Hexaiodobenzene

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Hexaiodobenzene
Hexaiodobenzene.svg
Names
Preferred IUPAC name
Hexaiodobenzene
Other names
Periodobenzene
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.009.246 OOjs UI icon edit-ltr-progressive.svg
PubChem CID
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
Appearanceorange 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°
Related compounds
Related compounds
Hexafluorobenzene
Hexachlorobenzene
Hexabromobenzene
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Hexaiodobenzene is an aryl iodide and a six-substituted iodobenzene 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]

Contents

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]

Related Research Articles

<span class="mw-page-title-main">Iodine</span> Chemical element, symbol I and atomic number 53

Iodine is a chemical element; it has symbol I and atomic number 53. The heaviest of the stable halogens, it exists at standard conditions as a semi-lustrous, non-metallic solid that melts to form a deep violet liquid at 114 °C (237 °F), and boils to a violet gas at 184 °C (363 °F). The element was discovered by the French chemist Bernard Courtois in 1811 and was named two years later by Joseph Louis Gay-Lussac, after the Ancient Greek Ιώδης, meaning 'violet'.

<span class="mw-page-title-main">Lead(II) iodide</span> Chemical compound

Lead(II) iodide is a chemical compound with the formula PbI
2
. At room temperature, it is a bright yellow odorless crystalline solid, that becomes orange and red when heated. It was formerly called plumbous iodide.

<span class="mw-page-title-main">Hydrogen iodide</span> Chemical compound

Hydrogen iodide (HI) is a diatomic molecule and hydrogen halide. Aqueous solutions of HI are known as hydroiodic acid or hydriodic acid, a strong acid. Hydrogen iodide and hydroiodic acid are, however, different in that the former is a gas under standard conditions, whereas the other is an aqueous solution of the gas. They are interconvertible. HI is used in organic and inorganic synthesis as one of the primary sources of iodine and as a reducing agent.

<span class="mw-page-title-main">Sodium iodide</span> Chemical compound

Sodium iodide (chemical formula NaI) is an ionic compound formed from the chemical reaction of sodium metal and iodine. Under standard conditions, it is a white, water-soluble solid comprising a 1:1 mix of sodium cations (Na+) and iodide anions (I) in a crystal lattice. It is used mainly as a nutritional supplement and in organic chemistry. It is produced industrially as the salt formed when acidic iodides react with sodium hydroxide. It is a chaotropic salt.

<span class="mw-page-title-main">Periodate</span> Negatively-charged molecule made of oxygen and iodine

Periodate is an anion composed of iodine and oxygen. It is one of a number of oxyanions of iodine and is the highest in the series, with iodine existing in oxidation state +7. Unlike other perhalogenates, such as perchlorate, it can exist in two forms: metaperiodateIO
4
and orthoperiodateIO5−
6
. In this regard it is comparable to the tellurate ion from the adjacent group. It can combine with a number of counter ions to form periodates, which may also be regarded as the salts of periodic acid.

The tropylium ion or cycloheptatrienyl cation is an aromatic species with a formula of [C7H7]+. Its name derives from the molecule tropine from which cycloheptatriene (tropylidene) was first synthesized in 1881. Salts of the tropylium cation can be stable, even with nucleophiles of moderate strength e.g., tropylium tetrafluoroborate and tropylium bromide (see below). Its bromide and chloride salts can be made from cycloheptatriene and bromine or phosphorus pentachloride, respectively.

Ruthenium tetroxide is the inorganic compound with the formula RuO4. It is a yellow volatile solid that melts near room temperature. It has the odor of ozone. Samples are typically black due to impurities. The analogous OsO4 is more widely used and better known. It is also the anhydride of hyperruthenic acid (H2RuO5). One of the few solvents in which RuO4 forms stable solutions is CCl4.

<span class="mw-page-title-main">Iodine monochloride</span> Chemical compound

Iodine monochloride is an interhalogen compound with the formula ICl. It is a red-brown chemical compound that melts near room temperature. Because of the difference in the electronegativity of iodine and chlorine, this molecule is highly polar and behaves as a source of I+. Discovered in 1814 by Gay-Lussac, iodine monochloride is the first interhalogen compound discovered.

Iodine compounds are compounds containing the element iodine. Iodine can form compounds using multiple oxidation states. Iodine is quite reactive, but it is much less reactive than the other halogens. For example, while chlorine gas will halogenate carbon monoxide, nitric oxide, and sulfur dioxide, iodine will not do so. Furthermore, iodination of metals tends to result in lower oxidation states than chlorination or bromination; for example, rhenium metal reacts with chlorine to form rhenium hexachloride, but with bromine it forms only rhenium pentabromide and iodine can achieve only rhenium tetraiodide. By the same token, however, since iodine has the lowest ionisation energy among the halogens and is the most easily oxidised of them, it has a more significant cationic chemistry and its higher oxidation states are rather more stable than those of bromine and chlorine, for example in iodine heptafluoride.

<span class="mw-page-title-main">Thiophosphoryl chloride</span> Chemical compound

Thiophosphoryl chloride is an inorganic compound with the chemical formula PSCl3. It is a colorless pungent smelling liquid that fumes in air. It is synthesized from phosphorus chloride and used to thiophosphorylate organic compounds, such as to produce insecticides.

Tin(IV) iodide, also known as stannic iodide, is the chemical compound with the formula SnI4. This tetrahedral molecule crystallizes as a bright orange solid that dissolves readily in nonpolar solvents such as benzene.

Boron triiodide is a chemical compound of boron and iodine with chemical formula BI3. It has a trigonal planar molecular geometry.

<span class="mw-page-title-main">Rubidium iodide</span> Chemical compound

Rubidium iodide is a salt of rubidium and iodine, with the chemical formula RbI. It is a white solid with a melting point of 642 °C.

Unlike its lighter congeners, the halogen iodine forms a number of stable organic compounds, in which iodine exhibits higher formal oxidation states than -1 or coordination number exceeding 1. These are the hypervalent organoiodines, often called iodanes after the IUPAC rule used to name them.

<span class="mw-page-title-main">Germanium(IV) iodide</span> Chemical compound

Germanium(IV) iodide is an inorganic compound with the chemical formula GeI4.

<span class="mw-page-title-main">Tetraethylammonium iodide</span> Chemical compound

Tetraethylammonium iodide is a quaternary ammonium compound with the chemical formula C8H20N+I. It has been used as the source of tetraethylammonium ions in pharmacological and physiological studies, but is also used in organic chemical synthesis.

Tetraiodobenzenes form a group of iodobenzenes with four iodine atoms as substituents (C6H2I4). By their different arrangement, three constitutional isomers are possible.

A sulfite sulfate is a chemical compound that contains both sulfite and sulfate anions [SO3]2− [SO4]2−. These compounds were discovered in the 1980s as calcium and rare earth element salts. Minerals in this class were later discovered. Minerals may have sulfite as an essential component, or have it substituted for another anion as in alloriite. The related ions [O3SOSO2]2− and [(O2SO)2SO2]2− may be produced in a reaction between sulfur dioxide and sulfate and exist in the solid form as tetramethyl ammonium salts. They have a significant partial pressure of sulfur dioxide.

<span class="mw-page-title-main">Phosphonium iodide</span> Chemical compound

Phosphonium iodide is a chemical compound with the formula PH
4
I
. It is an example of a salt containing an unsubstituted phosphonium cation. Phosphonium iodide is commonly used as storage for phosphine and as a reagent for substituting phosphorus into organic molecules.

<span class="mw-page-title-main">Praseodymium(III) iodide</span> Chemical compound

Praseodymium(III) iodide is an inorganic salt, consisting of the rare-earth metal praseodymium and iodine, with the chemical formula PrI3. It forms green crystals. It is soluble in water.

References

  1. 1 2 3 4 Mattern, Daniell Lewis (1983). "Periodination of benzene with periodate/Iodide". The Journal of Organic Chemistry. 48 (24): 4772–4773. doi:10.1021/jo00172a063.
  2. 1 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.