Tungsten(IV) oxide is the chemical compound with the formula . The bronze-colored solid crystallizes in a monoclinic cell. The rutile-like structure features distorted octahedral centers with alternate short W–W bonds (248 pm). Each tungsten center has the d2 configuration, which gives the material a high electrical conductivity.
is prepared by reduction of with tungsten powder over the course of 40 hours at 900 °C. An intermediate in this reaction is the partially reduced, mixed valence species .
The molybdenum analogue is prepared similarly. Single crystals are obtained by chemical transport technique using iodine. Iodine transports the in the form of the volatile species .
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