Diiodine pentoxide

Iodine pentoxide

Names
IUPAC name Diiodine pentoxide
Other names Iodine(V) oxide Iodic anhydride
Identifiers
CAS Number	12029-98-0 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:29914 Y
ChemSpider	140179 Y
ECHA InfoCard	100.031.569
PubChem CID	159402
InChI InChI=1S/I2O5/c3-1(4)7-2(5)6 Y Key: BIZCJSDBWZTASZ-UHFFFAOYSA-N Y InChI=1/I2O5/c3-1(4)7-2(5)6 Key: BIZCJSDBWZTASZ-UHFFFAOYAR
SMILES O=I(=O)OI(=O)=O
Properties
Chemical formula	I 2O 5
Molar mass	333.81 g/mol
Appearance	white crystalline solid hygroscopic
Density	4.980 g/cm3
Melting point	300 °C (572 °F; 573 K) (decomposes)
Solubility	soluble in water and nitric acid; insoluble in ethanol, ether and CS2
Magnetic susceptibility (χ)	−79.4·10−6 cm3/mol
Hazards
Main hazards	oxidizer
NFPA 704	0 3 0 OX
Related compounds
Other anions	iodine pentafluoride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YN ?)
Infobox references

Iodine pentoxide is the chemical compound with the formula I₂O₅. This iodine oxide is the anhydride of iodic acid, and the only stable oxide of iodine. It is produced by dehydrating iodic acid at 200 °C in a stream of dry air:

I₂O₅ is bent with an I-O-I angle of 139.2°, but the molecule has no mirror plane so its symmetry is not C_2v. The terminal I-O distances are around 1.80 Å and the bridging I-O distances are around 1.95 Å.

Iodine pentoxide easily oxidises carbon monoxide to carbon dioxide at room temperature:

This reaction can be used to analyse the concentration of CO in a gaseous sample.

I₂O₅ forms iodyl salts, [IO₂⁺], with SO₃ and S₂O₆F₂, but iodosyl salts, [IO⁺], with concentrated sulfuric acid.

Iodine pentoxide decomposes to iodine (vapor) and oxygen when heated to about 350 °C.