Organotellurium chemistry describes the synthesis and properties of

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one elemen ...

s containing a carbon-

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 ...

chemical bond A chemical bond is a lasting attraction between atoms or ions that enables the formation of molecules and crystals. The bond may result from the electrostatic force between oppositely charged ions as in ionic bonds, or through the sharing of ...

. Organotellurium chemistry is a lightly studied area, in part because of the few applications.

Functional groups

The Te analogues of common

organosulfur Organosulfur compounds are organic compounds that contain sulfur. They are often associated with foul odors, but many of the sweetest compounds known are organosulfur derivatives, e.g., saccharin. Nature abounds with organosulfur compounds—sulfur ...

and

organoselenium Organoselenium compounds (or seleno-organic) are chemical compounds containing carbon-to- selenium chemical bonds. Organoselenium chemistry is the corresponding science exploring their properties and reactivity. Selenium belongs with oxygen and su ...

functional groups are known.

Tellurol Tellurols are analogues of alcohols and phenols where tellurium replaces oxygen. Tellurols, selenols, and thiols have similar properties, but tellurols are the least stable. Although they are fundamental representatives of organotellurium compounds ...

s are however unstable with respect to oxidation to the ditellurides. Commonly encountered organotellurium compounds are diorganomono- and ditellurides, R₂Te and (RTe)₂, respectively. Two other families of organoTe(IV) compounds are well developed: R_4−xTeCl_x and the

telluroxide A telluroxide is a type of organotellurium compound with the formula R2TeO. These compounds are analogous to sulfoxides in some respects. Reflecting the decreased tendency of Te to form multiple bonds, telluroxides exist both the monomer and the p ...

s (R₂TeO).

Synthesis and reactions

Reduced organoTe compounds

Reduced organoTe compounds are commonly obtained from NaHTe and lithium telluride: :Li₂Te + 2 RBr → R₂Te + 2 LiBr A direct route to organolithium compounds starts from reactions of organolithium or

Grignard reagent A Grignard reagent or Grignard compound is a chemical compound with the general formula , where X is a halogen and R is an organic group, normally an alkyl or aryl. Two typical examples are methylmagnesium chloride and phenylmagnesium bromide . ...

s and Te: :Te + ArLi → ArTeLi

Butyl lithium Butyllithium may refer to one of 5 isomeric organolithium reagents of which 3 are commonly used in chemical synthesis: * ''n''-Butyllithium, abbreviated BuLi or nBuLi * ''sec''-Butyllithium, abbreviated ''sec''-BuLi or sBuLi, has 2 stereoisomers, ...

gives the telluride similarly: :Te + BuLi → BuTeLi Organotelluride anions can be oxidized or alkylated: :2 RTeLi + 0.5 O₂ + H₂O → RTeTeR + 2 LiOH :RTeLi + R'Br → RTeR' + LiBr Diorganoditellurides are valued intermediates, especially the aryl derivatives such as diphenyl ditelluride: :Ar₂Te₂ + RLi → RTeAr + LiTeR :Ph₂Te₂ + 2 Li → 2 LiTePh

Derivatives of TeCl₄

One departure from sulfur and selenium chemistry is the availability of the tetrachloride, TeCl₄. It reacts with arenes to give aryltellurium trichlorides: :ArH + TeCl₄ → ArTeCl₃ + HCl For electron-rich arenes, the disubstitution occurs :ArH + ArTeCl₃ → Ar₂TeCl₂ → + HCl Tellurium tetrachloride adds across alkenes and alkynes to the chloro tellurium trichlorides: :RCH=CH₂ + TeCl₄ → RCH(Cl)-CH₂TeCl₃ Organotellurium trichlorides adopt

dimer Dimer may refer to: * Dimer (chemistry), a chemical structure formed from two similar sub-units ** Protein dimer, a protein quaternary structure ** d-dimer * Dimer model, an item in statistical mechanics, based on ''domino tiling'' * Julius Dimer ( ...

ic structures, reflecting the

Lewis acid A Lewis acid (named for the American physical chemist Gilbert N. Lewis) is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct. A Lewis base, then, is any sp ...

ity of the Te(IV) center. The dimers are cleaved by halides and other Lewis bases: :RTeCl₃ + Cl⁻ → RTeCl₄⁻ The anions RTeCl₄⁻ (and the related adducts RTeCl₃L) adopt square pyramidal structures with the electronegative groups in the plane. Organotellurium(IV) chlorides are susceptible to substitution reactions where by chloride is replaced by other halides and pseudohalides. The TeClx group can also be removed with Raney nickel. OrganoTe(IV) compounds participate in Stille reactions: :

Telluroxides

Telluroxides are generally related to

sulfoxide In organic chemistry, a sulfoxide, also called a sulphoxide, is an organosulfur compound containing a sulfinyl () functional group attached to two carbon atoms. It is a polar functional group. Sulfoxides are oxidized derivatives of sulfides. E ...

s and

selenoxide Organoselenium compounds (or seleno-organic) are chemical compounds containing carbon-to- selenium chemical bonds. Organoselenium chemistry is the corresponding science exploring their properties and reactivity. Selenium belongs with oxygen and su ...

s in terms of their structures. Unlike their lighter analogues however, they polymerize (reversibly) when crystallized. Analogous to selenoxide oxidation, allylic

s undergo ,3

sigmatropic rearrangement A sigmatropic reaction in organic chemistry is a pericyclic reaction wherein the net result is one sigma bond, σ-bond is changed to another σ-bond in an uncatalyzed intramolecular reaction. The name ''sigmatropic'' is the result of a compound wor ...

s forming allylic alcohols after hydrolysis. Also analogous to the

selenoxide elimination Selenoxide elimination (also called α-selenation) is a method for the chemical synthesis of alkenes from selenoxides. It is most commonly used to synthesize α,β-unsaturated carbonyl compounds from the corresponding saturated analogues. It is mec ...

, certain telluroxides give

alkene In organic chemistry, an alkene is a hydrocarbon containing a carbon–carbon double bond. Alkene is often used as synonym of olefin, that is, any hydrocarbon containing one or more double bonds.H. Stephen Stoker (2015): General, Organic ...

s upon heating.

Applications

Dimethyl telluride is used to in

metalorganic vapour phase epitaxy Metalorganic vapour-phase epitaxy (MOVPE), also known as organometallic vapour-phase epitaxy (OMVPE) or metalorganic chemical vapour deposition (MOCVD), is a chemical vapour deposition method used to produce single- or polycrystalline thin films. ...

where it serves as a volatile source of Te. It is the only organotellurium compound that has been quantified in environmental samples.

References

{{Authority control