Tellurophene is the organotellurium compound with the formula . It is a heavy analogue of thiophene and selenophene. The compound is a pale yellow liquid. A number of substituted tellurophenes are known.
Synthesis
In 1966, Mack report a synthesis of an unsubstituted tellurophene through the reaction of
sodium telluride with
diacetylene in
methanol. This method could be generalised to prepare 2,5-derivatives of tellurophene by selecting a suitably-substituted diacetylene precursor.
The product was obtained as a pale yellow liquid with a melting and boiling point of −36 °C and 148 °C, respectively. Taticchi et al. improved upon this synthesis by using a
Schlenk line to exclude oxygen and moisture from the reaction vessel, using pure butadiyne (to decrease unwanted oxidation and polymerization
), and by not using a vacuum to remove the methanol as it leads to loss of the product. This improved procedure allowed the tellurophene to be isolated in 47% yield.
Hydrogen telluride (HTe-) and
(RTeH) are implicated in these conversions.
Structure and bonding
The geometry of tellurophene was first determined in 1973 through microwave spectroscopy and has been further refined through X-ray diffraction studies.
The Te–C bond length is 2.046 Å and the C–Te–C angle is 82°. These findings are consistent with decreased
aromaticity vs that of
selenophene and related heterocycles.
Reactivity
Tellurophene forms poly(tellurophene) upon treatment with
ferric chloride.
The conversion, an oxidative polymerization, is modeled after the corresponding synthesis of
polythiophene.
When treated with halogens, tellurophene gives a Te(IV) derivative:
Treatment of tellurophene with tert-butyllithium gives 2-lithiotellurophene.
