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 bipyramid In geometry, the pentagonal bipyramid (or dipyramid) is third of the infinite set of face-transitive bipyramids, and the 13th Johnson solid (). Each bipyramid is the dual of a uniform prism. Although it is face-transitive, it is not a Platoni ...

al structure similar to IF₇, which was confirmed by neutron diffraction at 1.5 K. The structure is non-rigid, as evidenced by electron diffraction studies.

Production, reactions and properties

Rhenium heptafluoride can be prepared from the elements at 400 °C: :2 Re + 7 F₂ → 2 ReF₇ It also can be produced by the explosion of

rhenium Rhenium is a chemical element with the symbol Re and atomic number 75. It is a silvery-gray, heavy, third-row transition metal in group 7 of the periodic table. With an estimated average concentration of 1 part per billion (ppb), rhenium is one ...

metal under

sulfur hexafluoride Sulfur hexafluoride or sulphur hexafluoride (British spelling) is an inorganic compound with the formula SF6. It is a colorless, odorless, non- flammable, and non-toxic gas. has an octahedral geometry, consisting of six fluorine atoms attached ...

. It hydrolyzes under a base to form

perrhenic acid Perrhenic acid is the chemical compound with the formula . It is obtained by evaporating aqueous solutions of . Conventionally, perrhenic acid is considered to have the formula , and a species of this formula forms when rhenium(VII) oxide sublime ...

and

hydrogen fluoride Hydrogen fluoride (fluorane) is an inorganic compound with the chemical formula . This colorless gas or liquid is the principal industrial source of fluorine, often as an aqueous solution called hydrofluoric acid. It is an important feedstock i ...

: :ReF₇ + 4H₂O → HReO₄ + 7HF With fluoride donors such as CsF, the ReF₈⁻ anion is formed, which has a square antiprismatic structure. With

antimony pentafluoride Antimony pentafluoride is the inorganic compound with the formula Sb F5. This colourless, viscous liquid is a valuable Lewis acid and a component of the superacid fluoroantimonic acid, formed when mixing liquid HF with liquid SbF5 in a 2:1 ratio. ...

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

References

{{Fluorides Rhenium compounds Fluorides