The title compound, {[Ba7(C3H5O2)14]·0.946C3H6O2·4H2O} n , is represented by a metal-organic framework structure that is held together by Ba-O-Ba bonds, as well as by O-H⋯O hydrogen bonds of moderate strength. The structure comprises of four independent Ba2+ cations (one of which is situated on a twofold rotation axis), seven independent propionate and two independent water mol-ecules. The bond-valence sums of all the cations indicate a slight overbonding. There is also an occupationally, as well as a positionally disordered propionic acid mol-ecule present in the structure. Its occupation is slightly lower than the full occupation while the disordered mol-ecules occupy two positions related by a rotation about a twofold rotation axis. In addition, the methyl group in the symmetry-independent propionic acid mol-ecule is also disordered, and occupies two positions. Each propionic acid mol-ecule coordinates to just one cation from a pair of symmetry-equivalent Ba2+ sites and is simultaneously bonded by an O-H⋯Opropionate hydrogen bond. This means that on a microscopic scale, the coordination number of the corresponding Ba2+ site is either 9 or 10. The methyl as well as hy-droxy hydrogen atoms of the disordered propionic acid mol-ecule were not determined.
Keywords: crystal structure; hydrogen bonding; metal–organic compounds; occupational disorder; positional disorder.
© Samolová and Fábry 2020.