Studies on the magnetic properties of two cobalt(II) complexes bearing 1,4-phenylenediacetate ligands

One reported compound [Co(PDA)(4,4'-bipy)](n)center dot nH(2)O and one new compound [Co(PDA)(Im)(2)(H(2)O)(2)](n)center dot nH(2)O were prepared by the reactions of Co(NO(3))(2)center dot 6H(2)O or Co(OH)(2) with 1,4-phenylenediacetic acid (H(2)PDA) in the presence of the ancillary ligands 4,4'-bipyridine (4,4'-bipy) or imidazole (Im), and their magnetic properties were investigated. The presence of 4,4'-bipy in [Co(PDA)(4,4'-bipy)](n)center dot nH(2)O results in a mu (3)-bridging mode of the PDA(2-) ligand with one mu (2)-carboxylato group and one chelating carboxylato group and the construction of a 2D framework as reported in the literature. The introduction of Im ligand in [Co(PDA)(Im)(2)(H(2)O)(2)](n)center dot nH(2)O helps to construct a one dimensional chain with the two carboxylato groups of PDA(2-) ligand in monodentate coordination modes. The magnetic studies reveal the presence of dominant antiferromagnetic interaction in [Co(PDA)(4,4'-bipy)](n)center dot nH(2)O with a field-induced magnetic transition due to spin-flop. Magnetically, [Co(PDA)(Im)(2)(H(2)O)(2)](n)center dot nH(2)O presents a mononuclear structure. This work reveals that the introduction of ancillary ligands in the Co(II)-PDA system adjusts the linking modes of PDA(2-) and therefore the resulting frameworks and their magnetic properties.