Rhenium heptafluoride explained

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 1.5 K.^[1] The structure is non-rigid, as evidenced by electron diffraction studies.^[2]

Production, reactions and properties

Rhenium heptafluoride can be prepared from the elements at 400 °C:^[3]

2 Re + 7 F₂ → 2 ReF₇It also can be produced by the explosion of rhenium metal under sulfur hexafluoride. ^[4]

It hydrolyzes under a base to form perrhenic acid and hydrogen fluoride:

ReF₇ + 4H₂O → HReO₄ + 7HFWith fluoride donors such as CsF, the anion is formed, which has a square antiprismatic structure.^[5] With antimony pentafluoride, SbF₅, a fluoride acceptor, the cation is formed.

Notes and References

1. 10.1126/science.263.5151.1265 . Crystal and Molecular Structures of Rhenium Heptafluoride . 1994 . Vogt T. . Fitch A. N. . Cockcroft J. K. . Science . 263 . 1265–7 . 17817431 . 5151. 1994Sci...263.1265V . 20013073 .
2. 10.1063/1.1674318 . Electron Diffraction Study of Rhenium Fluorides. II. Structure, Pseudorotation, and Anharmonic Coupling of Modes in ReF7 . 1970 . Jacob, E. Jean . Bartell, L.S.J. . The Journal of Chemical Physics . 53 . 2235 . 6. 1970JChPh..53.2235J . 2027.42/70852 . free .
3. Book: A. F. Holleman . Wiberg, Egon . Wiberg, Nils . Inorganic Chemistry . Academic Press . Boston . 2001 . 0-12-352651-5 .
4. Richard L. Johnson . Bernard Siegel . On the synthesis of ReF7 and the existence of ReF2 and ReF3 . Journal of Inorganic and Nuclear Chemistry . 1969 . 31 . 8 . 2391–2396 . 10.1016/0022-1902(69)80569-5 . English.
5. 10.1016/S0022-1139(99)00248-1 . The structures of and . 2000 . Hwang, I . Seppelt, K. . Journal of Fluorine Chemistry . 102 . 1–2. 69–72.