Supramolecular Interactions between Finite Tapes of Water Molecules and Hydrated Metal Ions To Produce Infinite Two-Dimensional Cationic Layers of Water Molecules

A supramolecular self-assembly of finite tapes of lattice water molecules with the coordinated water molecules of hydrated metal ions forms 2D cationic layers of water molecules in the coordination complex [Ni­(H2O)6]­[Ni­(Pydi)2(H2O)2]·4H2O (Pydi = 2,5-pyridinedicarboxylate). It reveals yet another unique mode of the cooperative association of water molecules. The anionic layers have a well-known 2D, nonporous metal–organic framework formed by the assistance from H-bonding of coordinating water molecules.