Periodate

The periodate ion is IO₄⁻ or IO₆⁵⁻. It comes from periodic acid.

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A periodate is a compound that contains this group. Note that the pronunciation is per-iodate, not period-ate.

Examples

• sodium periodate, NaIO₄
• potassium periodate, KIO₄

See category for a bigger list.

Discussion

Periodates include two forms. The metaperiodate ion is IO₄⁻; the orthoperiodate ion is IO₆⁵⁻.

Periodate compounds include metaperiodates and orthoperiodates. Usually both are called periodates.

In neutral or weak acid conditions, IO₄⁻ is most common, in equilibrium with a smaller amount of H₄IO₆⁻. In basic conditions, H₃IO₆²⁻ is formed, plus some other ions.

Like its neighbor, tellurium, and unlike lighter halogens, iodine tends to be hexacoordinate, and the units H_nIO₆^(5−n)- are quite common; but in the case of iodine, tetracoordinate units, such as IO₄⁻, are also quite common.

Uses

Periodates can cleave carbon-carbon bonds when both carbon atoms bear an oxygen atom, either in the form of a hydroxyl or a carbonyl group. This property is often utilized in molecular biochemistry for the purposes of modifying saccharide rings, as many five- and six-membered sugars often have vicinal diols.