Compounds of argon, krypton and radon

The chemistry of argon is still in its infancy. Photolysis of HF in a solid argon matrix results in the formation of HArF, which has been identified by comparing the IR 

KtF2 also acts as a very powerful oxidizing agent. An unusual example of the interaction of KrFa with a p-block element without oxidation of the latter or transfer of F, is observed in the reaction of KrFa with [BrOF2][AsF6] (eq. 18.27). The product is stable at low temperature for several days and the solid state structure (Fig. 18.10) confirms adduct formation between KrF2 and the bromine(V) atom. 

In the examples above, KrF2 reacts with Lewis acids that are strong enough F acceptors to abstract F. In reaction 

Radon is oxidized by halogen fluorides (e.g. CIF, CIF3) to the non-volatile Rnp2. The latter is reduced by H2 at 770 K, and is hydrolysed by water in an analogous manner to Xep2 (eq. 18.3). As we mentimied in Section 18.1, httle chemistiy of radon has been explored. 

Christe (2001) Angew. Chem. Int. Ed., vol. 40, p. 1419 - An overview of recent developments A renaissance in noble gas chemistry . 

Few compounds are known that contain Kr bonded to elements other than F. The reactions between KrF2, RC=N (e.g. R = H, CF3) and ASF5 in liquid HF or BrFs yield [(RCN)KrF] [AsF6] with Kr—N bond formation, and Kr—O bond formation has been observed in the reaction of KrF2 and B(OTeF5)3 to give Kr(OTeF5)2. 

Frenking and D. Creme (1990) Structure and Bonding, vol. 73, p. 17 - A review The chemistry of the noble gas elements helium, neon and argon . 

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Occurrence and extraction Applications Physical properties Compounds of xenon Compounds of argon, krypton and radon... 

Radon forms a series of clathrate compounds (inclusion compounds) similar to those of argon, krypton, and xenon. These can be prepared by mixing trace amounts of radon with macro amounts of host substances and allowing the mixtures to crystallize. No chemical bonds are formed the radon is merely trapped in the lattice of surrounding atoms it therefore escapes when the host crystal melts or dissolves. Compounds prepared in this manner include radon hydrate, Rn 6H20 (Nikitin, 1936) radon-phenol clathrate, Rn 3C H 0H (Nikitin and Kovalskaya, 1952) radon-p-chlorophenol clathrate, Rn 3p-ClC H 0H (Nikitin and Ioffe, 1952) and radon-p-cresol clathrate, Rn bp-CH C H OH (Trofimov and Kazankin, 1966). Radon has also been reported to co-crystallize with sulfur dioxide, carbon dioxide, hydrogen chloride, and hydrogen sulfide (Nikitin, 1939). 

L. V. Gurvich, I. V. Veyts, and C. B. Alcock, Thermodynamic Properties of Individual Substances, Vol. 1 Elements Oxygen, Hydrogen (Deuterium, Tritium), Fluorine, Chlorine, Bromine, Iodine, Helium, Neon, Argon, Krypton, Xenon, Radon, Sulfur, Nitrogen, Phosphorus, and Their Compounds, Pt. 1 Methods and Computation, Hemisphere, New York, 1989. 

Stable compounds of krypton and radon have also been synthesized. Helium, neon, and argon form no known stable compounds, but they have been observed to form compounds for short periods of time. 

The product is a volatile, colorless solid (Figure 22.52). Since then, a number of noble-gas compounds have been prepared that typically involve bonds to the highly electronegative elements fluorine and oxygen. Most of these are compounds of xenon (see Table 22.12), but a few are compounds of krypton and radon. Recently, an argon compound, HArF, was synthesized as well as compounds of CUO bonded to Ne, Ar, Kr, and Xe. All of these recent compounds were synthesized at very low temperatures. 

The elements helium, neon, argon, krypton, xenon, and radon—known as the noble gases—almost always have monatomic molecules. Their atoms are not combined with atoms of other elements or with other atoms like themselves. Prior to 1962, no compounds of these elements were known. (Since 1962, some compounds of krypton, xenon, and radon have been prepared.) Why are these elements so stable, while the elements with atomic numbers 1 less or 1 more are so reactive The answer lies in the electronic structures of their atoms. The electrons in atoms are arranged in shells, as described in Sec. 3.6. (A more detailed account of electronic structure will be presented in Chap. 17.)... 

Compounds of the three heavier noble gases, krypton (Kr), xenon PCe), and radon (Rn), have been made, but the formation of stable compounds of the hghter noble gases, helium (He), neon (Ne), and argon (Ar), has been more difficult. Recently a positive ion has been formed by combining hydrogen with hehum (HeH ). 

RARE GAS. Any of the six gases composing the extreme right-hand group of the periodic table, namely helium, neon, argon, krypton, xenon, and radon. They are preferably called noble gases or (less accurately) inert gases. The first three have a valence of 0 and are truly inert, but the others can form compounds to a limited extent,... 

The Group 18 elements in the periodic table are currently called the noble gases. In the past, however, they were referred to as the inert gases. They were believed to be totally unreactive. Scientists have found that this is not true. Some of them can be made to react with reactive elements, such as fluorine, under the proper conditions. In 1962, the synthesis of the first compound that contained a noble gas was reported. Since then, a number of noble gas compounds have been prepared, mostly from xenon. A few compounds of krypton, radon, and argon have also been prepared. 

Group 0, the noble gases The elements of this group, helium, neon, argon, krypton, xenon, and radon, are completely unreactive chemically they do not form any chemical compounds. A discussion of the noble gases is given in the following sections of this chapter. 

The noble gases are sometimes called the inert gases. This name comes from the fact that these elements do not react very readily. In fact, compounds exist for only four noble gases—argon, krypton, radon, and xenon. Chemists have yet to prepare compounds of helium or neon. 

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