μ-4,4'-Bipyridine-κ2N:N'-bis[triaqua(4,4'-bipyridine-κN)cadmium(II)] bis(3-aminobenzoate) bis(perchlorate) dihydrate: a novel supramolecular system constructed by π-π and hydrogen-bonding interactions.

The title dicadmium compound, [Cd(2)(C(10)H(8)N(2))(5)(H(2)O)(6)](C(7)H(6)NO(2))(2)(ClO(4))(2)·2H(2)O, is located around an inversion centre. Each Cd(II) centre is coordinated by three N atoms from three different 4,4'-bipyridine ligands and three O atoms from three coordinating water molecules in a distorted octahedral coordination environment. In the dicadmium cation unit, one 4,4'-bipyridine (4,4'-bipy) molecule acts as a bidentate bridging ligand between two Cd metal ions, while the other four 4,4'-bipy molecules act only as monodentate terminal ligands, resulting in a rare `H-type' [Cd(2)(C(10)H(8)N(2))(5)(H(2)O)(6)] host unit. These host units are connected to each other via π-π stacking interactions, giving rise to a three-dimensional supramolecular grid network with large cavities. The 3-aminobenzoate anions, perchlorate anions and water molecules are encapsulated in the cavities by numerous hydrogen-bonding interactions. To the best of our knowledge, this is the first example of a coordination compound based on both 4,4'-bipyridine ligands together with discrete 3-aminobenzoate anions.