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

摘要

Three complexes of the composition {[CU(mu(1.5)-dca)(2)(mppca)(2)] (.) H2O}(n) (1), [Cu(mu(1,5)-dca)(2)(nppca)(2)](n) (2) and [Cu(mu-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 mu(1.5)-dca(end-to-end) bridges to form a chain-like structure. The chains are linked by pi-pi 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 pi-pi 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/pi interactions had been found. Magnetic measurements revealed antiferromagnetic properties of 1, 3 and ferromagnetic behavior of 2. (c) 2005 Elsevier B.V. All rights reserved.