Two dinuclear copper(II) coordination polymers constructed from m-hydroxybenzoic acid and N-donor ligands: synthesis, crystal structures, and magnetic properties

Two dinuclear Cu(II) complexes, [Cu-2(4,4'-bpy)(m-bza)(4)]center dot 3H(2)O center dot 2DMF 1 and [Cu-2(2,2'-bpy)(2)(m-bza)(3)](NO3) 2 (m-Hbza = m-hydroxybenzoic acid), were synthesized and characterized by X-ray diffraction methods, physicochemical and spectroscopic methods plus magnetic measurements. In complex 1, the paddle wheel binuclear Cu(II) cores are bridged by 4,4'-bpy ligands to form 1D chains which are further assembled into a 3D network through hydrogen bonding, with a topology of (4(4) x 6(10) x 8)(4(4) x 6(2)). The dinuclear Cu(II) clusters in complex 2 are paired to generate hydrogen-bonded tetranuclear motifs, which are assembled via hydrogen bonds into 2D supramolecular layers and further assembled into a 3D supramolecular network through pi a <-pi stacking interactions with topology of (4 x 6 x 8(3) x 10)(4 x 6(2) x 8(3))(6(2) x 8). Variable-temperature magnetic susceptibility measurements show that both complexes exhibit antiferromagnetic coupling exchange.