Tungsten dichloride dioxide

Tungsten dichloride dioxide is the chemical compound with the formula WO2Cl2. It is a yellow-colored solid. It is used as a precursor to other tungsten compounds. Like other tungsten halides, WO2Cl2 is sensitive to moisture, undergoing hydrolysis.

Tungsten(VI) dioxydichloride
Names
Other names
tungsten(VI) dioxydichloride
Identifiers
3D model (JSmol)
ECHA InfoCard 100.033.496
EC Number
  • 236-862-1
Properties
WO2Cl2
Molar mass 286.749 g/mol
Appearance yellow-red crystals
Density 4.67 g/cm3, solid
Melting point 265 °C (509 °F; 538 K)
Boiling point sublimes > 350 °C in vacuo
decomposes
Solubility slightly soluble in ethanol
Structure
orthorhombic
Hazards
not listed
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

Preparation

WO2Cl2 is prepared by ligand redistribution reaction from tungsten trioxide and tungsten hexachloride:

2 WO3 + WCl6 → 3 WO2Cl2

Using a two-zone tube furnace, a vacuum-sealed tube containing these solids is heated to 350 °C. The yellow product sublimes to the cooler end of the reaction tube. No redox occurs in this process.[1] An alternative route highlights the oxophilicity of tungsten:[2]

WCl6 + 2 O(Si(CH3)3)2 → 3 WO2Cl2 + 4 ClSi(CH3)3

This reaction, like the preceding one, proceeds via the intermediacy of WOCl4.

Structure

The compound is a polymer consisting of distorted octahedral W centres. The monomer is characterized by two short W-O distances, typical for a multiple W-O bond, and two long W-O distances more typical of a single or dative W-O bond.[3]

Tungsten forms a number of oxyhalides including WOCl4, WOCl3, WOCl2. The corresponding bromides (WOBr4, WOBr3, WOBr2) are also known as is WO2I2.[4]

Structure of the complex WO2Cl2(dimethoxyethane).

Reactions

WO2Cl2 is a Lewis acid, forming soluble adducts of the type WO2Cl2L2, where L is a donor ligand such as bipyridine and dimethoxyethane. Such complexes often cannot be prepared by depolymerization of the inorganic solid, but are generated in situ from WOCl4.[5]

References
  1. Tillack, J. (1973). "Tungsten Oxyhalides". Inorg. Synth. 14: 109–122. doi:10.1002/9780470132456.ch22.
  2. Gibson, V. C.; Kee, T. P.; Shaw, A. (1988). "New, improved synthesis of the group 6 oxyhalides, W(O)Cl4, W(O)2Cl2 and Mo(O)2Cl2". Polyhedron. 7 (7): 579–80. doi:10.1016/S0277-5387(00)86336-6.
  3. Jarchow, O.; Schröder, F.; Schulz, H. "Kristallstruktur und Polytypie von WO2Cl2" Zeitschrift für anorganische und allgemeine Chemie 1968, vol. 363, p. 345ff. doi:10.1002/zaac.19683630108
  4. Holleman, A. F.; Wiberg, E. Inorganic Chemistry Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
  5. K. Dreisch, C. Andersson, C. Stalhandske "Synthesis and structure of dimethoxyethane-dichlorodioxo-tungsten(VI)—a highly soluble derivative of tungsten dioxodichloride" Polyhedron 1991, volume 10, p. 2417. doi:10.1016/S0277-5387(00)86203-8
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