Iridium hexafluoride, also iridium(VI) fluoride, (IrF6) is a compound of iridium and fluorine and one of the seventeen known binary hexafluorides. It is one of only a few compounds with iridium in the oxidation state +6.
Synthesis
Iridium hexafluoride is made by a direct reaction of iridium metal in an excess of elemental fluorine gas at 300 °C. However, it is thermally unstable and must be frozen out of the gaseous reaction mixture to avoid dissociation.
- Ir + 3 F
2 → IrF
6
Description
Iridium hexafluoride is a yellow crystalline solid that melts at 44 °C and boils at 53.6 °C.[1] The solid structure measured at −140 °C is orthorhombic space group Pnma. Lattice parameters are a = 9.411 Å, b = 8.547 Å, and c = 4.952 Å. There are four formula units (in this case, discrete molecules) per unit cell, giving a density of 5.11 g·cm−3.[2]
The IrF6 molecule itself (the form important for the liquid or gas phase) has octahedral molecular geometry, which has point group (Oh). The Ir–F bond length is 1.833 Å.[2]
Calculations suggest that fluorine might react with iridium hexafluoride at 39 GPa to form IrF8.[3]
References
- ^ a b c d CRC Handbook of Chemistry and Physics, 90th Edition, CRC Press, Boca Raton, Florida, 2009, ISBN 978-1-4200-9084-0, Section 4, Physical Constants of Inorganic Compounds, p. 4-85.
- ^ a b c T. Drews, J. Supeł, A. Hagenbach, K. Seppelt: "Solid State Molecular Structures of Transition Metal Hexafluorides", in: Inorganic Chemistry, 2006, 45 (9), S. 3782–3788; doi:10.1021/ic052029f; PMID 16634614.
- ^ Lin, Jianyan; Zhao, Ziyuan; Liu, Chunyu; Zhang, Jing; Du, Xin; Yang, Guochun; Ma, Yanming (2019-03-13). "IrF8 Molecular Crystal under High Pressure". Journal of the American Chemical Society. 141 (13). American Chemical Society (ACS): 5409–5414. doi:10.1021/jacs.9b00069. ISSN 0002-7863. PMID 30864432. S2CID 76664353.
Further reading
- Gmelins Handbuch der anorganischen Chemie, System Nr. 67, Iridium, Supplement Volume 2, pp. 99–102.
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