Tellurophene
{{Chembox
| Name = Tellurophene
| ImageFile = Tellurophene.png
| ImageSize = 110 px
| ImageFileL1 = Tellurophene-3D-balls.png
| ImageFileR1 = Tellurophene-3D-vdW.png
| PIN = Tellurophene{{cite book |author=International Union of Pure and Applied Chemistry |date=2014 |title=Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013 |publisher=The Royal Society of Chemistry |pages=883 |doi=10.1039/9781849733069 |isbn=978-0-85404-182-4}}
| OtherNames =
| Section1 = {{Chembox Identifiers
| ChemSpiderID = 119908
| PubChem = 136131
| CASNo = 288-08-4
| ChEBI = 30858
| Beilstein = 103225
| Gmelin = 647889
| StdInChI=1S/C4H4Te/c1-2-4-5-3-1/h1-4H
| StdInChIKey = TULWUZJYDBGXMY-UHFFFAOYSA-N
| SMILES = C1=C[Te]C=C1
}}
| Section2 = {{Chembox Properties
|C=4|H=4|Te=1
| MolarMass =
| RefractIndex = 1.6856
| Appearance = pale yellow
| Density = 2.13
| MeltingPtC = -36
| MeltingPt_notes =
| BoilingPtC = 148
| BoilingPt_notes = 714 mm Hg
| Solubility =
}}
| Section3 =
| Section4 =
| Section5 =
| Section6 =
}}
Tellurophene is the organotellurium compound with the formula {{chem2|C4H4Te}}. It is a heavy analogue of thiophene and selenophene. The compound is a pale yellow liquid. A number of substituted tellurophenes are known.{{Cite journal|last1=Karapala|first1=Vamsi Krishna|last2=Shih|first2=Hong-Pin|last3=Han|first3=Chien-Chung|year=2018|title=Cascade and Effective Syntheses of Functionalized Tellurophenes|journal=Organic Letters|volume=20|issue=6|pages=1550–1554|doi=10.1021/acs.orglett.8b00279|pmid=29494165|issn=1523-7060}}
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.{{Cite journal|last = Mack|first = W.|title = Synthesis of Tellurophene and its 2,5-Disubstituted Derivatives|journal = Angew. Chem. Int. Ed.|volume = 5|issue = 10|page = 896|doi = 10.1002/anie.196608961|year = 1966}} 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.{{cite journal|title = Tellurophen and some of its derivatives|first1 = Francesco|last1 = Fringuelli|first2 = Aldo|last2 = Taticchi|journal = Journal of the Chemical Society, Perkin Transactions 1|doi = 10.1039/P19720000199|year = 1972|pages = 199–203}} 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.{{Cite journal|last1=Lukevics|first1=E.|last2=Arsenyan|first2=P.|last3=Belyakov|first3=S.|last4=Pudova|first4=O.|year=2002|title=Molecular Structure of Selenophenes and Tellurophenes|journal=Chemistry of Heterocyclic Compounds|volume=38|issue=7|pages=763–777|doi=10.1023/a:1020607300418|s2cid=92305752 |issn=0009-3122}} 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.{{cite book|series = Advances in Heterocyclic Chemistry|volume = 21|year = 1977|pages = 119–173|first1 = Francesco|last1 = Fringuelli|first2 = Gianlorenzo|last2 = Marino|first3 = Aldo|last3 = Taticchi| title=Advances in Heterocyclic Chemistry Volume 21 | chapter=Tellurophene and Related Compounds |doi = 10.1016/S0065-2725(08)60731-X|isbn = 9780120206216|chapter-url = https://books.google.com/books?id=1qIOmeTdiGcC&pg=PA119}}{{cite journal|title = A comparative study of the aromatic character of furan, thiophen, selenophen, and tellurophen|first1 = Francesco|last1 = Fringuelli|first2 = Gianlorenzo|last2 = Marino|first3 = Aldo|last3 = Taticchi|first4 = Giuliano|last4 = Grandolini|journal = Journal of the Chemical Society, Perkin Transactions 2|year = 1974|doi = 10.1039/P29740000332|volume = 1974|issue = 4|pages = 332–337}}
Reactivity
Tellurophene forms poly(tellurophene) upon treatment with ferric chloride.{{cite journal |doi=10.1143/JJAP.24.L425 |title=Preparation and Property of Polytellurophene and Polyselenophene |date=1985 |last1=Sugimoto |first1=Ryu-Ichi |last2=Yoshino |first2=Katsumi |last3=Inoue |first3=Shigehito |last4=Tsukagoshi |first4=Kunimitsu |journal=Japanese Journal of Applied Physics |volume=24 |issue=6A |pages=L425 |bibcode=1985JaJAP..24L.425S }}
:{{chem2|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:
:{{chem2|C4H4Te + Cl2 -> C4H4TeCl2}}
Treatment of tellurophene with tert-butyllithium gives 2-lithiotellurophene.{{cite journal |doi=10.1002/anie.201005664 |title=Polytellurophenes with Properties Controlled by Tellurium-Coordination |date=2010 |last1=Jahnke |first1=Ashlee A. |last2=Howe |first2=Graeme W. |last3=Seferos |first3=Dwight S. |journal=Angewandte Chemie International Edition |volume=49 |issue=52 |pages=10140–10144 |pmid=21105034 }}