Tungsten pentafluoride  Tungsten(V) fluoride is an inorganic compound with the formula WF5. It is a hygroscopic yellow solid. Like most pentafluorides, it adopts a tetrameric structure, consisting of [WF5]4 molecules. In this way, each W center achieves octahedral coordination. Tungsten(V) fluoride is produced by the reaction of tungsten and tungsten hexafluoride:  At room temperature, it disproportionates to the tetra- and hexafluoride: