Synthesis and Characterization of a Novel Binuclear Cobalt(II) Complex with Discrete Water Clusters (H 2 O) 8

A new octameric water cluster was observed in the complex Co 2 (dptc)(bipy) 2 (H 2 O) 6 · 4H 2 O ( 1 ) (H 4 dptc = diphenyl‐3,3′,4,4′‐tetracarboxylic acid; bipy = 2,2′‐bipyridine), which was characterized by single‐crystal X‐ray diffraction, elemental analysis and IR spectroscopy. The centrosymmetric octamer consists of a water hexamer in the chair form and two water molecules and brings to light a novel mode of the cooperative association of water molecules. Those complex units are connected into a 2D infinite layer framework through hydrogen bonding. Consequently, the 2D layers are further aggregated by hydrogen bonding with octameric subunits and π ··· π stacking interactions to form a 3D supramolecular architecture.