Crystal Structures, Magnetic Properties, and Theoretical Investigations of Three Linear Cluster Complexes with Pyridine-2-Amidoxime

Abstract

Three novel trinuclear mixed-transition-metal complexes of Fe(III), Co(III, II), Ni(II) and Cr(III)), with pyridine-2-amidoxime (Hpa) ligand are synthesized, i.e. [FeNi₂(pa)₆]Cl·15H₂O (1), [CrNi₂(pa)₆]OH·5H₂O (2), and [CoCo₂(pa)₆]NO₃ (3). These complexes are characterized by variable-temperature magnetic susceptibility, electrochemistry, and single crystal X-ray diffraction methods. 1 and 2 are heteronuclear metal clusters in the perfect linear arrangement, i.e. [Ni^II⋯Fe^III⋯Ni^II and [Ni^II⋯Cr^III⋯Ni^II] respectively, while 3 is linear [Co^II⋯Co^III⋯Co^II] trinuclear. Theoretical calculations are employed to successfully account for the experimental results of the variable temperature magnetic susceptibility.