Xenon compounds fluorides

The starting point for the synthesis of xenon compounds is the preparation of xenon difluoride, XeF2, and xenon tetrafluoride, XeF4, by heating a mixture of the elements to 400°C at 6 atm. At higher pressures, fluorination proceeds as far as xenon hexafluoride, XeFfi. All three fluorides are crystalline solids (Fig. 15.27). In the gas phase, all are molecular compounds. Solid xenon hexafluoride, however, is ionic, with a complex structure consisting of XeF< + cations bridged by F anions. 

Xenon(II) fluoride trifluoroacetate [25710-89-8] F3CCO.OXeF Jha. N. K RICRev., 1971, 4, 157 It explodes on thermal or mechanical shock. See other XENON compounds C2F402Xe... 

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). 

Russian scientists (Avrorin et al., 1981, 1985) have reported that reactions of complex mixtures of radon, xenon, metal fluorides, bromine pentafluoride, and fluorine yield a higher fluoride of radon which hydrolyzes to form RnO. However, efforts to confirm these findings have been unsuccessful. In similar experiments which have been carried out at Argonne National Laboratory (Stein, 1984), it has been found that radon in the hydrolysate is merely trapped in undissolved solids centrifugation removes the radon from the liquid phase completely. This is in marked contrast to the behavior of a solution of XeO, which can be filtered or centrifuged without loss of the xenon compound. Hence there is no reliable evidence at present for the existence of a higher oxidation state of radon or for radon compounds or ions in aqueous solutions. Earlier reports of the preparation of oxidized radon species in aqueous solutions (Haseltine and Moser, 1967 Haseltine, 1967) have also been shown to be erroneous (Flohr and Appelman, 1968 Gusev and Kirin, 1971). 

In the 1960s, scientists first produced compounds of xenon and some other noble gases at the Argonne National Laboratory located near Chicago. Xenon and krypton are the only noble gases that readily form compounds with oxygen and fluorine. For instance, when xenon combines with fluorine, it can form a series of compounds, such as xenon difluoride PCeF ), xenon tetra-fluoride (XeF ), and xenon hexafluoride pCeF ). These and other compounds of xenon are formed within metal containers at high temperatures and pressures. They are not stable. 

Various fluorine compounds, such as xenon(II) fluoride, act under certain conditions (irradiation, gas-phase reaction) as radical fluorinating agents. Electrochemical fluorinations (see Section 7.) carried out in hydrogen fluoride containing systems (ref 7, pp73-76) are further examples of radical-type reactions. 

Tris(dimethylamino)sulfonium difluo-rotrimethylsilicate, 336 Xenon(II) fluoride, 345 Alkyl bromides Potassium permanganate, 258 Sodium bromide, 46 Tetraethylammonium bromide, 46 Alkyl iodides Aluminum iodide, 17 Potassium permanganate, 258 Sodium iodide, 46 Tetraethylammonium iodide, 46 Alkynes (see also Acetylenic carbonyl compounds, Diynes, Enynes, Propar-gyl alcohols)... 

Not only were the fluorides the first compounds of xenon to be prepared, but also they serve as starting materials for the synthesis of most other xenon compounds. Xenon difluoride can be prepared by the reaction of excess xenon with fluorine aided by heat or electromagnetic radiation ... 

Xenon compounds Xenon forms some binary fluorides and oxides, as well as fluoride complexes and oxoanions. All are very reactive compounds. 

With the exception of XeF, which is obtained as an unstable free radical (2-4), there is no evidence for the occurrence of xenon compounds in odd-numbered oxidation states. The only species that can be synthesized directly from the elements are the three fluorides XeF2, XeF4, and XeF6. Early reports of the preparation of XeFs have not been substantiated. 

This formation of XeFf and XeFf- salts from XeF6 resembles the behavior of UF6. The Rb and Cs octafluoroxenates are the most stable xenon compounds yet made and decompose only above 400° they hydrolyze in the atmosphere to give xenon-containing oxidizing products. The sodium fluoride adduct of XeF6 decomposes below 100° and can be used to purify XeF6. 

Because the noble gases have filled 5 and p valence orbitals, they were not expected to be chemically reactive. In fact, for many years these elements were called inert gases because of this supposed inability to form any compounds. However, in the early 1960s several compounds of krypton, xenon, and radon were synthesized. For example, a team at the Argonne National Laboratory produced the stable colorless compound xenon tetra-fluoride (Xep4). Predict its structure and whether it has a dipole moment. 

One of the few xenon compounds that form is cesium xenon heptafluoride (CsXeFy). How many moles of CsXeFy can be produced from the reaction of 12.5 mol of cesium fluoride with 10.0 mol of xenon hexafluoride ... 

This suggestion of Pauling s went unheeded at first, but in 1962, xenon fluoride was formed by reacting the inert gas xenon with fluorine. In short order a number of xenon compounds with fluorine and with oxygen were formed, as well as one or two of radon and of krypton. 

Argon (Ar) gas, for example, is over 30 times more abundant than carbon dioxide and, therefore, not rare. And xenon is not inert it s first compounds were created in 1962. When xenon (Xe) forms binary fluorides and oxides as well as fluoride complexes and oxoanions, the stability of these compounds is very low. It s reactivity is related to increasing atomic size as you go down the table, which leads to a decrease in the first ionization potentials. Xenon tetraflouride (XeF,) is made by mixing one part xenon gas to three parts fluorine gas in a container at 400 °C. Compounds have been confirmed for argon (HArF), krypton (KrF2), xenon (numerous fluorides, oxyfluorides, and oxides), and radon (RnF2). It s believed that compounds exist with helium and neon as well, though none have been experimentally proven to date. 

---