Synthesis, crystal structures and magnetic properties of a novel fused 9-metallacrown-3 and a high/low spin [Fe(pao)2]3·H2O

Two ferric complexes, [Fe6(pao)6(OAc)6]·H2O (1) and [Fe(pao)2]3·H2O (2) (Hpao = Picolinaldehyde, oxime), have been prepared through the method of hydrothermal and solvent diffusion, and characterized by elemental analysis, IR spectra, XRD, single crystal X-ray diffraction and TG analysis. Complex 1 shows a novel fused metallacrown ether 9-MC-3 with [–O–N–] bridges. Two 9-MC-3 are fused together by sharing one oximato O atom and one bridging acetyl group, giving a double disc wheel structure. Complex 2 exhibits a linear trinuclear example with two terminal Fe2+ centers of low spin (LS) state and the central Fe2+ ion of high spin (HS) state. Variable-temperature magnetic susceptibility study reveals that complex 1 has an overall anti-ferromagnetic coupling behavior and complex 2 shows a weak ferromagnetic coupling interaction.