclododecene". Org. Synth.; Coll. Vol. 7, p. 121
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