Trinuclear cobalt(II) and binuclear iron(III) complexes with unsymmetricaltetradentate Schiff-base ligands derived from 3-formylsalicyclic acid: Synthesis, magnetic, spectroscopic and Mossbauer investigations

Two Schiff bases, 3-((N-2-carboxyphenyl)formimidoyl)salicylic acid, H(3)fsa amb, and 3-((N-2-carboxyethyl)formimidoyl)salicylic acid, H(3)fsaala which are obtained by condensation of 3-formylsalicylic acid with 2-aminobenzoic acid and beta -alanine respectively, are used as ligands for the design of homotrinuclear metal(II) and homodinuclear metal(III) complexes. The metal centers are bridged by carboxylic and/or phenolic oxygen atoms. Three new c ompounds, [Co-3(fsaamb)(2)(H2O)(6)], [Co-3(fsaala)(2)(H2O)(6)], and [Fe-2(f saamb)(2)(H2O)(2)], have been synthesized by reacting the above Ligands wit h the appropriate metal perchlorates in slightly basic solutions. The IR sp ectra show that the ligands act in a tetradentate manner, coordinating thro ugh the imino, phenolato,and the two carboxylato groups. The stereochemistr y of the metal ions in the three compounds is assigned according to the mag netic and UV/VIS spectroscopic data. The Fe(III) derivative has been also c haracterized by Mossbauer spectroscopy (delta = 0.67 mm s(-1) and DeltaE(q) = 0.94 mm s(-1) at 300 K; delta = 0.77 mm s(-1) and DeltaE(q) = 0.93 mm s( -1) at 80 K).