Tritellurium dichloride

Tritellurium dichloride
Identifiers
CAS Number	12526-08-8 ;
Properties
Chemical formula	Te3Cl2
Molar mass	453.71 g/mol
Hazards
EU classification (DSD) (outdated)	not listed
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
	(what is ?)
	Infobox references

Tritellurium dichloride is the inorganic compound with the formula Te₃Cl₂. It is one of the more stable lower chlorides of tellurium.

Structure of trans-[TeCl₂(SC(NMe₂)₂)₂] (H atoms omitted).[1]

Preparation and properties

Te₃Cl₂ is a gray solid. Its structure consists of a long chain of Te atoms, with every third Te center carrying two chloride ligands for the repeat unit -Te-Te-TeCl₂-.[2] It is a semiconductor with a band gap of 1.52 eV, which is larger than that for elemental Te (0.34 eV).[3] It is prepared by heating Te with the appropriate stoichiometry of chlorine.[4]

Other lower tellurium chlorides

Te₂Cl₂ is a yellow liquid prepared by reaction of lithium polytellurides with TeCl₄. Te₂Cl, also a polymer, is a metastable gray solid, tending to convert to Te₃Cl₂ and TeCl₄.[3] Being unstable with respect to disproportionation, tellurium dichloride has not been isolated as a solid, but has been characterised as the main component of the vapor formed with TeCl₄ and hot Te.[5]

Although TeCl₂ has not been isolated, its complexes are well characterized. They are prepared by treating tellurium dioxide with hydrochloric acid in the presence of thioureas. The thiourea serves both as a ligand and as a reductant, converting Te(IV) to Te(II).

References

O. Foss, K. Maartmann-Moe (1986). "Crystal and Molecular Structures of trans Square-Planar Complexes of Tellurium Dichloride, Dibromide and Diiodide with Tetramethylthiourea, TeL₂X₂. Bond Lengths in Centrosymmetric Tellurium(II) Complexes". Acta Chemica Scandinavica A. 40: 675. doi:10.3891/acta.chem.scand.40a-0675.CS1 maint: uses authors parameter (link)
Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
Zhengtao Xu "Recent Developments in Binary Halogen–Chalcogen Compounds, Polyanions and Polycations" in Handbook of Chalcogen Chemistry: New Perspectives in Sulfur, Selenium and Tellurium, Francesco Devillanova, Editor, 2006, RSC. pp. 381-416. Royal Society doi:10.1039/9781847557575-00455
R. Kniep, D. Mootz, A. Rabenau "Zur Kenntnis der Subhalogenide des Tellurs" Zeitschrift für anorganische und allgemeine Chemie 1976, Volume 422, pages 17–38. doi:10.1002/zaac.19764220103
Liv Fernholt, Arne Haaland , Hans V. Volden, Rüdiger Kniep "The molecular structure of tellurium dichloride, TeCl₂, determined by gas electron diffraction" Journal of Molecular Structure 1985, volume 128, pages 29-31.doi:10.1016/0022-2860(85)85037-7

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[1] O. Foss, K. Maartmann-Moe (1986). "Crystal and Molecular Structures of trans Square-Planar Complexes of Tellurium Dichloride, Dibromide and Diiodide with Tetramethylthiourea, TeL₂X₂. Bond Lengths in Centrosymmetric Tellurium(II) Complexes". Acta Chemica Scandinavica A. 40: 675. doi:10.3891/acta.chem.scand.40a-0675.CS1 maint: uses authors parameter (link)

[2] Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.

[Xu-3] Zhengtao Xu "Recent Developments in Binary Halogen–Chalcogen Compounds, Polyanions and Polycations" in Handbook of Chalcogen Chemistry: New Perspectives in Sulfur, Selenium and Tellurium, Francesco Devillanova, Editor, 2006, RSC. pp. 381-416. Royal Society doi:10.1039/9781847557575-00455

[4] R. Kniep, D. Mootz, A. Rabenau "Zur Kenntnis der Subhalogenide des Tellurs" Zeitschrift für anorganische und allgemeine Chemie 1976, Volume 422, pages 17–38. doi:10.1002/zaac.19764220103

[5] Liv Fernholt, Arne Haaland , Hans V. Volden, Rüdiger Kniep "The molecular structure of tellurium dichloride, TeCl₂, determined by gas electron diffraction" Journal of Molecular Structure 1985, volume 128, pages 29-31.doi:10.1016/0022-2860(85)85037-7