A new tetranuclear copper(II) complex using a Schiff base ligand: Synthesis, structural, and magnetic studies

This paper reports on the synthesis, X-ray, and magnetic properties of tetranuclear Cu^II complex [CuL₄] with square-like structure. A Schiff base ligand used for synthesis in this work derives from condensation of acetylacetone with DL-valine amino acid. The structure of the synthesized ligand was investigated by FTIR and NMR. Investigation of the crystal packing diagrams demonstrates extensive C–H⋯O interactions of hydrogen bonding, causing to the production of network structures. The complex exhibits exchange interaction among the Cu^II ions by a bridging carboxylate pathway. Analysis of the magnetic data through spin Hamiltonians of the form Ĥ=-2J(Ŝ₁Ŝ₄+Ŝ₄Ŝ₂+Ŝ₂Ŝ₃+Ŝ₃Ŝ₁)-2J^′(Ŝ₁Ŝ₂+Ŝ₃Ŝ₄) (J has a positive value for a ferromagnetic interaction and negative value for an antiferromagnetic interaction) lead to the following parameters set of best-fit: J = 3.04 cm⁻¹, J′ = 0 cm⁻¹, g = 2.09, and ZJ = −0.109 cm⁻¹.