Synthesis, crystal structure and antiradical effect of copper(II) Schiff base complexes containing five-, six- and unusual seven-membered rings

The synthesis and solid-state structure of mononuclear copper(II) complexes [Cu(SAIB)(H2O)2] (1), [Cu(SBAIB)(H2O)2]·H2O (2) and [Cu(SGABA)(H2O)2] (3) are described. Schiff base ligands H2SAIB, H2SBAIB and H2SGABA chelate the copper(II) ion in an O,N,O tridentate fashion. The square-pyramidal geometry of the final complexes is completed by two water ligands. The formation of an unusual seven-membered ring in the set of copper(II) N-salicylidene-aminoacidates is reported. Compounds 1–3 were evaluated by the antiradical activity assay.