Poly[μ-aqua-diaqua-μ4-malonato-μ3-malonato-barium(II)nickel(II)]

The title complex, [BaNi(C3H2O4)2(H2O)3](n), is polymeric, with two non-equivalent malonate dianions bridging one Ni atom and five different Ba atoms. The Ni atoms have a distorted octahedral (NiO6) environment, and are coordinated by four malonate O atoms in a planar arrangement and two water molecules in axial positions. The Ba atom may be described as a BaO9 polyhedron in a monocapped square-antiprismatic environment, which involves two water molecules and seven O atoms from different malonate ligands. The three-dimensional structure is further maintained and stabilized by hydrogen bonds.