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, Cd₂(C₁₀H₈N₂)₅(H₂O)₆](C₇H₆NO₂)₂(ClO₄)₂·2H₂O, 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' Cd₂(C₁₀H₈N₂)₅(H₂O)₆] host unit. These host units are connected to each other viaπ–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.