Rhenium heptafluoride is the compound with the formula ReF<sub>7</sub>. It is a yellow low melting solid and is the only thermally stable metal heptafluoride. It has a distorted pentagonal bipyramidal structure similar to IF<sub>7</sub>, which was confirmed by neutron diffraction at 1.5 K. The structure is non-rigid, as evidenced by electron diffraction studies.
Rhenium heptafluoride can be prepared from the elements at 400 ðC:
It also can be produced by the explosion of rhenium metal under sulfur hexafluoride.
It hydrolyzes under a base to form perrhenic acid and hydrogen fluoride:
With fluoride donors such as CsF, the anion is formed, which has a square antiprismatic structure. With antimony pentafluoride, SbF<sub>5</sub>, a fluoride acceptor, the cation is formed.