Telluride (chemistry)

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Telluride
Identifiers
ChemSpider 19241429 YesY
Jmol-3D images Image 1
Properties
Molecular formula Te2−
Molar mass 127.6 g mol-1
Related compounds
Other anions Sulfide, Selenide
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

The telluride ion is the anion Te2− and its derivatives. Telluride is member of the sixth period of the periodic table, containing the dianions O2−, S2−, and Se2− (see chalcogenide).[1]

The telluride anion is formed from the reduction of the tellurium metal. The redox potential of pure Te metal is fairly negative, -1.14 V.[2]

Te(s) + 2 e- ↔ Te2-

The acid hydride of tellurium, hydrogen telluride, H2Te, is unstable compound that decomposes to tellurium metal. It is strongly acidic, dissociating into hydrogen telluride ion (HTe-) in aqueous solutions. Like its sulfide and selenide counterparts, the Te2- anion only exists in aqueous solutions in basic conditions.

Organic tellurides[edit]

Tellurides also describe a class of organotellurium compounds formally derived from Te2−. An illustrative member is dimethyl telluride, which results from the methylation of telluride salts:

2 CH3I + Na2Te → (CH3)2Te + 2 NaI

Dimethyl telluride is formed by the body when tellurium is ingested . Such compounds are often called telluroethers because they are structurally related although the length of the C-Te bond is much longer than a C-O bond. C-Te-C angles tend to be closer to 90°.[3]

Inorganic tellurides[edit]

Many metal tellurides are known, including some telluride minerals. These include natural gold tellurides, like calaverite and krennerite (AuTe2), and sylvanite (AgAuTe4). Commercially, the tellurides are minor ores of gold, although they comprise the major naturally-occurring compounds of gold. (A few other natural compounds of gold, such as the bismuthide maldonite (Au2Bi) and antimonide aurostibite (AuSb2), are known).Although the bonding in such materials is often fairly covalent, they are described casually as salts of Te2−. Using this approach, Ag2Te is derived from Ag+ and Te2-.

Tellurides do not have any great economic importance. Cadmium telluride does however have photovoltaic properties, and both bismuth telluride and lead telluride are exceptional thermoelectric materials, although not commercialized.[4]

References[edit]

  1. ^ Greenwood, N. N.; & Earnshaw, A. (1997). Chemistry of the Elements (2nd Edn.), Oxford:Butterworth-Heinemann. ISBN 0-7506-3365-4.
  2. ^ "Standard Reduction Potentials, Indiana University.
  3. ^ Reid, G., et al. Journal of Organometallic Chemistry, 642 (2002) 186– 190.
  4. ^ "The Thespian Catalyst", David Saltzberg

See category for a list.