Structures and magnetic properties of one-dimensional polymers constructed with copper(II) salts and pyridinecarboxamide-type ligands

Three complexes of the composition {[Cu(μ1,5-dca)2(mppca)2] · H2O}n (1), [Cu(μ1,5-dca)2(nppca)2]n (2) and [Cu(μ-Cl)2(mppca)2]n (3) (dca = dicyanamide, N(CN)2-; mppca = N-(4′-methylphenyl)-4-pyridinecarboxamide; nppca = N-(4′-nitrophenyl)-4-pyridinecarboxamide) have been synthesized and characterized by single crystal X-ray crystallography and magnetic susceptibility studies. Different supramolecular structures of the complexes have been constructed by different non-covalent motifs in the crystalline solids. In complex 1, adjacent copper(II) atoms are connected by double μ1,5-dca(end-to-end) bridges to form a chain-like structure. The chains are linked by π–π interactions and hydrogen bonds between the ligands and water molecules to form a 3D network. In complex 2, copper(II) atom has a coordination environment similar to 1, but water molecules have not been found. Weak C–H⋯N hydrogen bonding and π–π interaction yield a 3D supramolecular network which is different from that of complex 1. Complex 3 is a 1D polymeric chain in which Cu(II) ions are bridged by Cl−, and only CH/π interactions had been found. Magnetic measurements revealed antiferromagnetic properties of 1, 3 and ferromagnetic behavior of 2.

Graphical abstractThree N(CN)2- or Cl− bridged 1D copper(II) complexes have been synthesized with the pyridinecarboxamide ligand. The pyridinecarboxamide ligands exhibit interesting intermolecular contacts. Temperature dependence of magnetic susceptibilities of the complexes has been studied.Figure optionsDownload full-size imageDownload as PowerPoint slide