Tungsten(IV) oxide

Tungsten(IV) oxide
Other names

Tungsten dioxide
Identifiers
CAS number 12036-22-5 Y
Properties
Molecular formula WO2
Molar mass 215.84 g/mol
Appearance bronze solid
Density 10.8 g/cm3
Melting point

1700 °C decomp.
Solubility in water insoluble
Magnetic susceptibility 5.7×10−5 cm3/mol
Structure
Crystal structure Distorted rutile, (monoclinic), mP12, Space group P21/c, No 14
Hazards
EU Index Not listed
Flash point Non-flammable
Related compounds
Other anions Tungsten disulfide
Other cations Chromium(IV) oxide
Molybdenum(IV) oxide
Related tungsten oxides Tungsten(III) oxide
Tungsten(VI) oxide
 Y (verify) (what is: Y/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Tungsten dioxide is the chemical compound with the formula WO2. The bronze-colored solid crystallizes in a monoclinic cell.[1] The rutile-like structure features distorted octahedral WO6 centers with alternate short W–W bonds (248 pm).[1] Each tungsten center has the d2 configuration, which gives the material a high electrical conductivity.

WO2 is prepared by reduction of WO3 with tungsten powder over the course of 40 hours at 900 °C. An intermediate in this reaction is the partially reduced, mixed valence species W18O49.

2 WO3 + W → 3 WO2

The molybdenum analogue MoO2 is prepared similarly. Single crystals are obtained by chemical transport technique using iodine. Iodine transports the WO2 in the form of the volatile species WO2I2.[2]

References

  1. ^ a b Wells, A. F. (1984), Structural Inorganic Chemistry (5th ed.), Oxford: Clarendon Press, ISBN 0-19-855370-6 
  2. ^ Conroy, L. E.; Ben-Dor, L. (1995), "Molybdenum(IV) Oxide and Tungsten(IV) Oxides Single-Crystals", Inorg. Synth., Inorganic Syntheses 30: 105–07, doi:10.1002/9780470132616.ch21, ISBN 0-471-30508-1