Tellurium tetrachloride
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| Names | |
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| IUPAC names
Tellurium(IV) chloride
Tetratellurium hexadecachloride | |
| Other names
Tellurium chloride
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| Identifiers | |
3D model (JSmol)
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| ChemSpider | |
| ECHA InfoCard | 100.030.038 |
PubChem CID
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| UNII | |
CompTox Dashboard (EPA)
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| Properties | |
| TeCl4 | |
| Molar mass | 269.41 g/mol |
| Appearance | hygroscopic pale yellow solid (if fused, maroon liquid) |
| Density | 3.26 g/cm3, solid |
| Melting point | 224 °C (435 °F; 497 K) |
| Boiling point | 380 °C (716 °F; 653 K) |
| hot sulfur chloride[1] | |
| Structure | |
| Monoclinic, mS80 | |
| C12/c1, No. 15 | |
| Distorted octahedral (Te) | |
| Seesaw (gas phase) | |
| 2.59 D (gas phase) | |
| Hazards | |
| Occupational safety and health (OHS/OSH): | |
Main hazards
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Toxic, corrosive, respiratory irritant |
| Related compounds | |
Other anions
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Tellurium tetrafluoride Tellurium tetrabromide Tellurium tetraiodide |
Other cations
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Selenium tetrachloride Polonium tetrachloride |
Related compounds
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Tellurium dichloride |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Tellurium tetrachloride is the inorganic compound with the empirical formula TeCl4. The compound is volatile, subliming at 200 °C at 0.1 mmHg.[2] Molten TeCl4 is ionic, dissociating into TeCl3+ and Te2Cl102−.[2]
Structure
[edit]TeCl4 is monomeric in the gas phase, with a structure similar to that of SF4.[3] 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
[edit]TeCl4 is prepared by chlorination of tellurium powder:
- Te + 2 Cl2 → TeCl4
The reaction is initiated with heat. The product is isolated by distillation.[4] Crude TeCl4 can be purified by distillation under an atmosphere of chlorine.[1]
Alternatively TeCl4 can be prepared using sulfuryl chloride (SO₂Cl₂) as a chlorine source.[1] 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.[5]
Reactions
[edit]Tellurium tetrachloride is the gateway compound for high valent organotellurium compounds. Arylation gives, depending on conditions, Te(C6H4R)2Cl2, [Te(C6H4R)5]−, [Te(C6H4R)6]2−.[6]
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.[7] 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.[1]
Heating a mixture of TeCl4 and metallic tellurium gives tellurium dichloride (TeCl2).[8]
In moist air, TeCl4 forms tellurium oxychloride (TeOCl2), which further decomposes with excess water to form tellurous acid (H2TeO3).[8]
Safety considerations
[edit]As is the case for other tellurium compounds, TeCl4 is toxic. It also releases HCl upon hydrolysis.[1]
References
[edit]- ^ a b c d e Petragnani, Nicola; Mendes, Samuel R.; Silveira, Claudio C. (2008-04-07). "Tellurium Tetrachloride: an improved method of preparation". Tetrahedron Letters. 49 (15): 2371–2372. doi:10.1016/j.tetlet.2008.02.085. ISSN 0040-4039.
- ^ a b Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
- ^ Cotton, F. Albert; Wilkinson, Geoffrey; Murillo, Carlos A.; Bochmann, Manfred (1999), Advanced Inorganic Chemistry (6th ed.), New York: Wiley-Interscience, ISBN 0-471-19957-5
- ^ Suttle, J. F.; Smith, C. R. F. (1950). Audrieth, Ludwig F. (ed.). Inorganic Syntheses. Vol. 3. pp. 140–2. doi:10.1002/9780470132340. ISBN 978-0-470-13162-6.
{{cite book}}: CS1 maint: multiple names: authors list (link) - ^ Lenher, Victor. "Tellurium Tetrachloride". Journal of the American Chemical Society. 24. doi:10.1021/ja02016a007.
- ^ 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. PMID 15146530.
- ^ Petragnani, N.; Comasseto, J. V. (1991). "Tellurium Reagents in Organic Synthesis; Recent Advances. Part 1". Synthesis. 1991 (10): 793–817. doi:10.1055/s-1991-26577. S2CID 260335920. and Petragnani, N.; Comasseto, J. V. (1991). "Tellurium Reagents in Organic Synthesis; Recent Advances. Part 2". Synthesis. 1991 (11): 897–919. doi:10.1055/s-1991-26605. S2CID 196716602.
- ^ a b Simons, J. H. (1930-09-01). "The Properties of Tellurium Tetrachloride". Journal of the American Chemical Society. 52 (9): 3488–3493. doi:10.1021/ja01372a003. ISSN 0002-7863.