Co(II)/Ni(II) Coordination Polymer of Isomeric Terphenyl-2,2",4,4"-tetracarboxylic Acids with a Single Water Bridge: Syntheses, Structures, and Magnetic Properties

Two single water-bridged Co(II)/Ni(II) chains coordination polymers, namely [Co(m-H(2)tpta)(H2O)(3)](n) (1) and {[Ni-2(p-tpta)(H2O)(6)]center dot 2H(2)O}(n) (2) were synthesized based on isomeric terphenyl-2,2 '', 4,4 ''-tetracarboxylic acid (m-H(4)tpta and p-H(4)tpta) ligands under hydrothermal conditions. They have been structurally characterized by FT-IR, elemental analysis, single-crystal, and powder X-ray diffraction analysis. Structurally, the central metal ions display slightly distorted octahedral geometries in 1 and 2, and are linked to 1D metal chains by single bridging water molecules. The isomeric H(4)tpta ligands coordinate metal ions in different mu(1)-eta(1):eta(0):eta(1):eta(0) and mu(4)-eta(1):eta(1):eta(1):eta(1) coordination modes, leading to the formation of 1D chain and 3D network structure. Complex 2 displays a 3D network with (4,4)-connected NbO net topology. Magnetically, complex 1 exhibited an antiferromagnetic interaction through mu(2)-H2O in the uniform Co(II) chain model. Complex 2 also showed an antiferromagnetic coupling between Ni(II) ions corresponding to magnetic coupling Ni-Ow-Ni angles.