Effect of the size of aromatic chelate ligands on the frameworks of metal dicarboxylate polymers: From helical chains to 2-D networks

To investigate the influence of the size of the aromatic chelate ligands on the frameworks of metal dicarboxylate polymers, four new coordination compounds [Co(phen)(oba)](n)center dot 0.5nH(2)O (1), [Ni(phen)(oba)](n)center dot 0.5nH(2)O (2), [Co-2(H2O)(TATP)(2)(oba)(2)](n)center dot 2nH(2)O (3), and [Ni-2(H2O)(TATP)(2)(oba)(2)](n)center dot 2nH(2)O (4) (phen = 1,10-phenanthroline, TATP = 1,4,8,9-tetranitrogen-trisphene, oba = 4,4'-oxybis(benzoate)) have been synthesized under similar conditions and structurally characterized by elemental analysis, IR, and X-ray crystallography. In the isomorphous 1 and 2, the metal centers are linked by bridging oba ligand to form I-D helical chains, whereas the isomorphous 3 and 4 have extended 2-D arrays. The differences among these structures indicate that the size of the rigid aromatic chelate ligands have important effects on the structures of their complexes.