Date: 27 Nov 2002

Reactivities, Properties and Structures

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Abstract

Tri- and pentavalent iodine compounds are called λ3- and λ5-iodanes. Ligand exchange, i.e. displacement of heteroatom ligands of λ3- and λ5-iodanes with external nucleophiles, is a facile low energy process. A very high leaving group ability of λ3-iodanyl groups is among the most important features of λ3-iodanes, which makes it possible to generates highly reactive species such as carbenes, nitrenes, cations, and arynes under mild conditions and to oxidize a wide range of functionalities such as alcohols, amines, sulfides, alkenes, alkynes, and carbonyl compounds. The leaving process is termed reductive elimination, in which the λ3-iodanyl group eliminates with energetically preferable reduction to univalent iodides. The process is also associates with an increase in entropy. Pseudorotation and ligand coupling on iodine(III), and homolytic cleavage of hypervalent iodanes are also discussed. Finally, recent progress in the structural elucidations of λ3-iodanes is shown here.