Polyiodide

The polyiodides can be made by addition of stoichiometric amounts of I2 to solutions containing I− and I−3, with the presence of large countercations to stabilize them.

For example, KI3·H2O can be crystallized from a saturated solution of KI when a stoichiometric amount of I2 is added and cooled.

[15][16] Polyiodide has been used to improve the scalability in the synthesis of halide perovskite photovoltaic materials.

[17] Solid state compounds containing linear-chain polyiodide ions exhibit enhanced conductivity[18][19] than their simple iodide counterparts.

The conductivity can be drastically modified by external pressure, which changes the interatomic distances between iodine moieties and the charge distribution.

The 14-membered ring array of iodine atoms in [([16]aneS 4 )PdIPd([16]aneS 4 )][I 11 ]
The primitive cubic lattice of iodide ions bridge by I 2 molecules, present in [Cp* 2 Fe] 4 [I 26 ]
Structures of some polyiodide ions.