Hexaiodobenzene

Hexaiodobenzene is a chemical compound with the formula C6I6. Structurally, it is a derivative of benzene, in which all hydrogen atoms are replaced by iodine atoms. It forms orange crystals[1] that are poorly soluble in all solvents. It adopts the expected structure with a central C6 ring.[3]

Hexaiodobenzene
Names
Preferred IUPAC name
Hexaiodobenzene
Other names
Periodobenzene
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.009.246
UNII
  • InChI=1S/C6I6/c7-1-2(8)4(10)6(12)5(11)3(1)9
    Key: QNMKKFHJKJJOMZ-UHFFFAOYSA-N
  • InChI=1/C6I6/c7-1-2(8)4(10)6(12)5(11)3(1)9
    Key: QNMKKFHJKJJOMZ-UHFFFAOYAO
  • C1(=C(C(=C(C(=C1I)I)I)I)I)I
Properties
C6I6
Molar mass 833.493 g·mol−1
Appearance orange crystals[1]
Density 4.60 g/cm3
Melting point 430 °C (806 °F; 703 K)[1]
insoluble
Structure[2]
monoclinic
P21/c, No. 14
a = 8.87 Å, b = 4.29 Å, c = 16.28 Å
α = 90°, β = 93°, γ = 90°
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Preparation

The compound was first prepared by iodination of benzoic acid in the presence of hot fuming sulfuric acid.[4] Another method of synthesis is the reaction between benzene with periodic acid and potassium iodide in sulfuric acid at 100 °C. This method instead produces 1,2,4,5-tetraiodobenzene if done at room temperature.[5]

Properties

Physical properties

Hexaiodobenzene forms orange needles that are practically insoluble in water, but sparingly soluble in N-methyl-2-pyrrolidone and dimethyl sulfoxide. It melts at 430 °C, but also already begins to show some decomposition at 370 °C, forming I2.[1]

Crystallographic properties

The crystals are monoclinic and pseudohexagonal, with centrosymmetric C6I6 units. The carbon atoms lie in a plane with C–C distances about 141 pm, while the nearby iodine atoms show very small displacements (about 4 pm) above and below the ring. The shortest intermolecular distance, 376 pm, is notably short compared to twice the Van der Waals radius, which is 430 pm.[2] The structure is retained at high pressures up to 9.7 GPa.[6]

References
  1. Daniell Lewis Mattern: Periodination of Benzene with Periodate/Iodide, J. Org. Chem., 1983, 48 (24), pp. 4772–4773 (doi:10.1021/jo00172a063; PDF).
  2. Steer, Rosemary J.; Watkins, S. F.; Woodward, P. (1970). "Crystal and molecular structure of hexaiodobenzene". Journal of the Chemical Society C: Organic (2): 403. doi:10.1039/j39700000403. ISSN 0022-4952.
  3. Ghosh, Sandip; Reddy, C. Malla; Desiraju, Gautam R. "Hexaiodobenzene: a redetermination at 100 K", Acta Crystallographica, Section E: Structure Reports Online, 2007, 63(2), o910–o911 (doi:10.1107/S1600536807002279).
  4. Erwin Rupp "Ueber die perhalogenirten Phtalsäuren und das Hexajodbenzol", Chem. Ber., 1896, Volume 29, pp. 1625–1634 (doi:10.1002/cber.18960290293).
  5. Mattern, Daniell Lewis (1983). "Periodination of benzene with periodate/iodide". The Journal of Organic Chemistry. 48 (24): 4772–4773. doi:10.1021/jo00172a063. ISSN 0022-3263.
  6. Nakayama, Atsuko; Fujihisa, Hiroshi; Aoki, Katsutoshi; Carlón, Raquel Pérez (2000-10-01). "Structural study of hexaiodobenzene up to 9.7 GPa". Physical Review B. 62 (13): 8759–8765. doi:10.1103/PhysRevB.62.8759. ISSN 0163-1829.
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.