Tantalum(IV) iodide is an inorganic compound with the chemical formula TaI4. It dissolves in water to give a green solution, but the color fades when left in the air and produces a white precipitate.[2]
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3D model (JSmol)
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| Properties | |
| TaI4 | |
| Molar mass | 688.57 |
| Appearance | black solid[1] |
| Melting point | 398 °C (671 K) (decomposes) |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Preparation
editTantalum(IV) iodide can be prepared by the reduction reaction of tantalum(V) iodide and tantalum.[2] If pyridine is used as the reducing agent, there is an adduct TaI4(py)2.[3]
Tantalum(IV) iodide can also be obtained by reacting tantalum(V) iodide with aluminum, magnesium or calcium at 380 °C. Ta6I14 is also formed. This makes it difficult to produce a very pure crystallized tantalum(IV) iodide.[4]
- 3 TaI5 + Al → 3 TaI4 + AlI3
Properties
editTantalum(IV) iodide is a black solid. It has a crystal structure isotypic to that of niobium(IV) iodide.[4] Single-crystalline tantalum(IV) iodide was first obtained in 2008 by Rafal Wiglusz and Gerd Meyer as a chance product of a reaction in a tantalum ampoule that was supposed to lead to the product Rb(Pr6C2)I12.[5] The single crystal has a triclinic crystal structure with space group P1 (space group no. 2) with two formula units per unit cell (a = 707.36 pm, b = 1064.64 pm, c = 1074.99 pm, α = 100.440°, β = 89.824° and γ = 104.392°). The crystal structure differs from that of other transition metal tetraiodides, which usually have a MI4/2I2/1 chain structure, as it consists of TaI6 octahedra bridged over a common surface to form a dimer. Two such dimers bridge over a common edge to form a tetramer.[6]
References
edit- ^ Georg Brauer: Handbuch der präparativen anorganischen Chemie. 3., umgearb. Auflage. Band III. Enke, Stuttgart 1981, ISBN 3-432-87823-0, pp. 1455.
- ^ a b Robert F. Rolsten (Jun 1958). "Preparation and X-ray Study of Some Tantalum Halides". Journal of the American Chemical Society. 80 (12): 2952–2953. doi:10.1021/ja01545a011. ISSN 0002-7863. Retrieved 2021-03-24.
- ^ R. E. McCarley, J. C. Boatman (Jun 1963). "The Preparation of Tantalum(IV) Bromide, Tantalum(IV) Iodide, and Pyridine Adducts of the Tantalum(IV) Halides". Inorganic Chemistry. 2 (3): 547–551. doi:10.1021/ic50007a030. ISSN 0020-1669. Retrieved 2021-03-24.
- ^ a b Handbuch der präparativen anorganischen Chemie. 3 (3., umgearb. Aufl ed.). Stuttgart: Enke. 1981. ISBN 978-3-432-87823-2.
- ^ Meyer, Gerd; Wiglusz, Rafal; Pantenburg, Ingo; Mudring, Anja-Verena (May 2008). "Tantalum(IV) Iodide, TaI4: A Molecular Solid Consisting of Dimers of Dimers, Ta4I16". Zeitschrift für anorganische und allgemeine Chemie (in German). 634 (5): 825–828. doi:10.1002/zaac.200700529.
- ^ Habermehl, Katja (2010). Neue Untersuchungen an Halogeniden des Niobs und Tantals (text.thesis.doctoral thesis). Universität zu Köln.