Synthesis, structural characterization and magnetic properties of new tripeptide Schiff base heterotrinuclear Cu(II)–M(II)–Cu(II) (MZNi and Mn) complexes

Two novel heterotrinuclear Cu(II)-M(II)-Cu(II) (MZNi and Mn) complexes, [Ni(H2O)4(CuL)2]$7H2O (1), [Mn(H2O)4(CuL)2]$8H2O (2), have been obtained by the self-assembly of the mononuclear tripeptide Schiff base complexes [CuL]K with bivalent metal ion M2C, where H3LZN-salicylideneglycylglycylglycine. Single crystal X-ray diffraction experiments indicate that the structures both 1 and 2, are made up of centrosymmetric trinuclear units with the M atom lying on an inversion center, formed the 1D supramolecular chain structures via hydrogen bondings and M/O weak interactions. The magnetic susceptibility data (2–300 K) revealed antiferromagnetic interactions between copper(II) ions and the central metal. The magnetic susceptibility data were quantitatively analyzed using the theoretical expressions deduced from the spin Hamiltonian for a symmetrical three-spin system ^H ZK2J^SMð^SCuð1ÞC^SCuð2ÞÞ to give the coupling parameters JCuNiZK0.46 cmK1 and JCuMnZK0.15 cmK1. q 2005 Elsevier B.V. All rights reserved.