Metal-dependent assembly and structure of metal 1,4-phenylenediacetate complexes with 1,10-phenanthroline

Three new complexes, [Cu(PDA)(phen)] · 2H2O (1), [Zn(PDA)(phen)(H2O)] (2) and [Mn(PDA)0. 5(phen)(H2O)3] · (PDA)0.5 · (H2O)0.25 (3), were obtained by reactions of metal ions with flexible ligand 1,4-phenylenediacetic acid (H2PDA) and auxiliary ligand 1,10-phenanthroline (phen) under solvothermal conditions. They have been characterized by single-crystal X-ray diffraction, elemental analysis, IR spectrum and thermal analysis. Single-crystal X-ray diffraction analysis shows that the structures of complexes 1-3 are completely different. In complex 1, Cu(II) ion is four-coordinated, and Cu(II) ions are bridged by PDA ligands into 1D chains. Both complexes 2 and 3 are dimers, but in complex 2, Zn(II) ion is five-coordinated and two Zn(II) ions are linked by two PDA ligands with cis-configuration, resulting in a cyclic structure. While in complex 3, Mn(II) ion is six-coordinated and two Mn(II) ions are bridged by one PDA ligand co-operated with the terminal ligand phen, forming a dimer. Therefore, radius and thus coordination number of metal ions take a decisive role in the construction of complexes 1-3.