Tellurophene
Chemical compound
From Wikipedia, the free encyclopedia
Tellurophene is the organotellurium compound with the formula C4H4Te. It is a heavy analogue of thiophene and selenophene. The compound is a pale yellow liquid. A number of substituted tellurophenes are known.[2]
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| Names | |||
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| Preferred IUPAC name
Tellurophene[1] | |||
| Identifiers | |||
3D model (JSmol) |
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| 103225 | |||
| ChEBI | |||
| ChemSpider | |||
| 647889 | |||
PubChem CID |
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CompTox Dashboard (EPA) |
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| Properties | |||
| C4H4Te | |||
| Molar mass | 179.68 g·mol−1 | ||
| Appearance | pale yellow | ||
| Density | 2.13 | ||
| Melting point | −36 °C (−33 °F; 237 K) | ||
| Boiling point | 148 °C (298 °F; 421 K) 714 mm Hg | ||
Refractive index (nD) |
1.6856 | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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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.[3] 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 side reactions), 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.[4][5] Hydrogen telluride (HTe-) and tellurols (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.[6] 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.[4][7]
Reactivity
Tellurophene forms poly(tellurophene) upon treatment with ferric chloride.[8]
- C4H4Te + 2 FeCl3 → 1/n[C4H2Te]n + 2 HCl + 2 FeCl2
The conversion, an oxidative polymerization, is modeled after the corresponding synthesis of polythiophene. When treated with halogens, tellurophene gives a Te(IV) derivative:
- C4H4Te + Cl2 → C4H4TeCl2
Treatment of tellurophene with tert-butyllithium gives 2-lithiotellurophene.[9]