Fluoride Ion Entrapment in Octasilsesquioxane Cages as Models for ion entrapment in Zeolites. Further examples, X-ray Crystal Structure studies, and investigations into how and why they may be formed

We have successfully prepared two further fluoride-encapsulated octasilsesquioxane cage compounds using our TBAF and scare water catalysed route as important molecular models for studying ion entrapment in siliceous zeolites. Analysis by X-ray crystal structure and solution 19F/29Si NMR spectroscopy reveal very similar environments for the encapsulated fluoride ion perfectly centred within each cage with evidence of weak silicon fluoride ion van der Waals interactions. By comparing our NMR and X-ray data with non-encapsulated cage analogues from the literature we observe the effect the fluoride ion has on the geometry of the cage and use the findings of related studies in the literature to suggest reasons why fluoride ion may be becoming entrapped in the silsesquioxane core