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

One reported compound [Co(PDA)(4,4′-bipy)]·nHO and one new compound [Co(PDA)(Im)(HO)]·nHO were prepared by the reactions of Co(NO)·6HO or Co(OH) with 1,4-phenylenediacetic acid (HPDA) 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)]·nHO results in a μ-bridging mode of the PDA ligand with one μ-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)(HO)]·nHO helps to construct a one dimensional chain with the two carboxylato groups of PDA ligand in monodentate coordination modes. The magnetic studies reveal the presence of dominant antiferromagnetic interaction in [Co(PDA)(4,4′-bipy)]·nHO with a field-induced magnetic transition due to spin-flop. Magnetically, [Co(PDA)(Im)(HO)]·nHO 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 and therefore the resulting frameworks and their magnetic properties. [ABSTRACT FROM AUTHOR]