2-Dimensional sheet structures from linked metal fluoride tetrahedra

Abstract

Two 2-dimensional lithiumfluoroberyllate compounds, that possess identical anionic sheet topologies, have been synthesised from aqueous solutions under hydrothermal and ambient pressure conditions. The structures of [Li₂Be₂F₈][C₂N₂H₁₀], 1, and [Li₂Be₂F₈][CH₃NH₃]₂·[H₂O]₂, 2, consist of inorganic layers, constructed from linked [MF₄] (M = Li, Be) tetrahedra with organic templating cations incorporated between the sheets. For the ethylenediammonium cation, 1, the structure is a C-centred monoclinic cell, (space group C2/c), whereas the methylamine hydrate, 2, crystallises in P2₁/c, The interlayer regions possess corrugated topologies within which the organic moieties lie with the amine groups directed into the larger pockets. Hydrogen bonding exists between ions situated on the protonated amine groups on the templating species and electronegative fluoride ions.