Rhenium heptafluoride is the compound with the formula ReF
7. 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 1.5 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 F
2 → 2 ReF
7
It also can be produced by the explosion of
rhenium 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 ...
:
:ReF
7 + 4H
2O → HReO
4 + 7HF
With fluoride donors such as CsF, the ReF
8− 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. ...
, SbF
5, a fluoride acceptor, the ReF
6+ cation is formed.
References
{{Fluorides
Rhenium compounds
Fluorides