The iodite ion, or iodine dioxide anion, is the halite with the chemical formula IO− 2. Within the ion, the iodine exists in the oxidation state of +3.

Iodite anion

Iodites (including iodous acid) are highly unstable and have been observed but never isolated.[citation needed] They will rapidly disproportionate to molecular iodine and iodates. However, they have been detected as intermediates in the conversion between iodide and iodate.

Other oxyanions

Iodine can assume oxidation states of −1, +1, +3, +5, or +7. A number of neutral iodine oxides are also known.

Iodine oxidation state−1+1+3+5+7
Nameiodidehypoioditeioditeiodateperiodate
FormulaI−IO−IO− 2IO− 3IO− 4 or IO5− 6