Iodine is element 53, in the 5th period, Group 17, halogens of the periodic table. Iodine is a large-sized halogen element, easily polarizable, and low in electronegativity. It forms hypervalent organoiodanes beyond the octet theory by readily extending its valence. For example, hypervalent organoiodane with three ligands is a 10-I-3 type compound as shown in the figure. The central iodine atom forms a plane with two lone pairs and one σ-bond, and furthermore, this iodine atom coordinates two ligands with larger electronegativity in an apical position orthogonal to the plane resulting in the formation of a linear three center-four electron bond. The I-L bond in the apical position is weaker and longer than the covalent bond. For example, the I-O bond lengths in PhI(OAc)₂ are longer than the sum of their covalent bond radii (1.99 Å) and these bond lengths have a range of 2.15~2.16 Å.

The stability and reactivity of hypervalent organoiodanes exhibit a greater dependence on the character of hypervalent bonds in the apical position. The hypervalent bonds in the apical position are easily cleaved, and the cleavage causes trivalent iodines with 10 electrons to be reduced to monovalent iodines of a more stable octet structure. For this reason it exhibits good elimination
and oxidation rate and finds application in organic syntheses.^1~3) (Diacetoxyiodo)benzene, the most typical trivalent iodine compounds, which is attempted to support the polymers. For example, Togo and co-workers have demonstrated several oxidative functional group conversion reactions using poly[4-(diacetoxyiodo)styrene].⁴⁾ After reaction, this polymer-supported reagent can be recovered by filtration and reused after re-oxidation with peracetic acid. Therefore, it is expected to be used as environmentally-friendly chemical conversion reagent in the near future.

B2539	B1175	B1616
B2359	B2121	D2045
D2372	D2503	D2356
D2248	D2238	D2373
D2357	D2243	D2253
E0467	P1298	P1015
I0330	I0479	I0073
I0591	P1080	P1659
P1081	P1082	P1620
P1415	T2624	P1239

Many hypervalent organoiodanes may decompose violently when exposed to heat, shock, and friction, etc.. Sufficient safety measures, such as usage of safety shield, wearing of protective equipment, and extreme caution should be taken, when using this compound, from the opening up to the disposal of the reagents.