Tungsten(IV) oxide

Tungsten(IV) oxide

Chembox new
ImageFile = Tungsten(IV)_oxide.jpg
ImageName = Tungsten(IV) oxide
OtherNames = Tungsten dioxide
Section1 = Chembox Identifiers
CASNo = 12036-22-5
Section2 = Chembox Properties
Formula = O2W
MolarMass = 215.84 g/mol
Appearance = bronze solid
Density = 10.8 g/cm³, solid
MeltingPt = 1700 °C (decomposes)
Solubility = Insoluble
Section3 = Chembox Structure
CrystalStruct = monoclinic
Section7 = Chembox Hazards
EUClass = not listed

Tungsten dioxide is the chemical compound with the formula WO2. The bronze-colored solid crystallizes in a monoclinic cell. Wells A.F. (1984) "Structural Inorganic Chemistry" 5th edition Oxford Science Publications ISBN 0-19-855370-6 ] The rutile-like structure features distorted octahedral WO6 centers with alternate short W-W bonds (248 pm). Each W center has the "d"2 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 WO2The 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. [Conroy, L. E.; Ben-Dor, L. "Molybdenum(IV) Oxide and Tungsten(IV) Oxides Single-Crystals" Inorganic Syntheses 1995, volume 30, pp. 105-107. ISBN 0-471-30508-1]

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