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.[2] In TeI4 the Te atoms are octahedrally coordinated and edges of the octahedra are shared.[2]
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Other names
tellurium(IV) iodide
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ECHA InfoCard | 100.029.282 |
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CompTox Dashboard (EPA)
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Properties | |
TeI4 | |
Molar mass | 635.218 g/mol |
Appearance | black crystals |
Density | 5.05 g/cm3, solid |
Melting point | 280 °C (536 °F; 553 K) |
Structure | |
orthorhombic | |
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GHS labelling:[1] | |
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H302, H312, H314, H332 | |
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 [77 °F], 100 kPa).
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Infobox references
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Tellurium tetraiodide can be prepared by reacting Te and iodomethane, CH3I.[2] In the vapour TeI4 dissociates:[3]
It can be also obtained by reacting telluric acid with hydrogen iodide.[4]
It can also be obtained by reacting the elements, which can also produce tellurium diiodide and tellurium monoiodide, depending on the reaction conditions:[5]
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.[6] It is stable even in moist air and decomposes when heated, releasing iodine. It is soluble in hydriodic acid to form H[TeI5] and it is slightly soluble in acetone.[4]
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:[3]
Five modifications of tellurium tetraiodide are known, all of which are composed of tetrameric molecules.[7] 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.