Effects of the Auxiliary Ligands on the Structures of Diphenate Complexes: From 1D Helical Chain to 2D Network

Two coordination polymers, [Cd(dpa)(L1)] (1) and [Cd(dpa)(L2)]center dot CH(3)CH(2)OH(3) (2) (L1 = 2,6-bis(1H-benzimidazol-2yl)-pyridine, L2 = 2,2'-(1,4-butanediyl) bis (1H-benzimidazole) (L2), both of which contain helical chain subunits, were synthesized by the reaction of Cd(II) salts and diphenic acid (H(2)dpa) with rigid, chelating and flexible, bridging auxiliary ligands, respectively. Compound 1 has a ID helical chain structure, in which dpa(2-) as bridging ligand is responsible for the formation of the main framework and L1 as chelating ligand grafts on one side of the helical chain. This structure is further extended into a 3D supramolecular framework through two kinds of strong hydrogen bonding interactions. Compound 2 has a 2D structure, in which dpa(2-) bridges the Cd(II) atoms into helical chains and L2 bridges the left- and right-handed chains into a racemic layer with a [4,4] topology.