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Tellurium tetraiodide

Names
Other names tellurium(IV) iodide
Identifiers
CAS Number	7790-48-9
3D model (JSmol)	Interactive image
ChemSpider	74232
ECHA InfoCard	100.029.282
EC Number	232-210-5
PubChem CID	82255
UNII	ZB48I033V5
CompTox Dashboard (EPA)	DTXSID1064877
InChI InChI=1S/I4Te/c1-5(2,3)4Key: XCOKHDCPVWVFKS-UHFFFAOYSA-N
SMILES (I)(I)(I)I
Properties
Chemical formula	TeI4
Molar mass	635.218 g/mol
Appearance	black crystals
Density	5.05 g/cm, solid
Melting point	280 °C (536 °F; 553 K)
Structure
Crystal structure	orthorhombic
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H302, H312, H314, H332
Precautionary statements	P260, P261, P264, P270, P271, P280, P301+P312, P301+P330+P331, P302+P352, P303+P361+P353, P304+P312, P304+P340, P305+P351+P338, P310, P312, P322, P330, P363, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). Y verify (what is  ?) Infobox references

Tellurium tetraiodide (TeI₄) is an inorganic chemical compound. It has a tetrameric structure which is different from the tetrameric solid forms of TeCl₄ and TeBr₄. In TeI₄ the Te atoms are octahedrally coordinated and edges of the octahedra are shared.

Preparation

Tellurium tetraiodide can be prepared by reacting Te and iodomethane, CH₃I. In the vapour TeI₄ dissociates:

TeI₄ → TeI₂ + I₂

It can be also obtained by reacting telluric acid with hydrogen iodide.

Te(OH)₆ + HI → TeI₄ + I₂ + 6 H₂O

It can also be obtained by reacting the elements, which can also produce tellurium diiodide and tellurium monoiodide, depending on the reaction conditions:

Te + 2 I₂ → TeI₄

TeI₄ → TeI₂ + I₂

Properties

Tellurium tetraiodide is an iron-gray solid that decomposes slowly in cold water and quickly in warm water to form tellurium dioxide and hydrogen iodide. It is stable even in moist air and decomposes when heated, releasing iodine. It is soluble in hydriodic acid to form H and it is slightly soluble in acetone.

Tellurium tetraiodide is a conductor when molten, dissociating into the ions TeI₃ and I. In solvents with donor properties such as acetonitrile, CH₃CN ionic complexes are formed which make the solution conducting:

TeI₄ + 2 CH₃CN → (CH₃CN)₂TeI₃ + I

Five modifications of tellurium tetraiodide are known, all of which are composed of tetrameric molecules. The δ form is the most thermodynamically stable form. This is structurally derived (as well as the α, β and γ forms) from the ε form.

References

1. "Tellurium tetraiodide". pubchem.ncbi.nlm.nih.gov. Retrieved 13 December 2021.
2. ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
3. ^ Inorganic Chemistry,Egon Wiberg, Arnold Frederick Holleman Elsevier 2001 ISBN 0-12-352651-5
4. ^ Handbuch der präparativen anorganischen Chemie. 1 (3., umgearb. Aufl ed.). Stuttgart: Enke. 1975. p. 435. ISBN 978-3-432-02328-1.
5. Hagen, A. P. (2009-09-17). Inorganic Reactions and Methods, The Formation of Bonds to Halogens (Part 1). John Wiley & Sons. ISBN 978-0-470-14538-8.
6. Tellurium(IV) iodide, 99% (metals basis) at AlfaAesar, accessed on 2013-12-17 (PDF) (JavaScript required).
7. Riedel, Erwin; Janiak, Christoph (2011). Anorganische Chemie: Zusatzmaterial online. Studium (8. Aufl ed.). Berlin: de Gruyter. ISBN 978-3-11-022567-9.

• Iodides
• Tellurium halides
• Tellurium(IV) compounds
• Chalcohalides