Tetraiodine nonoxide

Tetraiodine nonoxide is an iodine oxide with the chemical formula I₄O₉.

Preparation

Tetraiodine nonoxide can be produced by reacting ozone and iodine in carbon tetrachloride at −78 °C:

2 I₂ + 9 O₃ → I₄O₉ + 9 O₂

It can also be produced by heating iodic acid and phosphoric acid together:

8 HIO₃ → 2 I₄O₉ + 4 H₂O + O₂

Properties

Tetraiodine nonoxide is a light yellow solid that can easily hydrolyze. It decomposes above 75 °C:

4 I₄O₉ → 6 I₂O₅ + 2 I₂ + 3 O₂

Like diiodine tetroxide, tetraiodine nonoxide contains both I(III) and I(V), and disproportionate to iodate and iodide under alkaline conditions:

3 I₄O₉ + 12 HO⁻ → I⁻ + 11 IO−3 + 6 H₂O

It reacts with water to form iodic acid and iodine:

4 I₄O₉ + 9 H₂O → 18 HIO₃ + I₂

References