Iodine heptafluoride
Chemical compound
From Wikipedia, the free encyclopedia
Iodine heptafluoride is an interhalogen compound with the chemical formula IF7.[2][3] It has an unusual pentagonal bipyramidal structure, with D5h symmetry, 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]
| |||
| |||
| Names | |||
|---|---|---|---|
| Other names
Iodine(VII) fluoride Heptafluoroiodine | |||
| Identifiers | |||
3D model (JSmol) |
|||
| ChemSpider | |||
| ECHA InfoCard | 100.037.241 | ||
PubChem CID |
|||
| UNII | |||
CompTox Dashboard (EPA) |
|||
| |||
| |||
| Properties | |||
| 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 (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).
| |||
Below 4.5 °C, IF7 forms a snow-white powder of colorless crystals, melting at 5–6 °C. However, this melting is difficult to observe, as the liquid form is thermodynamically unstable at 760 mmHg: instead, the compound begins to sublime at 4.77 °C. The dense vapor has a mouldy, acrid odour.[6][7]
Preparation
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.[8][9] 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:[10]
- 2 O2PtF6 + 2 KF + IF5 → 2 KPtF6 + 2 O2 + IF7
Reactions
Iodine heptafluoride decomposes at 200 °C to fluorine gas and iodine pentafluoride.[11]
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.
