Poly[[tetra­deca­kis­(μ-propionato)hepta­barium] propionic acid monosolvate tetra­hydrate]

The title compound, {[Ba(7)(C(3)H(5)O(2))(14)]·0.946C(3)H(6)O(2)·4H(2)O}(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 Ba(2+) cations (one of which is situated on a twofold rotation axis), seven independent propionate and two independent water mol­ecules. 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 mol­ecule present in the structure. Its occupation is slightly lower than the full occupation while the disordered mol­ecules occupy two positions related by a rotation about a twofold rotation axis. In addition, the methyl group in the symmetry-independent propionic acid mol­ecule is also disordered, and occupies two positions. Each propionic acid mol­ecule coordinates to just one cation from a pair of symmetry-equivalent Ba(2+) sites and is simultaneously bonded by an O—H⋯O(propionate) hydrogen bond. This means that on a microscopic scale, the coordination number of the corresponding Ba(2+) site is either 9 or 10. The methyl as well as hy­droxy hydrogen atoms of the disordered propionic acid mol­ecule were not determined.