Synthesis, structural characterization and magnetic properties of a novel metallacrown [Fe 6(amshz) 6(C 3H 7NO) 6]·6CH 3OH

The novel 18-metallacrown-6 metallamacrocycle, with the formula of [Fe ₆(amshz) ₆(C ₃H ₇NO) ₆]·6CH ₃OH ( 1), has been synthesized by the self-assembly reaction of iron ions with N-substituted salicylhydrazide ligands. Six Fe(III) ions and six deprotonated N-acetyl-3-methylsalicylhydrazide (amshz ^3-) ligands construct a planar 18-membered ring based on Fe-N-N-Fe linkage. Due to the coordination, the ligand enforces the stereochemistry of the Fe ³⁺ ions as a propeller shape with alternating …∆Λ∆Λ… configurations. There exists a strong antiferromagnetic exchange interaction with μ_eff = 12.54 μ_B at 300 K between the Fe(III) spin 5/2 centers.