Radon difluoride

When radon is heated to 400°C with fluorine, a nonvolatile fluoride is formed (Fields et al., 1962, 1963). It has been deduced from the chemical behavior that the product is radon difluoride, RnF2. (Products of the tracer experiments have not been analyzed because of their small mass and intense radioactivity.)... 

Radon difluoride is quantitatively reduced to elemental radon by water in a reaction which is analogous to the reactions of krypton difluoride and xenon difluoride with water. Complex salts of radon also hydrolyze in this fashion. 

Stable solutions of radon difluoride can be prepared in nonaqueous solvents, such as halogen fluorides and hydrogen fluoride (Stein, 1969, 1970). Radon reacts spontaneously at 25°C or at lower temperatures with each of the halogen fluorides except IF3. It also reacts with mixed solvent-oxidant pairs, such as HF-BrF, HF-BrF, and IF -BrF, and solutions of NiF in HF. 

The difference in the ionization potentials of xenon and krypton (1170 versus 1351 kj/mol) indicates that krypton should be the less the reactive of the two. Some indication of the difference can be seen from the bond energies, which are 133 kj/mol for the Xe-F bond but only 50 kj/mol for the Kr-F bond. As a result, XeF2 is considerably more stable of the difluorides, and KrF2 is much more reactive. Krypton difluoride has been prepared from the elements, but only at low temperature using electric discharge. When irradiated with ultraviolet light, a mixture of liquid krypton and fluorine reacts to produce KF2. As expected, radon difluoride can be obtained, but because all isotopes of radon undergo rapid decay, there is not much interest in the compound. In this survey of noble gas chemistry, the... 

Radon, on the other hand, reacts readily with F2, yielding radon difluoride. The compound has not been fully characterized. It decomposes on vaporization and is believed to be an ionic compound. The strong radioactivity of all of radon s isotopes has discouraged detailed studies of its chemical properties the half-life of Rn, the longest lived of all radon isotopes, is only 3.82 days. 

Radon reacts spontaneously at room temperature with fluorine or chlorine trifluoride to form radon difluoride. Solid RnF2 glows with a yellow light but is not well-characterized due to the difficulties of working with the extremely radioactive radon. 

Other xenon halides include the dichloride, the tetrachloride, and the dibromide, but these are not particularly stable. Solutions of xenon trioxide, called xenic acid, are excellent oxidizing agents, as is the octahedral perxenate anion, XeOg. Krypton difluoride, a few nitrogen compounds of both xenon and krypton, and radon difluoride have also been prepared but are not well-characterized. 

Krypton difluoride cannot be synthesized by the standard high pressure-high temperature means used to prepare xenon fluorides because of the low thermal stabitity of KrF. There are three low temperature methods which have proven practical for the preparation of gram and greater amounts of KrF (141—143). Radon fluoride is most conveniently prepared by reaction of radon gas with a tiquid halogen fluoride (CIE, CIE, CIE, BrE, or lE ) at room temperature (144,145). 

No stable compounds of He, Ne or Ar are known. Radon apparently forms a difluoride and some... 

Since the discovery of the first noble gas compound, Xe PtF (Bartlett, 1962), a number of compounds of krypton, xenon, and radon have been prepared. Xenon has been shown to have a very rich chemistry, encompassing simple fluorides, XeF2> XeF, and XeF oxides, XeO and XeO oxyf luorides, XeOF2> XeOF, and Xe02 2 perxenates perchlorates fluorosulfates and many adducts with Lewis acids and bases (Bartlett and Sladky, 1973). Krypton compounds are less stable than xenon compounds, hence only about a dozen have been prepared KrF and derivatives of KrF2> such as KrF+SbF, KrF+VF, and KrF+Ta2F11. The chemistry of radon has been studied by radioactive tracer methods, since there are no stable isotopes of this element, and it has been deduced that radon also forms a difluoride and several complex salts. In this paper, some of the methods of preparation and properties of radon compounds are described. For further information concerning the chemistry, the reader is referred to a recent review (Stein, 1983). 

The chemistry of krypton is much more limited than that of xenon. Apparently only the difluoride forms directly from the elements. Attempts to make helium, neon, and argon fluorides have been unsuccessful. Radon should react even more readily than xenon, but its chemistry is complicated by the difficulty of working with a... 

Radon lies on the diagonal of the Periodic Table between the true metals and nonmetals and is classed as a metalloid. As the heaviest and most metallic of the naturally occurring noble gases, radon has the lowest ionization energy of the group (1030 kJ mol ) consequently, it is expected to be the most reactive. The chemistry of radon is, however, less extensive than the chemistries of krypton and xenon and is rendered considerably more difficult because no stable isotopes of this element exist. The inherent radiation hazard that accompanies the intense radioactivity of radon requires tracer level experimentation. Nevertheless, evidence has been obtained that radon forms a difluoride and several complex salts. 

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