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 [IOF<sub>4</sub>]<sup>âÂÂ</sup>, [IO<sub>2</sub>F<sub>2</sub>]<sup>âÂÂ</sup>, [IO<sub>3</sub>F]<sup>2âÂÂ</sup>, and [I<sub>2</sub>O<sub>5</sub>F<sub>2</sub>]<sup>2âÂÂ</sup>.
They are distinct from the iodate fluorides which are mixed anion compounds that do not have fluorine-iodine bonds.
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 àlonger than the I-O bond. The fluorine atoms repel each other in [IO<sub>2</sub>F<sub>2</sub>]<sup>âÂÂ</sup> and are almost opposite each other. The â OIF angle is close to 90ð and the oxygen atoms â OFO are at about 102ð, so they resemble an octahedral arrangement, with two adjacent positions deleted.