Anionic Clathrate

Assuming that the 2c-2e covalent-bond description is sufihcient for the interpretation of chemical bonding within the framework of anionic clathrates, the... 

Chemistry and Physics of Inverse (Cationic) Clathrates and Tin Anionic Clathrates... 

Distribution of atoms of different nature over the framework positions deserves more discussion. It is noticed that the 16 site of the space group Pm3n is always occupied by atoms of the most electronegative elements— phosphorus or arsenic, whereas the most electropositive elements prefer the 24 site. The latter position is always occupied by various metal atoms, including transition metals copper and zinc and p-metals, such as tin and indium. Another important feature is that vacancies form at the 6c or 24k sites but never at the 16 sites. This pattern is remarkably different from that observed for anionic clathrates. In them, electropositive substituents, including group 13 and some transition metals, either exclusively sit on the 6c site or also occupy the 24 site but always avoid the... 

Tin anionic clathrates exhibit low values of thermal conductivity in the range of 0.6-2 Wm K . This is lower than the values for anionic Si- and Ge-containing clathrates with similar framework compositions and the same cations. This indicates that clathrate framework atoms play an important role in the scattering of heat-carrying phonons. Thus, the frameworks with heavier Sn atoms scatter phonons more effectively. 

The strong affinity of ionic liquids for aromatics has been attributed to the formation of liquid clathrates (90-92). Liquid clathrates (93) are semi-ordered liquids containing complex salt hosts. They are formed by associative interactions between aromatic molecules and salt ions, which separate cation-anion-packing interactions to a sufficient degree that localized cage structures are formed. Although the aromatic compounds are highly soluble in the ionic liquid phase, the... 

The typical liquid clathrate is characterized by (a) a low viscosity relative to that of a neat ionic liquid, (b) immiscibility with excess aromatic solvents, and (c) non-stoichiometric compositions. The formation of air- and water-stable liquid clath-rates has been reported for the compositions consisting of aromatic hydrocarbons (e.g., benzene, toluene, and xylenes) and common salts of [AMIM] cation with the anions PF, [Tf2N] , BFJ, and Cl 91). 

Clathrate hydrates can be formed not only with neutral organic molecules but also with alkylammonium salts with small anionic counteranions [37] and with guests involving polymeric anions [38]. 

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