Iodine III Species with Three Carbon Ligands

In general, iodine(III) species with three carbon ligands are unstable at room temperature. Only a few examples of isolable compounds of this type were reported in the earlier literature, namely, triphenyl iodine, Ph31 [586,587] and 5-aryl-5//-dibenziodoles [588-591 ]. All triaryliodanes are highly unstable and air sensitive compounds. 

Fluoroaryliodine(III) cyano compounds ArI(CN)2 can form relatively stable adducts with nitrogen bases (phenanthroline, 2,2 -bipyridine and quinoline) the adduct of 4-FC6F4l(CN)2 with 1,10-phenanthroline has been characterized by single-crystal X-ray diffraction [62], 

Azidoiodanes 448 and 449 were proposed as reactive intermediates in synthetically useful azidation reactions involving the combination of PhIO, PhI(OAc)2, or PhICl2 with trimethylsilyl azide or NaNs [595-610]. Attempts to isolate these intermediates always resulted in rapid decomposition at -25 to 0 °C with the formation of iodobenzene and dinitrogen however, low-temperature spectroscopy and the subsequent chemical reactions in situ provided some experimental evidence for the existence of these species. A systematic study of structure and reactivity of these unstable azidoiodanes was attempted by Zbiral and coworkers in the early 1970s [595-598]. In particular, the IR spectroscopic measurements at-60 to 0 °C indicated the existence of PhI(Ns)2 and PhI(N3)OAc species in the mixture of PhI(OAc)2 with trimethylsilyl azide [595]. Interestingly, the absorption band of 2040 cm for the azido group in PhI(N3)OAc is very close to the absorption stretch of 2046-2048 cm in the stable, heterocyclic azidoiodanes 122-124 (Section 2.1.8.1.5). 

The unstable and highly reactive azidoiodanes generated in situ from PhIO, PhI(OAc)2, or PhlCla and trimethylsilyl azide or NaNs have found some practical application as efficient reagents for the introduction of the azido function into organic molecules. 

Amidoiodanes 451 bearing one nitrogen ligand at hypervalent iodine center are plausible intermediates in the Hofmann-type degradation of amides with [bis(acyloxy)iodo]arenes or Diydroxy(tosyloxy)iodo]benzene 

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