Iridium hexafluoride, also iridium(VI) fluoride, (IrF₆) is a compound of

iridium Iridium is a chemical element with the symbol Ir and atomic number 77. A very hard, brittle, silvery-white transition metal of the platinum group, it is considered the second-densest naturally occurring metal (after osmium) with a density of ...

and

fluorine Fluorine is a chemical element with the symbol F and atomic number 9. It is the lightest halogen and exists at standard conditions as a highly toxic, pale yellow diatomic gas. As the most electronegative reactive element, it is extremely reacti ...

and one of the seventeen known binary

hexafluoride A hexafluoride is a chemical compound with the general formula QXnF6, QXnF6m−, or QXnF6m+. Many molecules fit this formula. An important hexafluoride is hexafluorosilicic acid (H2SiF6), which is a byproduct of the mining of phosphate rock. In ...

s. It is one of only a few compounds with iridium in the

oxidation state In chemistry, the oxidation state, or oxidation number, is the hypothetical charge of an atom if all of its bonds to different atoms were fully ionic. It describes the degree of oxidation (loss of electrons) of an atom in a chemical compound. C ...

+6.

Synthesis

Iridium hexafluoride is made by a direct reaction of iridium metal in an excess of elemental

gas at 300 °C. However, it is thermally unstable and must be frozen out of the gaseous reaction mixture to avoid dissociation. : + 3 →

Description

Iridium hexafluoride is a yellow crystalline solid that melts at 44 °C and boils at 53.6 °C. The solid structure measured at −140 °C is

orthorhombic In crystallography, the orthorhombic crystal system is one of the 7 crystal systems. Orthorhombic lattices result from stretching a cubic lattice along two of its orthogonal pairs by two different factors, resulting in a rectangular prism with a r ...

space group ''Pnma''.

Lattice parameters Lattice may refer to: Arts and design * Latticework, an ornamental criss-crossed framework, an arrangement of crossing laths or other thin strips of material * Lattice (music), an organized grid model of pitch ratios * Lattice (pastry), an orna ...

are ''a'' = 9.411 Å, ''b'' = 8.547 Å, and ''c'' = 4.952 Å. There are four

formula unit In chemistry, a formula unit is the empirical formula of any ionic or covalent network solid compound used as an independent entity for stoichiometric calculations. It is the lowest whole number ratio of ions represented in an ionic compound. Exa ...

s (in this case, discrete molecules) per

unit cell In geometry, biology, mineralogy and solid state physics, a unit cell is a repeating unit formed by the vectors spanning the points of a lattice. Despite its suggestive name, the unit cell (unlike a unit vector, for example) does not necessaril ...

, giving a density of 5.11 g·cm⁻³. The IrF₆ molecule itself (the form important for the liquid or gas phase) has

octahedral molecular geometry In chemistry, octahedral molecular geometry, also called square bipyramidal, describes the shape of compounds with six atoms or groups of atoms or ligands symmetrically arranged around a central atom, defining the vertices of an octahedron. The oc ...

, which has point group ('' O_h''). The Ir–F

bond length In molecular geometry, bond length or bond distance is defined as the average distance between nuclei of two bonded atoms in a molecule. It is a transferable property of a bond between atoms of fixed types, relatively independent of the rest of ...

is 1.833 Å. It reacts with

at 39 GPa to form iridium octafluoride, IrF₈, according to calculation.

References

CRC Handbook of Chemistry and Physics The ''CRC Handbook of Chemistry and Physics'' is a comprehensive one-volume reference resource for science research. First published in 1914, it is currently () in its 103rd edition, published in 2022. It is sometimes nicknamed the "Rubber Bible ...

'', 90th Edition, CRC Press, Boca Raton, Florida, 2009, , Section 4, ''Physical Constants of Inorganic Compounds'', p. 4-85. T. Drews, J. Supeł, A. Hagenbach, K. Seppelt: "Solid State Molecular Structures of Transition Metal Hexafluorides", in: ''

Inorganic Chemistry Inorganic chemistry deals with synthesis and behavior of inorganic and organometallic compounds. This field covers chemical compounds that are not carbon-based, which are the subjects of organic chemistry. The distinction between the two disci ...

'', 2006, ''45 (9)'', S. 3782–3788; ; .

External links

Iridium hexafluoride at webelements.com
{{fluorine compounds Iridium compounds Hexafluorides Platinum group halides Octahedral compounds

Synthesis

Description

References

Further reading

External links