Chemical compound

Tungsten(IV) oxide 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][3]

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". Inorganic Syntheses. 30: 105–07. doi:10.1002/9780470132616.ch21. ISBN 9780470132616.
  3. ^ Rogers, D. B.; Butler, S. R.; Shannon, R. D. (1972). "Single Crystals of Transition-Metal Dioxides". Inorganic Syntheses. XIII: 135–145. doi:10.1002/9780470132449.ch27. ISBN 9780470132449.