Hypervalent organoiodine compounds

Thus when iodine is ligated to an organic residue and two Lewis acids, it is in the +3 oxidation state and the corresponding compound is a λ3‑iodane.

In a λ3‑iodane, each X-type ligand donates an additional electron, for 10 in total; the result is a decet structure.

Cleaner preparations[4] begin with solutions of peracetic acid in glacial acetic acid, also due to Willgerodt:[5] C6H5I + CH3C(O)OOH + CH3COOH → C6H5I(OC(O)CH3)2 + H2OThe iodobenzene diacetate product hydrolyzes to the polymeric iodosobenzene (PhIO), which is stable in cool alkaline solution.

[9] IBX acid is unstable and explosive, but acetylation tempers it to the stabler Dess-Martin periodinane.

[14] They are formally composed of a diaryliodonium cation[15] paired with a counteranion, but crystal structures show a long, weak, partially-covalent bond between the iodine and the counterion.

The first such compound was synthesised in 1894, via the silver hydroxide-catalyzed coupling of two aryl iodides (the Meyer–Hartmann reaction):[19][20][21] Alternatively, the iodane may be formed in situ: an aryl iodide is oxidized to an aryliodine(III) compound (such as ArIO), followed by a ligand exchange.

Diaryliodonium salts react with nucleophiles at iodine, replacing one ligand to form the substituted arene ArNu and iodobenzene ArI.

Hypervalent iodine compounds are predominantly used as oxidizing reagents, although they are specialized and expensive.

A hypervalent iodine (III) reagent was used as oxidant, together with ammonium acetate as nitrogen source, to provide 2-Furonitrile, a pharmaceutical intermediate and potential artificial sweetener.

[24] Current research focuses on the use of iodanes in carbon-carbon and carbon-heteroatom bond-forming reactions.

In one study, an intramolecular C-N coupling of an alkoxyhydroxylamine to its anisole group is accomplished with a catalytic amount of aryliodide in trifluoroethanol.