Iodosobenzene

Iodosobenzene

Names
IUPAC name Iodosylbenzene
Other names Iodosobenzene
Identifiers
CAS Number	536-80-1
ChemSpider	83171
Jmol 3D model	Interactive image
PubChem	92125
InChI InChI=1S/C6H5IO/c8-7-6-4-2-1-3-5-6/h1-5H Key: JYJVVHFRSFVEJM-UHFFFAOYSA-N InChI=1/C6H5IO/c8-7-6-4-2-1-3-5-6/h1-5H Key: JYJVVHFRSFVEJM-UHFFFAOYAR
SMILES c1ccc(cc1)I=O
Properties
Chemical formula	C6H5IO
Molar mass	220.01 g mol^−1
Appearance	colourless solid
Density	1.229 g cm^−3
Melting point	210 ˚C
Solubility in water	poor
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Iodosobenzene or iodosylbenzene is an organoiodine compound with the empirical formula C₆H₅IO. This colourless solid compound is used as an oxo transfer reagent in research laboratories examining organic and coordination chemistry. It is related to the more popular reagent periodinane.

Preparation and structure

Polymeric structure of solid PhIO

Iodosobenzene was first described by Conrad Willgerodt from iodobenzene.^[1] It is prepared by first oxidizing iodobenzene to the diacetate followed by hydrolysis:^[2]

C₆H₅I + CH₃CO₃H + CH₃CO₂H → C₆H₅I(O₂CCH₃)₂ + H₂O

C₆H₅I(O₂CCH₃)₂ + H₂O → C₆H₅IO + 2 CH₃CO₂H

The structure of iodosobenzene remains unverified crystallographically. Its low solubility in most solvents and vibrational spectroscopy indicate that it is not molecular, but is polymeric, consisting of I-O-I-O chains.^[3] The related diacetate, C₆H₅I(O₂CCH₃)₂, illustrates the ability of iodine(III) to adopt a T-shaped geometry without multiple bonds.^[4] Theoretical studies show that the bonding between the iodine and oxygen atoms in iodosobenzene represents a single dative I-O sigma bond, confirming the absence of the double I=O bond.^[5]

Applications

Iodosobenzene has no commercial uses, but in the laboratory it is employed as an "oxo-transfer reagent." It epoxidizes certain alkenes and converts some metal complexes into the corresponding oxo derivatives. Although it is an oxidant, it is also mildly nucleophilic. The active agent in these oxo-transfer reactions is assumed to be monomeric PhI=O, but this aspect remains unverified.

Safety

This compound is explosive and should not be heated under vacuum.

References

1. C. Willgerodt (1892). "Zur Kenntniss aromatischer Jodidchloride, des Jodoso- und Jodobenzols". Ber. 25 (2): 3494–3502. doi:10.1002/cber.189202502221.
2. H. Saltzman and J. G. Sharefkin (1973). "Iodosylbenzene". Org. Synth.; Coll. Vol. 5, p. 658
3. Hans Siebert, Monika Handrich (1976). "Schwingungsspektren und Struktur von Jodosyl- und Jodyl-Verbindungen". Z. anorg. allg. Chem. 426 (2): 173–183. doi:10.1002/zaac.19764260206.
4. C. J. Carmalt, J. G. Crossley, J. G. Knight, P. Lightfoot, A. Martín, M. P. Muldowney, N. C. Norman, A. G. Orpen (1994). "An examination of the structures of iodosylbenzene (PhIO) and the related imido compound, PhINSO₂-4-Me-C₆H₄, by X-ray powder diffraction and EXAFS (extended X-ray absorption fine structure) spectroscopy". J. Chem. Soc., Chem. Commun. (20): 2367. doi:10.1039/C39940002367.
5. Ivanov, A.; Popov, A.; Boldyrev, A.; Zhdankin, V. (2014). "The I=X (X = O,N,C) Double Bond in Hypervalent Iodine Compounds: Is it Real?". Angew. Chem. Int. Ed. doi:10.1002/anie.201405142.