Iodine oxide

Molecular compounds

Diiodine monoxide has largely been the subject of theoretical study, but there is some evidence that it may be prepared in a similar manner to dichlorine monoxide, via a reaction between HgO and I2. The compound appears to be highly unstable but can react with alkenes to give halogenated products.

Radical iodine oxide (IO) and iodine dioxide (IO2), collectively referred to as IOx, and also iodine tetroxide (I2O4) all possess significant and interconnected atmospheric chemistry. They are formed, in very small quantities, in the marine boundary layer by the photochemical reaction of ozone with diiodomethane, produced by macroalga such as seaweed, or through the oxidation of molecular iodine, produced by the reaction of gaseous ozone and iodide present at the seasurface. Despite the small quantities produced (typically below ppt) they are thought to be powerful ozone depletion agents.

Diiodine pentoxide (I2O5) is the anhydride of iodic acid and the only stable anhydride of out of all halogen oxoacids. Unlike other halogen oxides, it can be synthesized by thermal dehydration of iodic acid. Iodine pentoxide adopts multiple polymorphs that can be synthesized by varying pressures.

Tetraiodine nonoxide (I4O9) has been prepared by the gas-phase reaction of I2 with O3 but has not been extensively studied.

Diiodine hexaoxide (I2O6), also known as iodine trioxide or diiodine(V,VII) oxide, is a hygroscopic yellow solid. It has been isolated in bulk and has been studied as a mix with aluminium for destroying chemical and biological agents. It can be synthesized in hot concentrated sulfuric acid, starting either with pure H5IO6 or a mix of H5IO6 and HIO3 It adopts a polymeric structure consisting of IV and IVII centers.

Diiodine heptoxide (I2O7) has been reported as a yellow solid that slowly decomposes into oxygen at room temperature with rapid decomposition beginning at 60 °C, converting it into I2O6.

Iodate anions

Iodine oxides also form negatively charged anions, which (associated with complementary cations) are components of acids or salts. These include the iodates and periodates, which can form multinuclear structures such as [I2O9]4-.

The conjugate acids of the iodine oxides are:

The periodates include two main variants: metaperiodate and orthoperiodate .

References

References

1. (2008). "Quantum chemical calculations on a selection of iodine-containing species (IO, OIO, INO₃, (IO)₂, I₂O₃, I₂O₄ and I₂O₅) of importance in the atmosphere". Physical Chemistry Chemical Physics.
2. {{RubberBible86th
3. (31 August 2008). "Halogen monoxides". Russian Chemical Reviews.
5. Kraft, T., & Jansen, M. (1995). Synthesis and crystal structure of diiodine (V/VII) hexaoxide: An intermediate between a molecular and a polymer solid. Journal of the American Chemical Society, 117(25), 6795-6796.
6. Teichtmeister, T. A., Johrendt, D., Bernhart, A. H., Heymann, G., & Huppertz, H. (2024). A Comparative Study of a High‐Pressure Polymorph of I2O5 and its Ambient‐Pressure Modification. Chemistry–A European Journal, 30(68), e202402801.
7. (1998). "Theoretical study of I2O". Heteroatom Chemistry.
8. (1974). "Hypoiodite reaction: kinetic study of the reaction of 1,1-diphenyl-ethylene with mercury(II) oxide iodine". Journal of the Chemical Society, Perkin Transactions 1.
9. (1976). "Reactions of iodine oxide with alkenes". Journal of the Chemical Society, Perkin Transactions 1.
10. (15 May 2001). "Iodine oxide homogeneous nucleation: An explanation for coastal new particle production". Geophysical Research Letters.
11. (13 January 2013). "Atmospheric iodine levels influenced by seasurface emissions of inorganic iodine". Nature Geoscience.
12. (10 December 2014). "Iodine chemistry in the troposphere and its effect on ozone". Atmospheric Chemistry and Physics.
13. (1 July 1999). "OIO and the atmospheric cycle of iodine". Geophysical Research Letters.
14. (December 1985). "Raman spectra of I₄O₉ formed by the reaction of iodine with ozone". Journal of Raman Spectroscopy.
15. Nikitina, N. I., & Nikitina, Z. K. (2005). Synthesis and interconversion of cesium salts with polynuclear orthoperiodate anions.