Preparation, crystal structures and magnetic properties of hetero- and homo-metallic coordination polymers with triazacyclononane derivatives bearing propionic acid pendant arms

Two Cu(II)-Na(I) hetero-metallic coordination polymers [Cu2Na5(tacntp)(2)(H2O)(9)](ClO4)(3)center dot 2H(2)O (1) and [Cu2Na5(tacntp)(2)(H2O)(9)](ClO4)(3)center dot 2H(2)O (2) were constructed from Cu(II) salts and a trisubstituted N-propionic acid functionalized ligand, namely 1,4,7-triazacyclononane-1,4,7-tripropionic acid (tacntpH(3)). In complex 1, the Na+ ions act as nodes, being surrounded by six [Cu(tacntp)](-) moieties resulting in a 2D coordination polymer. In complex 2, Na+ ions are bridged by pendant carboxylate groups and water ligands to give a 1D Na-O inorganic polymeric ribbon, which is expanded into a complicated 2D hetero-metallic array through the connecting [Cu(tacntp)](-) units. The differences between the two structures are related to the amount of Na+ ions present in the reaction media. In further experiments, the trisubstituted pro-ligand tacntpH(3) underwent a hydrothermal Cu(II)-induced cleavage of one of three pendant arms, and the resultant disubstituted pro-ligand tacndpH(2) assembled with Cu(II) to give a 1D homo-metallic zigzag chain compound [Cu(tacndp)]ClO4 center dot H2O (3). Magnetic susceptibility measurements on complex 3 revealed a ferromagnetic interaction between the Cu(II) centers within the 1D chain.