The telluride

ion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conven ...

is the

anion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

Te²⁻ and its derivatives. It is analogous to the other chalcogenide anions, the lighter O²⁻, S²⁻, and Se²⁻, and the heavier Po²⁻. In principle, Te²⁻ is formed by the two-e⁻ reduction of

tellurium Tellurium is a chemical element with the symbol Te and atomic number 52. It is a brittle, mildly toxic, rare, silver-white metalloid. Tellurium is chemically related to selenium and sulfur, all three of which are chalcogens. It is occasionally fou ...

. The

redox potential Redox potential (also known as oxidation / reduction potential, ''ORP'', ''pe'', ''E_'', or E_) is a measure of the tendency of a chemical species to acquire electrons from or lose electrons to an electrode and thereby be reduced or oxidised respe ...

is −1.14 V. :Te(s) + 2 e⁻ ↔ Te²⁻ Although solutions of the telluride dianion have not been reported, soluble salts of bitelluride (TeH⁻) are known.

Organic tellurides

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

methylation In the chemical sciences, methylation denotes the addition of a methyl group on a substrate, or the substitution of an atom (or group) by a methyl group. Methylation is a form of alkylation, with a methyl group replacing a hydrogen atom. These t ...

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 to

ether In organic chemistry, ethers are a class of compounds that contain an ether group—an oxygen atom connected to two alkyl or aryl groups. They have the general formula , where R and R′ represent the alkyl or aryl groups. Ethers can again be c ...

s with tellurium replacing oxygen, 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°.

Inorganic tellurides

Many metal tellurides are known, including some telluride minerals. These include natural gold tellurides, like

calaverite Calaverite, or gold telluride, is an uncommon telluride of gold, a metallic mineral with the chemical formula AuTe2, with approximately 3% of the gold replaced by silver. It was first discovered in Calaveras County, California in 1861, and was ...

and krennerite (AuTe₂), and

sylvanite Sylvanite or silver gold telluride, chemical formula , is the most common telluride of gold. Properties The gold:silver ratio varies from 3:1 to 1:1. It is a metallic mineral with a color that ranges from a steely gray to almost white. It is c ...

(AgAuTe₄). They 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 Aurostibite is an isometric gold antimonide mineral which is a member of the pyrite group. Aurostibite was discovered in 1952 and can be found in hydrothermal gold-quartz veins, in sulfur-deficient environments that contain other antimony mineral ...

(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⁻. Catenated Te anions are known in the form of the

polytelluride In chemistry, a polytelluride usually refers to anions of the formula (Ten)2-. Many main group and transition metals form complexes with polytelluride anions. Preparation Conceptually, polytellurides are derived from polytelluranes H2Ten, but ...

s. They arise by the reaction of telluride dianion with elemental Te: :Te^2- + n Te → Te_n+1^2-

Applications

Tellurides have no large scale applications. Cadmium telluride has attractive

photovoltaic Photovoltaics (PV) is the conversion of light into electricity using semiconducting materials that exhibit the photovoltaic effect, a phenomenon studied in physics, photochemistry, and electrochemistry. The photovoltaic effect is commercially us ...

properties. Both

bismuth telluride Bismuth telluride (Bi2Te3) is a gray powder that is a compound of bismuth and tellurium also known as bismuth(III) telluride. It is a semiconductor, which, when alloyed with antimony or selenium, is an efficient thermoelectric material for refriger ...

and lead telluride are exceptional thermoelectric materials. Some of these thermoelectric materials have been commercialized.

References

Anions {{Inorganic-compound-stub