Selenium tetrachloride

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Selenium tetrachloride
SeCl4-from-alpha-xtal-1981-CM-3D-ellipsoids.png
TeCl4structure.jpg
Names
IUPAC name
Selenium tetrachloride
Other names
Selenium(IV) chloride, tetrachloro-λ4-selane
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.030.036 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 233-053-5
PubChem CID
RTECS number
  • VS7875000
UNII
  • InChI=1S/Cl4Se/c1-5(2,3)4 Yes check.svgY
    Key: LNBXMNQCXXEHFT-UHFFFAOYSA-N Yes check.svgY
  • InChI=1/Cl4Se/c1-5(2,3)4
    Key: LNBXMNQCXXEHFT-UHFFFAOYAD
  • Cl[Se](Cl)(Cl)Cl
Properties
SeCl4
Molar mass 220.771 g/mol
Appearancewhite to yellow crystals
Density 2.6 g/cm3, solid
Melting point sublimes at 191.4 °C [1]
decomposes in water
Structure
Monoclinic, mS80
C12/c1, No. 15
Seesaw (gas phase)[ citation needed ]
Hazards [2]
GHS labelling:
GHS-pictogram-skull.svg GHS-pictogram-silhouette.svg GHS-pictogram-pollu.svg
Danger
H301, H331, H373, H410
P260, P261, P264, P270, P271, P273, P301+P310, P304+P340, P311, P314, P321, P330, P391, P403+P233, P405, P501
NFPA 704 (fire diamond)
3
0
2
W
Flash point non-flammable
Related compounds
Other anions
Selenium tetrafluoride
Selenium tetrabromide
Selenium dioxide
Other cations
Dichlorine monoxide
Sulfur tetrachloride
Tellurium tetrachloride
Related compounds
Selenium dichloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Selenium tetrachloride is the inorganic compound composed with the formula SeCl4. This compound exists as yellow to white volatile solid. It is one of two commonly available selenium chlorides, the other example being selenium monochloride, Se2Cl2. SeCl4 is used in the synthesis of other selenium compounds.

Contents

Synthesis and structure

The compound is prepared by treating selenium with chlorine. [3] When the reacting selenium is heated, the product sublimes from the reaction flask. The volatility of selenium tetrachloride can be exploited to purification of selenium.

Solid SeCl4 is actually a tetrameric cubane-type cluster, for which the Se atom of an SeCl6 octahedron sits on four corners of the cube and the bridging Cl atoms sit on the other four corners. The bridging Se-Cl distances are longer than the terminal Se-Cl distances, but all Cl-Se-Cl angles are approximately 90°. [4]

SeCl4 has often been used as an example for teaching VSEPR rules of hypervalent molecules. As such, one would predict four bonds but five electron groups giving rise to a seesaw geometry. This clearly is not the case in the crystal structure. Others have suggested that the crystal structure can be represented as SeCl3+ and Cl. This formulation would predict a pyramidal geometry for the SeCl3+ cation with a Cl-Se-Cl bond angle of approximately 109°. However, this molecule is an excellent example of a situation where maximal bonding cannot be achieved with the simplest molecular formula. The formation of the tetramer (SeCl4)4, [5] with delocalized sigma bonding of the bridging chloride is clearly preferred over a "hypervalent" small molecule. Gaseous SeCl4 contains SeCl2 and chlorine, which recombine upon condensation.

Reactions

Selenium tetrachloride can be reduced in situ to the dichloride using triphenylstibine:

SeCl4 + SbPh3 → SeCl2 + Cl2SbPh3

Selenium tetrachloride reacts with water to give selenous and hydrochloric acids: [6] [ page needed ]

SeCl4 + 3 H2O → H2SeO3 + 4 HCl

Upon treatment with selenium dioxide, it gives selenium oxychloride: [6] [ page needed ]

SeCl4 + SeO2 → 2SeOCl2

Related Research Articles

<span class="mw-page-title-main">Octet rule</span> Chemical rule of thumb

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Silicon tetrachloride or tetrachlorosilane is the inorganic compound with the formula SiCl4. It is a colourless volatile liquid that fumes in air. It is used to produce high purity silicon and silica for commercial applications.

<span class="mw-page-title-main">Titanium tetrachloride</span> Inorganic chemical compound

Titanium tetrachloride is the inorganic compound with the formula TiCl4. It is an important intermediate in the production of titanium metal and the pigment titanium dioxide. TiCl4 is a volatile liquid. Upon contact with humid air, it forms thick clouds of titanium dioxide and hydrochloric acid, a reaction that was formerly exploited for use in smoke machines. It is sometimes referred to as "tickle" or "tickle 4" due to the phonetic resemblance of its molecular formula to the word.

In chemistry, an interhalogen compound is a molecule which contains two or more different halogen atoms and no atoms of elements from any other group.

Tin(IV) chloride, also known as tin tetrachloride or stannic chloride, is an inorganic compound with the formula SnCl4. It is a colorless hygroscopic liquid, which fumes on contact with air. It is used as a precursor to other tin compounds. It was first discovered by Andreas Libavius (1550–1616) and was known as spiritus fumans libavii.

<span class="mw-page-title-main">Phosphorus pentachloride</span> Chemical compound

Phosphorus pentachloride is the chemical compound with the formula PCl5. It is one of the most important phosphorus chlorides, others being PCl3 and POCl3. PCl5 finds use as a chlorinating reagent. It is a colourless, water-sensitive and moisture-sensitive solid, although commercial samples can be yellowish and contaminated with hydrogen chloride.

Selenic acid is the inorganic compound with the formula H2SeO4. It is an oxoacid of selenium, and its structure is more accurately described as O2Se(OH)2. It is a colorless compound. Although it has few uses, its derivative sodium selenate is used in the production of glass and animal feeds.

<span class="mw-page-title-main">Tellurium tetrachloride</span> Chemical compound

Tellurium tetrachloride is the inorganic compound with the empirical formula TeCl4. The compound is volatile, subliming at 200 °C at 0.1 mmHg. Molten TeCl4 is ionic, dissociating into TeCl3+ and Te2Cl102−.

<span class="mw-page-title-main">Sulfur tetrafluoride</span> Chemical compound

Sulfur tetrafluoride is the chemical compound with the formula SF4. It is a colorless corrosive gas that releases dangerous HF upon exposure to water or moisture. Despite these unwelcome characteristics, this compound is a useful reagent for the preparation of organofluorine compounds, some of which are important in the pharmaceutical and specialty chemical industries.

<span class="mw-page-title-main">Selenium tetrafluoride</span> Chemical compound

Selenium tetrafluoride (SeF4) is an inorganic compound. It is a colourless liquid that reacts readily with water. It can be used as a fluorinating reagent in organic syntheses (fluorination of alcohols, carboxylic acids or carbonyl compounds) and has advantages over sulfur tetrafluoride in that milder conditions can be employed and it is a liquid rather than a gas.

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

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<span class="mw-page-title-main">Germanium dichloride</span> Chemical compound

Germanium dichloride is a chemical compound of germanium and chlorine with the formula GeCl2. It is a yellow solid. Germanium dichloride is an example of a compound featuring germanium in the +2 oxidation state.

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<span class="mw-page-title-main">Sulfur tetrachloride</span> Chemical compound

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<span class="mw-page-title-main">Uranium pentachloride</span> Chemical compound

Uranium pentachloride is an inorganic chemical compound composed of uranium in the +5 oxidation state and five chlorine atoms.

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<span class="mw-page-title-main">Trithiazyl trichloride</span> Chemical compound

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References

  1. Lide, David R. (1998). Handbook of Chemistry and Physics (87 ed.). Boca Raton, Florida: CRC Press. p. 487. ISBN   0-8493-0594-2 . Retrieved 2008-07-02.
  2. "323527 Selenium tetrachloride". Sigma-Aldrich. Retrieved 2008-07-02.
  3. Nowak, H. G.; Suttle, J. F.; Parker, W. E.; Kleinberg, J. (1957). "Selenium (IV) Chloride". Inorganic Syntheses. Inorganic Syntheses. Vol. 5. p. 125. doi:10.1002/9780470132364.ch33. ISBN   9780470132364.
  4. Kristallstruktur der stabilen Modifikation von SeCl4, Zeitschrift für Naturforschung, 36b, 1660, 1981
  5. Wells, Structural Inorganic Chemistry, fifth ed, Oxford, p. 709, ISBN   0-19-855370-6
  6. 1 2 Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN   978-0-08-037941-8.