Crystal structure of bis-(propane-1,3-diaminium) hexa-fluorido-aluminate di-aqua-tetra-fluorido-aluminate tetra-hydrate.

The title compound, (C3H12N2)2[AlF6][AlF4(H2O)2]·4H2O, was obtained by a solvothermal method in ethanol as solvent and with aluminium hydroxide, HF and 1,3-di-amino-propane as educts. The asymmetric unit contains a quarter each of two crystallographically independent propane-1,3-di-ammonium dicat-ions, AlF6 and AlF4(H2O)2 anions and four water mol-ecules. The cations, anions and three of the independent water mol-ecules are situated on special positions mm, while the fourth water mol-ecule is disordered about a mirror plane. In the crystal, inter-molecular N-H⋯F and O-H⋯F hydrogen bonds link the cations and anions into a three-dimensional framework with the voids filled by water mol-ecules, which generate O-H⋯O hydrogen bonds and further consolidate the packing.