Syntheses, crystal structures, spectroscopic properties and thermal decompositions of one dimensional coordination polymers with 4-(2-aminoethyl)pyridine and cyanide ligands: [M(μ-4aepy)2(H2O)2][M′(CN)4] (M = Cu or Zn, M' = Ni or Pd)

Abstract

Two new one-dimensional coordination polymers, [Cu(μ-4aepy)2(H2O)2][Ni(CN)4] (1), and [Zn(μ-4aepy)2(H2O)2][Pd(CN)4] (2) [4aepy = 4-(2-aminoethyl)pyridine] have been synthesized and characterized by vibrational (FT-IR and Raman) spectroscopy, single crystal X-ray diffraction, together with the thermal and elemental analyses techniques. The structural analyses revealed that complexes 1 and 2 are isomorphous and isostructural, and have polymeric 1D networks. The Ni(II) or Pd(II) atoms exhibit the usual square-planar geometries with the cyanide ligands. The coordinations around the Cu(II) or Zn(II) atoms are slightly distorted square-planar arrangements, while the slightly distorted octahedral coordinations are completed by the symmetry related water O atoms in the axial positions. The M(II) ions [M(II) = Cu(II) in 1 and Zn(II) in 2] are bridged by 4aepy ligands to generate [M2(C7H10N2)2] metalloligands. The combinations of [M2(C7H10N2)2] metalloligands produce one-dimensional structures of the complexes. In the crystal structures of both complexes, the overall three-dimensional networks are expanded by the combinations of M′···π [M′(II) = Ni(II) or Pd(II)] interactions with the intermolecular OH⋯N, OH⋯O and CH⋯O hydrogen bonds. The vibrational spectral data are very much consistent with the structural data presented of the complexes. Thermal stabilities and decomposition products of the complexes were investigated in the temperature range of 40–800 °C in the static air atmosphere.