Poly[[aqua(μ-2,2-dimethylmalonato)barium(II)]2,2-dimethylmalonic acid solvate]

In the title complex, {[Ba(C5H6O4)(H2O)]center dot C5H8O4}(n), the neutral dimethylmalonic acid molecules and the dianionic (dimethylmalonato) barium metal-organic framework are linked by cocrystallization. The Ba atom, in a distorted monocapped square-antiprismatic geometry, is nine-coordinated by seven O atoms of four different dimethylmalonate groups and by two water molecules. This arrangement generates a two-dimensional layer parallel to the bc plane. Two such layers sandwich another layer composed of neutral dimethylmalonic acid molecules that are involved in intermolecular hydrogen bonds within this layer and to neighboring layers. This complex is different from the dimethylmalonate-Ba complex reported previously. The title compound displays a novel structure type and represents a new member of the substituted malonate series of alkaline earth complexes.