Syntheses, isolation, and structures of nickel(II) and copper(II) coordination polymers with a tetraaza macrocyclic ligand

The one-dimensional coordination polymers [Ni(L1)(oxalato)]n·nH2O (1) and [Cu(L1)(terephthalato)]n·2nH2O (2) have been synthesized and structurally characterized by a combination of analytical, spectroscopic, and crystallographic methods. The complex 1 exhibits a novel one-dimensional polymeric structure with nickel(II) centers and bridging oxalato ligands. Two important features are observed in 1 when regarding the structure of the oxalato bridge: first, it has an unusual bis-monodentate coordination mode to nickel(II) ions; and second, it is not planar, the distortion arising forms a twisting about the carbon–carbon bond of the oxalato ligand. In 2, the ligand conformation is planar, and the distorted octahedral coordination about the copper(II) ion is completed by two bis-monodentate terephthalato ligands. The copper(II) ions in the complex are bridged by the terephthalato anions to form infinite linear chains, and each chain is linked by interchain hydrogen bonding interactions mediated through water molecules. The presence of water molecules is crucial to lead supramolecular arrays in both complexes.