Bipyridyl second ligand dependent structural and magnetic properties of Cu(II) complexes with pyridine-2,6-dicarboxylate and water molecule as first ligand

Three new mononuclear complexes [Cu(pdc)L(H2O)] center dot xH(2)O (L = 2,4'-bpy, x = 4 (1); L = 5-ph-2,4'-bpy, x = 2 (2); L = 5-Cl-2,4'-bpy, x = 0 (3)) were prepared in the reaction of pyridine-2,6-dicarboxylic acid (H(2)pdc) with divalent copper ions under hydrothermal conditions in the presence of three second bipyridyl ligands, respectively. The divalent copper ions adopted N2O3 five coordination with pyridine-2,6-dicarboxylate (pdc(2-)), one water, and 2,4'-bipyridine (2,4'-bpy) or its derivative such as 5-phenyl-2,4'-bipyridine (5-ph-2,4'-bpy) or 5-chloro-2,4'-bipyridine (5-Cl-2,4'-bpy), where lattice water clusters possessing different configuration are formed for 1 and 2. In 1, (H2O)(8) molecules adopting a chairlike conformation stack along the a-axis to form a water tape. Hexameric water cluster self-assembles forming a highly ordered comblike infinite chain in 2. Unlike 1 and 2, no lattice water molecule was found in 3, except one coordination water molecule as found in 1 and 2. It was found that the anti ferro magnetic interactions between the Cu-II ions can be tuned by the number of lattice water molecules for these three complexes.