Organotellurium chemistry describes the synthesis and properties of organotellurium compounds,
chemical compounds containing a
carbon-
telluriumchemical bond. Organotellurium chemistry is a lightly studied area, in part because of it having few applications.[1][2]
Functional groups
The tellurium analogues of common
organosulfur and
organoselenium functional groups are known.
Tellurols 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 organotellurium(IV) compounds are well developed: R4−xTeClx and the
telluroxides (R2TeO).
Synthesis and reactions
Reduced organotellurium compounds
Reduced organotellurium 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 reagents and Te:
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.[5] It reacts with arenes to give aryltellurium trichlorides:[6]
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
dimeric structures, reflecting the
Lewis acidity of the Te(IV) center. The dimers are cleaved by halides and other Lewis bases:[7]
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.[6]
Hexamethylpertellurane was prepared by oxidation of tetramethyltellurium with
xenon difluoride.[9] The resulting TeF2(CH3)4 is then treated
dimethylzinc:
Te(CH3)4 + XeF2 → Te(CH3)4F2 + Xe
Te(CH3)4F2 + Zn(CH3)2 → Te(CH3)6 + ZnF2
The octahedral compounds TeAr6 have also been prepared.[10]
Applications
Dimethyl telluride is used to in
metalorganic vapour phase epitaxy where it serves as a volatile source of Te. It is the only organotellurium compound that has been quantified in environmental samples.[11]
References
^Nicola Petragnani, Tellurium in Organic Synthesiss 1994, Academic Press, New York.
ISBN0-12-552810-8
^M. Detty, M. O'Regan, Tellurium-Containing Heterocycles., John Wiley & Sons, Inc., New York, 1994ISBN0-471-63395-X
^Nobuaki Kambe, Toru Inoue, Noboru Sonoda (1995). "Generation of N,N-Diethylcarbamoyllithium Via Lithium-Tellurium Exchange and Its Reaction with 3-Phenylpropanal: N,N-Diethyl-2-Hydroxy-4-Phenylbutanamide". Organic Syntheses. 72: 154.
doi:
10.15227/orgsyn.072.0154.{{
cite journal}}: CS1 maint: multiple names: authors list (
link)
^Palladium- and copper-catalyzed cross-coupling and carbonylative cross-coupling of organotellurium compounds with organostannanes (
Chem. Commun.1999, 2117) - Royal Society of Chemistry Suk-Ku Kang, Sang-Woo Lee and Hyung-Chul Ryu
Link
^Ahmed, Latif; Morrison, John A. (1990). "Synthesis and characterization of hexamethyltellurium(VI)". J. Am. Chem. Soc.112 (20): 7411–7413.
doi:
10.1021/ja00176a061.
^Miyasato, Masataka; Sagami, Takao; Minoura, Mao; Yamamoto, Yohsuke; Akiba, Kin-ya (2004). "Syntheses and Reactions of Hexavalent Organotellurium Compounds Bearing Five or Six Tellurium-Carbon Bonds". Chemistry – A European Journal. 10 (10): 2590–2600.
doi:
10.1002/chem.200305260.
PMID15146530.
^Wallschläger, D.; Feldmann, F. (2010). Formation, Occurrence, Significance, and Analysis of Organoselenium and Organotellurium Compounds in the Environment. Metal Ions in Life Sciences. Vol. 7, Organometallics in Environment and Toxicology. RSC Publishing. pp. 319–364.
ISBN978-1-84755-177-1.