UNLOCKING THE FUNCTIONAL POTENTIAL OF BIS(PHENYLHYDRAZONES): SYNTHESIS AND STRUCTURAL ELUCIDATION OF THE FIRST FE(II) COMPLEX WITH A 2,6-DIACETYLPYRIDINE-BASED LIGAND

Abstract

The reaction of a warm methanolic solution of iron(II)-bromide and an acetone solution of 2,6-diacetylpyridine-bis(phenylhydrazone) (L) gave dark red prismatic single crystals of the complex [FeL2]Br2. The composition and purity were elucidated via elemental analysis, and the coordination mode was determined based on FTIR spectra. The latter was confirmed by X-ray structural analysis. This complex is isostructural with previously synthesized complexes [CuL2]Br2 and [CoL2]I2 – all three complexes crystallize in the C2/c space group and have very similar unit cell parameters. [FeL2]2+ lies on a two-fold rotation axis; thus, the asymmetric unit consists of one ligand molecule, a half of the Fe(II) ion, and one bromide ion. Fe(II) is situated in a very distorted octahedral environment formed by six nitrogen atoms of two ligand molecules, with trans-angles having the values of 146.81° and 173.43°. Due to steric factors, the phenyl rings of the ligand are twisted, which can be seen from the torsion angles of 141.42° for one and 155.27° for the other phenylhydrazone moiety. Besides, the complex is characterized by coupled TG-MS measurements.
Keywords: metal complexes, hydrazones, synthesis, characterization.