Rhenium heptafluoride
Names
IUPAC name
rhenium heptafluoride, heptafluoridorhenium
Identifiers
3D model (JSmol)
ChemSpider
UNII
  • InChI=1S/7FH.Re/h7*1H;/q;;;;;;;+7/p-7 ☒N
    Key: HFHBKXWKPQUYIA-UHFFFAOYSA-G ☒N
  • InChI=1/7FH.Re/h7*1H;/q;;;;;;;+7/p-7/rF7Re/c1-8(2,3,4,5,6)7
    Key: HFHBKXWKPQUYIA-KLJGHBABAK
  • F[Re](F)(F)(F)(F)(F)F
Properties
ReF7
Molar mass 319.196 g/mol
Appearance Bright yellow crystalline solid
Density 4.3 g/cm3
Melting point 48.3 °C (118.9 °F; 321.4 K)
Boiling point 73.72 °C (164.70 °F; 346.87 K)
Reacts
Vapor pressure 13.41 kPa[1]
Structure
triclinic, aP16
P1 (No. 2)
Thermochemistry
Enthalpy of fusion (ΔfH⦵fus)
 7.53 kJ/mol[1]
30.77 kJ/mol[1]
Related compounds
Related compounds
 Osmium heptafluoride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Rhenium heptafluoride is the compound with the formula ReF7. It is a yellow low melting solid and is the only thermally stable metal heptafluoride.[2] It has a distorted pentagonal bipyramidal structure similar to IF7, which was confirmed by neutron diffraction at 1.5 K.[3] The structure is non-rigid, as evidenced by electron diffraction studies.[4]

Production, reactions and properties

Rhenium heptafluoride can be prepared from the elements at 400 °C:[5]

2 Re + 7 F2 → 2 ReF7

It also can be produced by the explosion of rhenium metal under sulfur hexafluoride. [6]

It hydrolyzes under a base to form perrhenic acid and hydrogen fluoride:[1]

ReF7 + 4H2O → HReO4 + 7HF

With fluoride donors such as CsF, the ReF−
8 anion is formed, which has a square antiprismatic structure.[7] With antimony pentafluoride, SbF5, a fluoride acceptor, the ReF+
6 cation is formed.[5]

References

  1. ^ a b c d J.G.Malm; H.Selig (1961). "The vapour-pressures and other properties of ReF6 and ReF7". Journal of Inorganic and Nuclear Chemistry. 20 (3): 189–197. doi:10.1016/0022-1902(61)80267-4.
  2. ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
  3. ^ Vogt T.; Fitch A. N.; Cockcroft J. K. (1994). "Crystal and Molecular Structures of Rhenium Heptafluoride". Science. 263 (5151): 1265–7. Bibcode:1994Sci...263.1265V. doi:10.1126/science.263.5151.1265. PMID 17817431. S2CID 20013073.
  4. ^ Jacob, E. Jean; Bartell, L.S.J. (1970). "Electron Diffraction Study of Rhenium Fluorides. II. Structure, Pseudorotation, and Anharmonic Coupling of Modes in ReF7" (PDF). The Journal of Chemical Physics. 53 (6): 2235. Bibcode:1970JChPh..53.2235J. doi:10.1063/1.1674318. hdl:2027.42/70852.
  5. ^ a b A. F. Holleman; Wiberg, Egon; Wiberg, Nils (2001). Inorganic Chemistry. Boston: Academic Press. ISBN 0-12-352651-5.
  6. ^ Richard L. Johnson; Bernard Siegel (1969). "On the synthesis of ReF7 and the existence of ReF2 and ReF3". Journal of Inorganic and Nuclear Chemistry. 31 (8): 2391–2396. doi:10.1016/0022-1902(69)80569-5.
  7. ^ Hwang, I; Seppelt, K. (2000). "The structures of ReF−
    8     and UF2−
    8    ". Journal of Fluorine Chemistry. 102 (1–2): 69–72. doi:10.1016/S0022-1139(99)00248-1.
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