Syntheses and characterization of ZnII and CdII coordination polymers, [Zn(μ-bpe)(NO2)2]n and [Cd2(μ-bpp)3(NO2)4]n

Two new ZnII and CdII coordination polymers of trans-1,2-bis(4-pyridyl)ethene (bpe) and 1,3-di(4-pyridyl)propane (bpp) with anionic nitrite ligands, [Zn(mu-bpe)(NO2)2]n (1) and [Cd2(mu-bpp)3(NO2)4]n (2) have been synthesized and characterized by elemental analysis, IR-, 1H NMR- and 13C NMR spectroscopy and studied by X-ray crystallography. The structural studies of (1) and (2) show the compounds are one- and three-dimensional polymers with coordination environments of distorted octahedral and pentagonal bipyramide, ZnN2O4 and CdN3O4, respectively. Self-assembly of these compounds in the solid state via pi-pi-stacking interactions is discussed.