Hydrothermal syntheses, structures and magnetic properties of two transition metal coordination polymers with a square grid framework

Two coordination polymers, [M(NDA)(4,4'-bpy)(H2O)(2)] . nH(2)O (M = Co, n = 1 (1); M = Ni, n = 0.5 (2), NDA = 1,4-naphthalenedicarboxylate. 4,4'-bpy = 4,4'-bipyridine) have been synthesized by the hydrothermal reaction of MCl2 . 6H(2)O, NDA and 4,4'-bpy. Single-crystal X-ray diffraction analysis shows that they are isostructural and represent the first examples of a square grid metal-organic framework constructed by a transition metal, dicarboxylate and 4,4'-bpy with each edge formed by one ligand. The layers are assembled together through hydrogen bonding, resulting in a 3-D supramolecular architecture. Magnetic susceptibility studies reveal that there is a weak antiferromagnetic exchange interaction between the Co(II) ions in the 2-D square grid network of 1, and a weak ferromagnetic exchange interaction between the Ni(II) ions in 2. (C) 2004 Elsevier Ltd. All rights reserved.