Rhenium heptafluoride is the compound with the formula ReF₇. It is a yellow low melting solid, and is the only thermally stable metal heptafluoride. It has a distorted pentagonal bipyramidal structure similar to IF₇, which was confirmed by neutron diffraction at 1.5K. The structure is non-rigid as evidenced by electron diffraction studies.

It can be prepared from the elements at 400°C. With fluoride donors such as CsF, the ReF₈⁻ anion is formed, which has a square antiprism

Square antiprism

In geometry, the square antiprism is the second in an infinite set of antiprisms formed by an even-numbered sequence of triangle sides closed by two polygon caps...

atic structure. With antimony pentafluoride

Antimony pentafluoride

Antimony pentafluoride is the inorganic compound with the formula SbF5. This colourless, viscous liquid is a valuable Lewis acid and a component of the superacid fluoroantimonic acid, the strongest known acid...

, SbF₅, a fluoride acceptor, the ReF₆⁺ cation is formed.