Fluoroiodate

A fluorooxoiodate or fluoroiodate is a chemical compound or ion derived from iodate, by substituting some of the oxygen by fluorine. They have iodine in the +5 oxidation state. The iodine atoms have a stereochemically active lone-pair of electrons. Many are non-centrosymmetric, and are second harmonic generators (SHG) of intense light shining through them. They are under investigation as materials for non-linear optics, such as for generating ultraviolet light from visible or infrared lasers.

Different ions include [IOF4]−, [IO2F2]−, [IO3F]2−, and [I2O5F2]2−.

They are distinct from the fluoride iodates which are mixed anion compounds that do not have fluorine-iodine bonds.

Properties
Fluoroiodates are transparent in visible, longer wave ultraviolet and some of the infrared electromagnetic bands.

Compared to iodate, the I-O bonds are shorter, and I-F bonds are longer in fluoroiodates. The I-F bond is about 0.2 Å longer than the I-O bond. The fluorine atoms repel each other in [IO2F2]− and are almost opposite each other. The ∠OIF angle is close to 90° and the oxygen atoms ∠OFO are at about 102°, so they resemble an octahedral arrangement, with two adjacent positions deleted.