Iodine pentoxide

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IUPACName = diiodine pentoxide
OtherNames = iodine(V) oxide; iodic anhydride
Section1 = Chembox Identifiers
CASNo = 12029-98-0
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Section2 = Chembox Properties
Formula = I₂O₅
MolarMass = 333.81 g/mol
Appearance = white crystalline solidGreenwood&Earnshaw pp. 851-852]
Density = 4.980 g cm⁻³
MeltingPt = ? °C
BoilingPt = ? °C
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Section3 = Chembox Hazards
MainHazards = oxidizer
FlashPt =
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Iodine pentoxide is the chemical compound with the formula I₂O₅. This iodine oxide is the anhydride of iodic acid. It is produced by dehydrating iodic acid at 200 °C in a stream of dry air:

:2HIO₃ → I₂O₅ + H₂O

Structure

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 [cite journal | author = K. Selte and A. Kjekshus | year = 1970 | title = Iodine oxides: part III, The crystal structure of I₂O₅ | journal = Acta Chemica Scandinavica | volume = 24 | pages = 1912–1914 ] .

Reactions

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

:5CO + I₂O₅ → I₂ + 5CO₂

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.

References