Transition Metal Complexes of Vitamin B6 Related Compounds. 3. X-ray, Mössbauer, and Magnetic Properties of a Binuclear Iron (III). Complex Containing an Unusual Pyridoxal Derivative


The slow air evaporation of an aqueous solution containing pyridoxal, alanine, and iron(II) perchlorate in a 2:2:1 molar ratio resulted in the precipitation of a dimeric iron(III) complex containing the previously unreported ligand N(PL)2ala2- (IV). We propose that this ligand has resulted from the formation of the Schiff base between pyridoxal and pyridoxamine and the subsequent nucleophilic attack of the Schiff-base imino group upon the α-keto carbon atom of pyruvic acid. The presence of pyruvic acid and pyridoxamine is expected because of the transamination equilibrium catalyzed by the presence of iron(III). The structure of this new ligand was determined through an X-ray structural study of the resulting crystals, which were orthorhombic, Pccn, with a = 13.029 (3), b = 20.052 (4), c = 19.066 (3) Å, and Z = 8. The molecular structure, {[Fe(N(PL)2ala)]ClO4}2·2.6H2O, was found to be disordered in several respects and refinement yielded a final R value of 0.087. The dimeric pseudooctahedral iron(III) structure derives from the bridging of two oxygen atoms from the α-keto groups of the two ligands present. Mössbauer and magnetic measurements indicate the presence of iron(III) ions which are antiferromagnetically coupled (J = -5.2 cm-1) via superexchange through the two bridging oxygen atoms. The structure of this compound is similar to those of several other dimeric iron(III) compounds for which Mössbauer data are also reported. This is the first report of this ligand and the first iron(III) dimer to contain a ligand chelated to each iron ion.



Second Department


Keywords and Phrases

Alanine; Iron; Metal Derivative; Pyridoxal; Drug Comparison; Drug Structure; in Vitro Study; Mossbauer Spectroscopy; Preliminary Communication; X Ray Diffraction

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Article - Journal

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