Iodine heptafluoride

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.

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Preparation

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.

References

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.