Iodine heptafluoride

Iodine heptafluoride, also known as iodine(VII) fluoride or iodine fluoride, is an interhalogen compound with the chemical formula IF7.[2][3] It has an unusual pentagonal bipyramidal structure, as predicted by VSEPR theory.[4] The molecule can undergo a pseudorotational rearrangement called the Bartell mechanism, which is like the Berry mechanism but for a heptacoordinated system.[5] It forms colourless 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 mouldy, acrid odour. The molecule has D5h symmetry.

Iodine heptafluoride
Structure of iodine heptafluoride(IF7)
Iodine heptafluoride
Iodine heptafluoride
Other names
Iodine(VII) fluoride
3D model (JSmol)
ECHA InfoCard 100.037.241 Edit this at Wikidata
  • InChI=1S/F7I/c1-8(2,3,4,5,6)7 checkY
  • InChI=1/F7I/c1-8(2,3,4,5,6)7
  • FI(F)(F)(F)(F)(F)F
Molar mass 259.90 g/mol
Appearance colorless gas
Density 2.6 g/cm3 (6 °C)
2.7 g/cm3 (25 °C)
Melting point 4.5 °C (40.1 °F; 277.6 K) (triple point)
Boiling point 4.8 °C (40.6 °F; 277.9 K) (sublimes at 1 atm)
soluble [1]
Related compounds
Related compounds
iodine pentafluoride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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IF7 is prepared by passing F2 through liquid IF5 at 90 °C, then heating the vapours to 270 °C. Alternatively, this compound can be prepared from fluorine and dried palladium or potassium iodide to minimize the formation of IOF5, an impurity arising by hydrolysis.[6][7] Iodine heptafluoride is also produced as a by-product when dioxygenyl hexafluoroplatinate is used to prepare other platinum(V) compounds such as potassium hexafluoroplatinate(V), using potassium fluoride in iodine pentafluoride solution:[8]

2 O2PtF6 + 2 KF + IF5 → 2 KPtF6 + 2 O2 + IF7


Iodine heptafluoride decomposes at 200 °C to fluorine gas and iodine pentafluoride.[9]

Safety considerationsEdit

IF7 is highly irritating to both the skin and the mucous membranes. It also is a strong oxidizer and can cause fire on contact with organic material.


  1. ^ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0-07-049439-8
  2. ^ Macintyre, J. E. (Ed.). (1992). Dictionary of Inorganic Compounds (Vol. 3). London: Chapman & Hall.
  3. ^ O'Neil, Maryadele J. (Ed.). (2001). The Merck Index (13th ed.). Whitehouse Station, NJ: Merck.
  4. ^ K. O. Christe; E. C. Curtis; D. A. Dixon (1993). "On the problem of heptacoordination: vibrational spectra, structure, and fluxionality of iodine heptafluoride". Journal of the American Chemical Society. 115 (4): 1520–1526. doi:10.1021/ja00057a044.
  5. ^ W. J. Adams; H. Bradford Thompson; L. S. Bartell (1970). "Structure, Pseudorotation, and Vibrational Mode Coupling in IF7: An Electron Diffraction Study" (PDF). Journal of Chemical Physics. 53 (10): 4040–4046. Bibcode:1970JChPh..53.4040A. doi:10.1063/1.1673876. hdl:2027.42/71219.
  6. ^ Schumb, W. C.; Lynch, M. A. (1950). "Iodine Heptafluoride". Industrial & Engineering Chemistry. 42 (7): 1383–1386. doi:10.1021/ie50487a035.
  7. ^ Ruff, O.; Keim, R. (1930). ""Das Jod-7-fluorid" (The iodine-7-fluoride)". Zeitschrift für Anorganische und Allgemeine Chemie (in German). 193 (1/2): 176–186. doi:10.1002/zaac.19301930117.
  8. ^ Beveridge, A. D.; Clark, H. C. (1967). "Pentahalides of the Transition Metals". In Gutmann, Viktor (ed.). Halogen Chemistry. Vol. 3. Academic Press. pp. 179–226. ISBN 9780323148474.
  9. ^ Кнунянц, И. Л. (1990). Химическая энциклопедия : в пяти томах (in Russian). Советская Энциклопедия. p. 496. ISBN 5-85270-008-8. OCLC 19556260.

External linksEdit