Platinum(VI) fluoride

Platinum hexafluoride is the chemical compound with the formula Pt F₆. It is a dark-red volatile solid that forms a dark red gas. The compound is a unique example of platinum in the 6+ oxidation state. With only four d-electrons, it is paramagnetic with a triplet ground state.

PtF₆ is a strong oxidant and a strong fluorinating agent that is best known for its reaction with xenon to form "XePtF₆," known as xenon hexafluoroplatinate. The discovery of this reaction in 1962 proved that noble gases form chemical compounds. Previous to the experiment with xenon, PtF₆ had been shown to react with oxygen to form (O₂)⁺(PtF₆)⁻, dioxygen hexafluoroplatinate.

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Synthesis

PtF₆ was first prepared by reaction of fluorine with platinum metal^[1] This route remains the method of choice.^[2]

Pt + 3 F₂ → PtF₆

PtF₆ can also be prepared by disproportionates of PtF₅. The required PtF₅ can be obtained by fluorinating PtCl₂

PtCl₂ + 2.5 F₂ → PtF₅ + Cl₂

2 PtF₅ → PtF₆ + PtF₄

Other hexafluoride compounds

The neutral hexafluorides of other elements are also volatile. These include osmium, iridium, rhodium, ruthenium, rhenium, tungsten, technetium, and uranium. All are aggressive oxidants. Uranium hexafluoride and tungsten hexafluoride are used in the nuclear and microelectronics industries respectively. In the main group elements, sulfur, xenon, selenium, and tellurium form isolable hexafluorides. Sulfur hexafluoride is so extremely stable, perhaps due to steric effects, that it is used as an inert fluid in transformers. The analogues selenium hexafluoride and tellurium hexafluoride are, however, strongly reactive.

Like the hexafluorides of Mo, Tc, Ru, Rh, W, Re, Os, and Ir, PtF6 is octahedral in both the solid state and in the gaseous state. The Pt-F bond lengths are 1.85 .^[2]

References

1. ^ Weinstock, B.; Claassen, H. H.; Malm, J. G. “Platinum Hexafluoride” Journal of the American Chemical Society 1957, volume 79, pp 5832 - 5832. doi:10.1021/ja01578a073
2. ^ ^{a b} Drews, T.; Supel, J.; Hagenbach, A.; Seppelt, K. “Solid State Molecular Structures of Transition Metal Hexafluorides” Inorganic Chemistry 2006, volume 45, pp 3782-3788.doi:10.1021/ic052029f

General reading

• Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.