Iodine heptafluoride

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Iodine heptafluoride
Structure of the iodine heptafluoride molecule Iodine heptafluoride Iodine heptafluoride
Systematic name iodine(VII) fluoride
iodine heptafluoride
Other names iodine fluoride
Molecular formula IF7
Molar mass 259.89 g mol−1
Density 2.7 g cm−3 (solid)
Solubility (water) ? g L−1
Melting point 6.5°C (triple point)
Boiling point 4.8°C (sublimes at 1 atm)
CAS number [16921-96-3]
Disclaimer and references

Iodine heptafluoride, also known as iodine(VII) fluoride or even iodine fluoride, is the compound IF7 [1] [2]. It has an unusual pentagonal bipyramidal structure, as predicted by VSEPR theory.[3] The molecule can undergo a pseudorotational rearangment like the Berry mechanism but for a hepta coordinated system. [4] It forms colorless crystals, which melt at 4.5°C: the liquid range is extremely narrow, with the boiling point at 4.77°C. The dense vapor has a moldy, acrid odor.


IF7 is prepared by passing F2 through liquid IF5 at 90 °C, then heating the vapors to 270 °C. Alternately, this compound can be prepared from fluorine and dried PdI2 or KI to minimize the formation of IOF5, an impurity arising by hydrolysis.[5] [6]

Safety considerations

IF7 is highly irritating to both the skin and the mucous membranes.


  1. Macintyre, J. E. (Ed.). (1992). Dictionary of Inorganic Compounds (Vol. 3). London: Chapman & Hall.
  2. O'Neil, Maryadele J. (Ed.). (2001). The Merck Index (13th ed.). Whitehouse Station, NJ: Merck.
  3. K. O. Christe, E. C. Curtis, D. A. Dixon (1993). "On the problem of heptacoordination: vibrational spectra, structure, and fluxionality of iodine heptafluoride". Industrial & Engineering Chemistry. 115 (4): 1520–1526. doi:10.1021/ja00057a044.
  4. W. J. Adams, H. Bradford Thompson, L. S. Bartell (1970). "Structure, Pseudorotation, and Vibrational Mode Coupling in IF7: An Electron Diffraction Study". Journal of Chemical Physics. 53 (10): 4040–4046. doi:10.1063/1.1673876.
  5. W. C. Schumb, M. A. Lynch, Jr. (1950). "Iodine Heptafluoride". Industrial & Engineering Chemistry. 42 (7): 1383–1386. doi:10.1021/ie50487a035.
  6. Ruff O., Keim R. (1930). ""Das Jod-7-fluorid" (The iodine-7-fluoride)". Zeitschrift für Anorganische un Allgemeine Chemie. 193 (1/2): 176–186. doi:10.1002/zaac.19301930117.

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