Two novel coordination polymers with different molecular tectonics based on zinc nitrate and bisimidazole ligand

Abstract

Two new coordination polymers, [Zn(2-mBIM) 2(NO 3) 2(H 2O) 2] n ( 1) and [Zn(BIM) 2(NO 3) 2(H 2O) 2] n (2) (2-mBIM = bis(2-methylimidazol-1-yl)methane, BIM = bis(imidazol-1-yl)-methane), were synthesized by the reactions of Zn(NO 3) 2 with 2-mBIM and BIM ligands. They were characterized by elemental analyses, IR, TGA and X-ray single-crystal diffraction techniques. Each of metal centers in 1 and 2 is coordinated in a slightly distorted tetrahedral geometry by four aromatic nitrogen atoms from four distinct 2-mBIM or BIM ligands, respectively. In compound 1, each pair of neighboring Zn II centers is bridged by two 2-mBIM ligands to form a 16-membered macrometallacyclic structural motif. Each 2-mBIM ligand is coordinated to two Zn II cations and acts as a bridged ligand to form a one-dimensional polymeric cationic chain structure. Compound 2 has a 2D network structure containing 1D channel, thereby each BIM ligand is coordinated to two Zn II cations and thus acts as a bridging ligand. Moreover, each group of four BIM ligands is linked alternatively to each other by four Zn II cations, resulting in a 32-membered macrometallacycle.