A rational synthetic route leading to neutral linear homotrinuclear complexes: Design of Ni(II), Cu(II) and Zn(II) trinuclear complexes using a new tetradentate Schiff-base ligand derived from 3-formylsalicylic acid

A new unsymmetrical tetradentate Schiff-base ligand, 3-(N-(carboxyethyl)for mimidoyl)salicylic acid (H(3)fsaala), was synthesized by condensation of 3- formylsalicylic acid with beta-alanine. The new ligand was characterized by means of chemical analysis, IR, H-1- and C-13-NMR spectroscopies. This pot entially trianionic ligand is suitable for the design of linear homotrinucl ear complexes. Three neutral compounds, [Ni-3 (fsaala)(2)(H2O)(6)], [Cu-3(f saala)(2)(H2O)(6)] and [Zn-3(fsaala)(2)], were prepared by reacting the lig and with the appropriate metal(II:) perchlorates in slightly basic solution s. The IR spectra show that the ligand acts in a tetradentate manner, coord inating through its imino, phenolate and the two carboxylato groups. The st ereochemistry of the metal ions in these compounds is discussed according t o the magnetic and spectroscopic data. The Zn(II) derivative was characteri zed also by H-1-NMR spectroscopy.