Exploring the viability of noble gas endohedral siladodecahedranes and its perhalogenated derivatives

Herein, a study of the thermodynamic and kinetic stability of compounds containing noble gases (Ngs) encapsulated within the cage-like structure of recently synthesized siladodecahedrane (Si₂₀H₂₀) and its halogenated derivatives is reported. All systems present Gibbs energy values close to zero at 298K implying they could be thermodynamically stable structures at low or cryogenic temperatures. Furthermore, the results also show that these systems are kinetically stable, having a very high energy barrier for Ng release, and their structures persist without major modifications throughout molecular dynamics simulations. Chemical interactions between Ngs and Si₂₀X₂₀ systems (X = H, F, Cl, Br and I) have been analyzed, results indicate that interactions are mainly non-covalent, showing a slight charge donation from the noble gas to the cage. Finally, it was found that for lighter Ngs, the repulsive interactions with the cage are lower than for the heavier ones, which accounts for their thermodynamic stability at low temperatures.