Xenon hexafluoroplatinate
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| Xenon hexafluoroplatinate | |
|---|---|
| Systematic name | Xenon hexafluoroplatinate |
| Other names | note: this existence of this compound is disputed |
| Molecular formula | F6PtXe |
| Molar mass | 440.3604 g/mol |
| Density | x.xxx g/cm3 |
| Solubility (water) | reacts with water |
| CAS number | [xx-xx-xx] |
| Disclaimer and references | |
Xenon hexafluoroplatinate is the description of the product obtained when the chemical reactivity of noble gas was first demonstrated. The material was synthesized at the University of British Columbia by Neil Bartlett in 1962, giving evidence that noble gases can form chemical compounds. He formulated the product as "Xe+[PtF6]−", although recent work suggests that Bartlett's product was probably impure and did not in fact contain this specific salt.
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[edit] Preparation
"Xenon hexafluoroplatinate" is prepared by mixing Xe and platinum hexafluoride (PtF6) as gaseous solutions in SF6. The reactants were combined at 77K and slowly warmed, presumably to allow for a controlled reaction.
[edit] What is "xenon hexafluoroplatinate"?
The structure of xenon hexafluoroplatinate is likely not Xe+[PtF6]−. The main problem with this formulation is "Xe+", which would be a radical and would dimerize or abstract an F atom to give XeF+. Thus, Bartlett discovered that Xe undergoes chemical reactions, but the nature of his initial mustard yellow product is complex.[1] Further work indicates that Bartlett's product probably contained [XeF+][PtF6]−, [XeF+][Pt2F11]−, [Xe2F3+][PtF6−].[2] The title compound is ionic, consisting of an octahedral anionic fluoride complex of platinum and various xenon cations.[3]
It has been proposed that the platinum fluoride structure forms a negatively charged polymeric network with xenon or xenon fluoride cations held in its meshes. A preparation of XePtF6 in HF solution results in a solid which has been characterized as a [PtF5-]n polymeric network associated with XeF+. This result is evidence for such a polymeric structure of xenon hexafluoroplatinate.[1]
[edit] History
Linus Pauling suggested that some noble gas compounds could be made, although they would violate the octet rule.[4] In 1962, Neil Bartlett discovered that a sample of platinum hexafluoride gas kept overnight became a red solid.[5] The red solid turned out to be dioxygenyl hexafluoroplatinate, O2[PtF6], in which an electron has been removed from the oxygen molecule by the platinum hexafluoride molecule. Bartlett later compared the ionization energies required for removal of the first electron from O2 molecule and from Xe and found that the energies required were similar. Then he asked his colleagues to give him some xenon "so that he could try out some reactions", and he established that xenon indeed reacted with PtF6. Although, as discussed above, the product was probably highly impure, Bartlett's discovery was the first proof that compounds could be prepared from a noble gas. The overall history illustrates important characteristics of research leading to new chemical methods: Initial reactions often lead to impure products. Since Bartlett's time, many well-defined compounds of xenon have been reported including XeF2, XeF4, and XeF6.
Noble gases are elements which do not easily participate in chemical bonding because their valence electron shells are filled. For the heavier noble gases such as xenon, the outer electrons are more shielded from electronic interactions with the nucleus. These less tightly bound outer electrons have been found to participate in chemical bonding. [6]
[edit] References
- ^ a b Graham, L.; Graudejus, O., Jha N.K., and Bartlett, N. (2000). "Concerning the nature of XePtF6". Coordination Chemistry Reviews 197: 321–334. DOI:10.1016/S0010-8545(99)00190-3.
- ^ Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
- ^ The American Chemical Society "molecule of the week" (2006). "Xenon Hexafluoroplatinate"
- ^ Chemical Heritage foundation (2006). "William Ramsay".
- ^ Bartlett, N. (1962). Xenon hexafluoroplatinate Xe+[PtF6]− Proceedings of the Chemical Society of London 218-.
- ^ Gerber, R.B.(2004). Annual Review of Physical Chemistry 55, 55-78.
