Anion effects on the crystal structures of Zn^II complexes containing 2,2′-bipyridine: Their photoluminescence and catalytic activities

Six new structures of Zn^II complexes containing 2,2′-bipyridine (2,2′-bpy) ligands have been determined. Halide anions were used as simple coordinating ligands to form a tetrahedral environment around the Zn^II ion. Nitrate and benzoate anions were used as chelating ligands to form an octahedral environment. For non-coordinating ClO4- and bridging SO42- anions, three 2,2′-bpy ligands chelate Zn^II to form an octahedral environment, and both ClO4- and SO42- anions occupy empty positions between the metal cations for charge balance. Polymeric structures of the Zn^II-2,2′-bpy complexes are produced by hydrogen bonding. [Zn(2,2′-bpy)(O₂CC ₆H₅)₂] catalyzed efficiently the transesterification reaction of esters with methanol under the neutral conditions, while the remaining compounds showed very slow conversions.