Tungsten(IV) oxide
| Tungsten(IV) oxide | |
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Other names
Tungsten dioxide |
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| Identifiers | |
| CAS number | 12036-22-5  |
| PubChem | 82850 |
| EC number | 234-832-7 |
| Jmol-3D images | Image 1 |
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| Properties | |
| Molecular formula | WO2 |
| Molar mass | 215.839 g/mol |
| Appearance | bronze solid |
| Density | 10.8 g/cm3 |
| Melting point |
1700 °C decomp. |
| Solubility in water | negligible |
| 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 |
 (verify) (what is:  / ?)Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| 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]
[edit] References
- ^ a b Wells, A. F. (1984), Structural Inorganic Chemistry (5th ed.), Oxford: Clarendon Press, ISBN 0-19-855370-6
- ^ 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
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