SMARTER crystallography of the fluorinated inorganic-organic compound Zn ₃Al ₂F ₁₂·[HAmTAZ] ₆

We present in this paper the structure resolution of a fluorinated inorganic-organic compound - Zn ₃Al ₂F ₁₂· [HAmTAZ] ₆ - by SMARTER crystallography, i.e. by combining powder X-ray diffraction crystallography, NMR crystallography and chemical modelling of crystal (structure optimization and NMR parameter calculations). Such an approach is of particular interest for this class of fluorinated inorganic-organic compound materials since all the atoms have NMR accessible isotopes ( ¹H, ¹³C, ¹⁵N, ¹⁹F, ²⁷Al, ⁶⁷Zn). In Zn ₃Al ₂F ₁₂·[HAmTAZ] ₆, ²⁷Al and high-field ¹⁹F and ⁶⁷Zn NMR give access to the inorganic framework while ¹H, ¹³C and ¹⁵N NMR yield insights into the organic linkers. From these NMR experiments, parts of the integrant unit are determined and used as input data for the search of a structural model from the powder diffraction data. The optimization of the atomic positions and the calculations of NMR parameters ( ²⁷Al and ⁶⁷Zn quadrupolar parameters and ¹⁹F, ¹H, ¹³C and ¹⁵N isotropic chemical shifts) are then performed using a density functional theory (DFT) based code. The good agreement between experimental and DFT-calculated NMR parameters validates the proposed optimized structure. The example of Zn ₃Al ₂F ₁₂·[HAmTAZ] ₆ shows that structural models can be obtained in fluorinated hybrids by SMARTER crystallography on a polycrystalline powder with an accuracy similar to those obtained from single-crystal X-ray diffraction data.