Iodine heptafluoride

Iodine heptafluoride is an interhalogen compound with the chemical formula IF₇.^[2][3] It has an unusual pentagonal bipyramidal structure, with D_5h 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]

Iodine heptafluoride

Structure of iodine heptafluoride(IF7)
Iodine heptafluoride Iodine heptafluoride
Names
Other names Iodine(VII) fluoride Heptafluoroiodine
Identifiers
CAS Number	16921-96-3 Y
3D model (JSmol)	Interactive image
ChemSpider	21477354 Y
ECHA InfoCard	100.037.241
PubChem CID	85645
UNII	M080M03ILM Y
CompTox Dashboard (EPA)	DTXSID8066133
InChI InChI=1S/F7I/c1-8(2,3,4,5,6)7 Y Key: XRURPHMPXJDCOO-UHFFFAOYSA-N Y InChI=1/F7I/c1-8(2,3,4,5,6)7 Key: XRURPHMPXJDCOO-UHFFFAOYAO
SMILES FI(F)(F)(F)(F)(F)F
Properties
Chemical 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 (40.1 °F; 277.6 K) (triple point)
Boiling point	4.8 °C (40.6 °F; 277.9 K) (sublimes at 1 atm)
Solubility in water	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). N verify (what is YN ?) Infobox references

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.