Clathrate compounds, 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). 

Trofimov, A. M. and Kazankin, Yu. N., Clathrate Compounds of p-Cresol with Noble Gases. II. Compound of p-Cresol with Krypton and Radon, Radiokhim. 8 720-723 (1966). 

Radon forms a series of clathrate compounds similar to those of krypton, xenon, and argon (e.g. Rn-6H20, RnGCeHsOH, Rn-3/ -ClC6H40H). 

An authoritative review on the chemistry of radon, which includes the formation of clathrate compounds, the simple and complex fluorides, ionic radon in solution, redox properties, and the various unsuccessful efforts to prepare an oxide and halides of radon other than the fluoride, was published by the most significant contributor to this field in 1983 (14). 

Prior to 1962 the rare gases were frequently called inert gases as no chemical compounds were known (there were a few clathrates and hydrates ), but the realization that the ionization potential of xenon was sufficiently low to be accessible to chemical reaction led to the preparation of several fluorides, oxides, oxyfluorides, and a hexafluoroplatinate of xenon. Several unstable krypton and radon compounds have been synthesized. 

Chemically, radon is a noble gas. As such, it is colorless, odorless, and almost chemically inert. Although radon is not chemically active, it is interesting to note that radon is not a totally inert gas either. Studies on radon chemistry have been reported in which compounds such as clathrates and complex fluorides have been formed. Compared with the other noble gases, radon is the heaviest and has the highest melting point, boiling point, critical temperature, and critical pressure. 

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