One-dimensional copper-pyridinedicarboxylate polymer containing square-planar Cu(II) centers exhibiting antiferromagnetic coupling

The hydrothermal reaction of Cu(NO₃)₂·2.5H₂O with 2,5-pyridinedicarboxylic acid (2,5-PDCH₂) led to the formation of a one-dimensional coordination polymer with the empirical formula of Cu(2,5-PDC)(H₂O) (1). On the other hand, the hydrothermal reaction of Cu(NO₃)₂·2.5H₂O with 2,4-pyridinedicarboxylic acid (2,4-PDCH₂) gave a mononuclear Cu(II) compound Cu(2,4-PDC)₂ (2). The structures of both compounds have been determined by X-ray diffraction. In both compounds, the coordination sphere of the Cu metal is square-planar. The polymer 1 exhibits strong antiferromagnetic coupling between the paramagnetic Cu(II) metals in the adjacent layers even in the absence of intervening groups.