Correlations between ²⁷Al magic-angle spinning nuclear magnetic resonance spectra and the coordination geometry of framework aluminates

A range of aluminate sodalites of general formula M(AlO) · X, where M and X are a divalent cation and anion, respectively, has been synthesised. The structures of these materials, which contain a single aluminum environment, have been refined from powder X-ray or neutron diffraction data and the compounds further characterised using Al magic-angle spinning nuclear magnetic resonance (MAS NMR). Correlations between (i) the AlOAl bond angles and the Al chemical shift and (ii) the quadrupolar coupling constant and the distorted AlO tetrahedral geometry have been determined.