Iodine heptafluoride

Iodine heptafluoride
Other names

iodine fluoride
heptafluoroiodine
Identifiers
CAS number 16921-96-3
ChemSpider 21477354 Y
Jmol-3D images Image 1
Properties
Molecular formula IF7
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 (triple point)
Boiling point

4.8°C (sublimes at 1 atm)
Solubility in water soluble [1]
Related compounds
Related compounds iodine pentafluoride
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Iodine heptafluoride, also known as iodine(VII) fluoride or even iodine fluoride, is an interhalogen compound with 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 hepta coordinated 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.

Contents

Preparation

IF7 is prepared by passing F2 through liquid IF5 at 90 °C, then heating the vapours to 270 °C. Alternately, 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]

Safety considerations

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.

References

  1. ^ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0070494398
  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". Industrial & Engineering Chemistry 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". Journal of Chemical Physics 53 (10): 4040–4046. doi:10.1063/1.1673876. 
  6. ^ W. C. Schumb, M. A. Lynch, Jr. (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 193 (1/2): 176–186. doi:10.1002/zaac.19301930117. 

External links