Bismuth pentafluoride is an inorganic compound with the formula BiF<sub>5</sub>. It is a white solid that is highly reactive. The compound is of interest to researchers but not of particular value.
BiF<sub>5</sub> is polymeric and consists of linear chains of trans-bridged corner sharing BiF<sub>6</sub> octahedra. This is the same structure as ñ-UF<sub>5</sub>.
BiF<sub>5</sub> can be prepared by treating BiF<sub>3</sub> with F<sub>2</sub> at 500 ðC.
In an alternative synthesis, ClF<sub>3</sub> is the fluorinating agent at 350 ðC.
Bismuth pentafluoride is the most reactive of the pnictogen pentafluorides and is an extremely strong fluorinating agent. It reacts vigorously with water to form ozone and oxygen difluoride, and with iodine or sulfur at room temperature. BiF<sub>5</sub> fluorinates paraffin oil (hydrocarbons) to fluorocarbons above 50 ðC and oxidises UF<sub>4</sub> to UF<sub>6</sub> at 150 ðC. At 180 ðC, bismuth pentafluoride fluorinates Br<sub>2</sub> to BrF<sub>3</sub> and Cl<sub>2</sub> to ClF.
BiF<sub>5</sub> also reacts with alkali metal fluorides, MF, to form hexafluorobismuthates, M[BiF<sub>6</sub>], containing the hexafluorobismuthate anion, [BiF<sub>6</sub>]<sup>âÂÂ</sup>. Bismuth pentafluoride in hydrofluoric acid solvent also reacts with nickel fluoride to form the nickel salt of this anion, which can be incorporated into a complex with acetonitrile.