Tungsten(IV) oxide, WO2, is a bronze-colored solid that crystallizes in a monoclinic cell. The rutile-like structure features distorted octahedral WO6 centers with alternate short W-W bonds (248 pm). 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 in about 40 h at 900℃. An intermediate in this reaction is the partially reduced, mixed valence species W18O49.
2WO3 + W→3WO2
brown powder(s), may become purple on standing; formed when WO3 is reduced by H2 at 575°C–600°C [KIR83] [STR93]
Tungsten(IV) oxide is used in the production of tungsten and tungstates, in alloys, in fire-proofing fabrics and as a ceramic pigment. It is used to study their chromism, photocatalysis and sensing capabilities. It is associated with rhenium trioxide particles and used for detection of protonatable, radical and precharged species under laser desorption ionization.
