Synthesis, crystal structure and magnetic properties of a novel tripeptide Schiff base heterotrinuclear complex with 1D supramolecular structure

A novel tripeptide Schiff-base heterotrinuclear complex, [Co(H2O)(4)(CuL)(2)] center dot 4H(2)O (1) (H3L = N-5-bromosalicylideneglycylglycylglycine) has been synthesized and characterized by elemental analyses, IR and electronic spectra. Single-crystal X-ray diffraction analysis showed that the molecular structure is made up of centrosymmetrical trinuclear units with the Co atom lying on an inversion center. Through Cu center dot center dot center dot O and Cu center dot center dot center dot Br weak interactions and hydrogen bonds, the 1D supramolecular chain structure is formed. The magnetic susceptibility data (2-300 K) revealed antiferromagnetic interactions between copper(II) ions and the central metal cobalt( II) ions. The magnetic susceptibility data were quantitatively analyzed using the theoretical expressions deduced from the spin Hamiltonian for a symmetrical three-spin system (H) over cap = -2J (S) over cap (Co)((S) over cap (Cu(1)) + (S) over cap (Cu(2))) to give the coupling J(CuCo) = -2.26 cm(-1).