Tellurium tetrachloride
{{chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 470478962
| Name = Tellurium tetrachloride
| ImageFile = Tellurium-tetrachloride-tetramer-from-xtal-2000-3D-balls.png
| ImageName = Tellurium tetrachloride
| IUPACName = Tellurium(IV) chloride
Tetratellurium hexadecachloride
| OtherNames = Tellurium chloride
| Section1 = {{Chembox Identifiers
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 55367
| InChI = 1/Cl4Te/c1-5(2,3)4
| InChIKey = SWLJJEFSPJCUBD-UHFFFAOYAL
| SMILES = Cl[Te](Cl)(Cl)Cl
| SMILES_Comment = monomer
| SMILES1 = [Cl+2]12[Te-2](Cl)(Cl)(Cl)3[Cl+2]4[Te-2](Cl)(Cl)(Cl)1[Cl+2]5[Te-2](Cl)(Cl)(Cl)2[Cl+2]3[Te-2]45(Cl)(Cl)(Cl)
| SMILES1_Comment = tetramer
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/Cl4Te/c1-5(2,3)4
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = SWLJJEFSPJCUBD-UHFFFAOYSA-N
| CASNo_Ref = {{cascite|changed|??}}
| CASNo = 10026-07-0
| UNII_Ref = {{fdacite|changed|FDA}}
| UNII = DNY2R5498H
| PubChem = 61443
| RTECS =
}}
| Section2 = {{Chembox Properties
| Formula = TeCl4
| MolarMass = 269.41 g/mol
| Appearance = hygroscopic pale yellow solid
(if fused, maroon liquid)
| Density = 3.26 g/cm3, solid
| Solubility = hot sulfur chloride
| MeltingPtC = 224
| BoilingPtC = 380
}}
| Section3 = {{Chembox Structure
| CrystalStruct = Monoclinic, mS80
| SpaceGroup = C12/c1, No. 15
| MolShape = Seesaw (gas phase)
| Coordination = Distorted octahedral (Te)
| Dipole = 2.59 D (gas phase)
}}
| Section7 = {{Chembox Hazards
| ExternalSDS =
| MainHazards = Toxic, corrosive,
respiratory irritant
| FlashPt =
}}
| Section8 = {{Chembox Related
| OtherAnions = Tellurium tetrafluoride
Tellurium tetrabromide
Tellurium tetraiodide
| OtherCations = Selenium tetrachloride
Polonium tetrachloride
| OtherCompounds = Tellurium dichloride
}}
}}
Tellurium tetrachloride is the inorganic compound with the empirical formula TeCl4. The compound is volatile, subliming at 200 °C at 0.1 mmHg.{{Greenwood&Earnshaw}} Molten TeCl4 is ionic, dissociating into TeCl3+ and Te2Cl102−.
Structure
TeCl4 is monomeric in the gas phase, with a structure similar to that of SF4.{{Cotton&Wilkinson6th}} In the solid state, it is a tetrameric cubane-type cluster, consisting of a Te4Cl4 core and three terminal chloride ligands for each Te. Alternatively, this tetrameric structure can be considered as a Te4 tetrahedron with face-capping chlorines and three terminal chlorines per tellurium atom, giving each tellurium atom a distorted octahedral environment
Synthesis
TeCl4 is prepared by chlorination of tellurium powder:
:Te + 2 Cl2 → TeCl4
The reaction is initiated with heat. The product is isolated by distillation.{{cite book | author = Suttle, J. F.; Smith, C. R. F. | year = 1950 | title = Inorganic Syntheses | volume = 3 | pages = 140–2 | isbn = 978-0-470-13162-6 | doi = 10.1002/9780470132340 | editor1-last = Audrieth | editor1-first = Ludwig F.}}
Crude TeCl4 can be purified by distillation under an atmosphere of chlorine.{{Cite journal |last=Petragnani |first=Nicola |last2=Mendes |first2=Samuel R. |last3=Silveira |first3=Claudio C. |date=2008-04-07 |title=Tellurium Tetrachloride: an improved method of preparation |url=https://www.sciencedirect.com/science/article/abs/pii/S0040403908003134 |journal=Tetrahedron Letters |volume=49 |issue=15 |pages=2371–2372 |doi=10.1016/j.tetlet.2008.02.085 |issn=0040-4039}}
Alternatively TeCl4 can be prepared using sulfuryl chloride (SO₂Cl₂) as a chlorine source. Yet another method involves the reaction of tellurium with sulfur monochloride (S2Cl2) at room temperature. This exothermic reaction rapidly forms white needle-like crystals of TeCl4.{{Cite journal |last=Lenher |first=Victor |title=Tellurium Tetrachloride. |url=https://pubs.acs.org/doi/pdf/10.1021/ja02016a007 |journal=Journal of the American Chemical Society|volume=24|doi=10.1021/ja02016a007}}
Reactions
Tellurium tetrachloride is the gateway compound for high valent organotellurium compounds. Arylation gives, depending on conditions, {{chem2|Te(C6H4R)2Cl2, [Te(C6H4R)5]-, [Te(C6H4R)6](2-)}}.{{cite journal |doi=10.1002/chem.200305260 |title=Syntheses and Reactions of Hexavalent Organotellurium Compounds Bearing Five or Six Tellurium-Carbon Bonds |date=2004 |last1=Miyasato |first1=Masataka |last2=Sagami |first2=Takao |last3=Minoura |first3=Mao |last4=Yamamoto |first4=Yohsuke |last5=Akiba |first5=Kin-ya |journal=Chemistry – A European Journal |volume=10 |issue=10 |pages=2590–2600 |pmid=15146530 }}
TeCl4 has few applications in organic synthesis. Its equivalent weight is high, and the toxicity of organotellurium compounds is problematic. Possible applications of tellurium tetrachloride to organic synthesis have been reported.{{cite journal |last1=Petragnani |first1= N. |last2=Comasseto |first2=J. V. |title= Tellurium Reagents in Organic Synthesis; Recent Advances. Part 1 |journal=Synthesis |volume= 1991 |year=1991 |issue=10 |pages=793–817 |doi=10.1055/s-1991-26577|s2cid= 260335920 }} and {{cite journal |last1=Petragnani |first1= N. |last2=Comasseto |first2=J. V. |title= Tellurium Reagents in Organic Synthesis; Recent Advances. Part 2 |journal=Synthesis |volume= 1991 |year=1991 |issue=11 |pages=897–919 |doi=10.1055/s-1991-26605|s2cid= 196716602 }} It adds to alkenes to give Cl-C-C-TeCl3 derivatives, wherein the Te can be subsequently removed with sodium sulfide. Electron-rich arenes react to give aryl Te compounds. Thus, anisole gives TeCl2(C6H4OMe)2, which can be reduced to the diaryl telluride. TeCl4 is a precursor to tellurium-containing heterocycles like tellurophenes.
Heating a mixture of TeCl4 and metallic tellurium gives tellurium dichloride (TeCl2).
In moist air, TeCl4 forms tellurium oxychloride (TeOCl2), which further decomposes with excess water to form tellurous acid (H2TeO3).{{Cite journal |last=Simons |first=J. H. |date=1930-09-01 |title=The Properties of Tellurium Tetrachloride |url=https://pubs.acs.org/doi/epdf/10.1021/ja01372a003?ref=article_openPDF. |journal=Journal of the American Chemical Society |volume=52 |issue=9 |pages=3488–3493 |doi=10.1021/ja01372a003 |issn=0002-7863}}
Safety considerations
References
{{Tellurium compounds}}
{{Chlorides}}
Category:Tellurium(IV) compounds