Syntheses, crystal structures and spectroscopic properties of copper(II)–tetracyanometallate(II) complexes with nicotinamide and isonicotinamide ligands

Abstract

Four new one dimensional (1D) cyanide complexes, namely {[Cu(NH3)4(μ-na)][M′(CN)4]}n and {[Cu(NH3)2(ina)2M′(μ-CN)2(CN)2]}n (M′(II)=Pd (1 and 3) or Pt (2 and 4), na:nicotinamide and ina:isonicotinamide) have been synthesized and characterized by elemental, spectral (FT-IR and Raman), and thermal (TG, DTG and DTA) analyses. The crystal structures of complexes 1–3 have been determined by single crystal X-ray diffraction technique. In complexes 1 and 2, na ligand is coordinated to the adjacent Cu(II) ions as a bridging ligand, giving rise to 1D linear cationic chain and the [M′(CN)4]2− anionic complex acts as a counter ion. Complexes 3 and 4 are also 1D linear chain in which two cyanide ligands bridged neighboring M′(II) and Cu(II) ions, while ina ligand is coordinated Cu(II) ion through nitrogen atom of pyridine ring. In the complexes, the Cu(II) ions adopt distorted octahedral geometries, while M′(II) ions are four coordinated with four carbon atoms from cyanide ligands in square-planar geometries. The adjacent chains are further stacked through intermolecular hydrogen bond, NH⋅⋅⋅π, CH⋯M′ and M′⋯π interactions to form 3D supramolecular networks. Vibration assignments are given for all the observed bands. In addition, thermal stabilities of the compounds are also discussed.