Iodine heptafluoride

Iodine heptafluoride
Names
	Other names Iodine(VII) fluoride; Heptafluoroiodine
Identifiers
CAS Number	16921-96-3 ;
3D model (JSmol)	Interactive image;
ChemSpider	21477354 ;
ECHA InfoCard	100.037.241
PubChem CID	85645;
UNII	M080M03ILM ;
CompTox Dashboard (EPA)	DTXSID8066133 ;
	InChI InChI=1S/F7I/c1-8(2,3,4,5,6)7 Key: XRURPHMPXJDCOO-UHFFFAOYSA-N ; 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
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). verify (what is ?) Infobox references

Iodine heptafluoride is an interhalogen compound with the chemical formula I F₇. It has an unusual pentagonal bipyramidal structure, with D_5h symmetry, as predicted by VSEPR theory. The molecule can undergo a pseudorotational rearrangement called the Bartell mechanism, which is like the Berry mechanism but for a heptacoordinated system.

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.