Dioxygenyl hexafluoroplatinate is a compound with formula O2PtF6. It is a hexafluoroplatinate of the unusual dioxygenyl cation, O2+, and is the first known compound containing this cation. It can be produced by the reaction of dioxygen with platinum hexafluoride:
Contents
O2 + PtF6 → O2PtF6The fact that PtF
6 is a strong enough oxidiser to oxidise O
2, whose first ionization potential is 12.2 eV, led Neil Bartlett to surmise that it might also be able to oxidise xenon, whose first ionization potential is 12.13 eV. This led to the discovery of xenon hexafluoroplatinate, which proved that the noble gases, previously thought to be inert, are able to form chemical compounds.
Preparation
Dioxygenyl hexafluoroplatinate can be synthesized from the elements by the action of a mixture of oxygen and fluorine gas on platinum sponge at 450°C.
It can also be prepared by the reaction of oxygen difluoride OF
2 with platinum sponge. At 350°C, platinum tetrafluoride is produced; above 400°C, dioxygenyl hexafluoroplatinate is formed.
It can be synthesized at room temperature by the reaction of oxygen gas with PtF
6.
Structure
Dioxygenyl hexafluoroplatinate(V) has a rhombohedral crystal structure at low temperatures, and a cubic structure at high temperatures, isomorphous to potassium hexafluoroplatinate(V), KPtF
6. Its ionic lattice is indicated by its insolubility in carbon tetrafluoride. In its cubic form, the [PtF
6]−
octahedra are slightly compressed along the three-fold rotational axis, along which the long axis of the [O
2]+
cations also lies. Each [O
2]+
cation is surrounded by 12 fluorine atoms, 6 of which surround it in a puckered six-membered ring, and of the remaining 3 each belong to the two [PtF
6]−
octahedra lying along the long axis of the cation.
Reactions
Dioxygenyl hexafluoroplatinate(V) is a convenient route to prepare other platinum(V) compounds, such as potassium hexafluoroplatinate(V) via reaction with potassium fluoride in iodine pentafluoride (IF
5) solution:
2PtF
6 + KF → KPtF
6