Niobium pentaiodide is the inorganic compound with the formula Nb2I10. Its name comes from the compound's empirical formula, NbI5.[1] It is a diamagnetic, yellow solid that hydrolyses readily. The compound adopts an edge-shared bioctahedral structure, which means that two NbI5 units are joined by a pair of iodide bridges. There is no bond between the Nb centres.[2] Niobium(V) chloride, niobium(V) bromide, tantalum(V) chloride, tantalum(V) bromide, and tantalum(V) iodide, all share this structural motif.
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Niobium(V) iodide
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3D model (JSmol)
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| ECHA InfoCard | 100.034.006 |
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CompTox Dashboard (EPA)
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| Properties | |
| Nb2I10 | |
| Molar mass | 1475 |
| Appearance | yellow solid |
| Density | 5.30 g/cm3 |
| Melting point | 543 °C (1,009 °F; 816 K) sublimes |
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| H314 | |
| P260, P264, P280, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P321, 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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Preparation
editNiobium pentaiodide forms from the reaction of niobium with iodine:
- 2 Nb + 5 I2 → 2 NbI5
The method used for the preparation of tantalum(V) iodide using aluminium triiodide fails to produce pure pentaiodide.[3]
Properties
editNiobium(V) iodide forms of dark, brassy, extremely moisture-sensitive needles or flakes. Its crystallises in the monoclinic crystal system with space group P21/c (space group no. 14), a = 1058 pm, b = 658 pm, c = 1388 pm, β = 109.14°. The crystal structure consists of zigzag chains of corner-sharing NbI6 octahedra. Since so far only twinned crystals of this phase have been obtained, and the structure determination is uncertain.[4] If the reaction of the elements is carried out with an excess of iodine, a triclinic modification is created with the space group P1 (No. 2), a = 759.1 pm, b = 1032.2 pm, c = 697.7 pm, α = 90 .93°, β = 116.17°, γ = 109.07°, which consists of isolated molecules Nb2I10.[3][5] This structure is isotypic with that of triclinic niobium(V) bromide.
References
edit- ^ Greenwood, N. N.; & Earnshaw, A. (1997). Chemistry of the Elements (2nd Edn.), Oxford: Butterworth-Heinemann. ISBN 0-7506-3365-4.
- ^ Krebs, Bernt; Sinram, Diethard "Darstellung, Struktur und Eigenschaften einer neuen Modifikation von NbI5 (Preparation, structure and properties of a new modification of NbI5" Zeitschrift fǔr Naturforschung, Teil B: Anorganische Chemie, Organische Chemie 1980, volume 35b, pp. 12-16.
- ^ a b G. Braurer (1963). "Niobium(V) Iodide". In G. Brauer (ed.). Handbook of Preparative Inorganic Chemistry, 2nd Ed. Vol. 1. NY, NY: Academic Press. p. 1315.
- ^ Littke, W.; Brauer, G. (Oct 1963). "Darstellung und Kristallstruktur von Niobpentajodid". Zeitschrift für anorganische und allgemeine Chemie. 325 (3–4): 122–129. doi:10.1002/zaac.19633250304. ISSN 0044-2313.
- ^ B. Krebs, D. Sinram: Darstellung, Struktur und Eigenschaften einer neuen Modifikation von NbI5. In: Zeitschrift fuer Naturforschung, Teil B. Anorganische Chemie, Organische Chemie, 1980, 35, S. 12–16.