Iodine pentoxide

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 C2v. The terminal I-O distances are around 1.80 Å and the bridging I-O distances are around 1.95 Å.

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.