Iodine heptafluoride

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Iodine heptafluoride
Other names	iodine fluoride heptafluoroiodine
Identifiers
CAS number	[16921-96-3]
Properties
Molecular formula	IF7
Molar mass	259.89 g mol−1
Density	2.7 g cm−3 (solid)
Melting point	4.5°C (triple point)
Boiling point	4.8°C (sublimes at 1 atm)
Solubility in other solvents	? g L−1
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox 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 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 1 Preparation 2 Safety considerations 3 References 4 External links

[edit] 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]}

[edit] Safety considerations

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

[edit] 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. 

[edit] External links

• National Pollutant Inventory - Flouride and compounds fact sheet
• web elements listing