Synthesis and chemical reactivity of an Fe(III) metallacrown-6 towards N-donor Lewis bases

The iron(III) 18-azametallacrown-6 [Fe(ashz)(EtOH)](6) (1) (ashz(3-) = trianionic derivative of N-acetylsalicylhydrazide), prepared upon reaction of [Fe-3(mu(3)-O)(Piv)(6)(H2O)(3)](Piv) (Piv=(BuCOO-)-C-t). with H(3)ashz, reacts with N-heterocyclic Lewis bases (B=pyridine, 4-methyl pyridine, 3-amino pyridine or imidazole), leading to the stable adducts [Fe(ashz)(8)](6) (2 to 5, respectively) upon replacement of the labile ethanol ligand. All the compounds were characterized by elemental analysis, IR and ESI-mass spectroscopies and, for complexes 1 and the 3-amino pyridine adduct 4, also by X-ray crystallography. In both 1 and 4, the stereochemistry of the ligand imposes a propeller configuration of the metal cation which exhibits alternating Lambda/Delta forms. (C) 2013 Elsevier B.V. All rights reserved.