Synthesis and characterization of iron(III) complexes of N-4 Schiff base macrocycles

Iron(III) complexes of the diprotic N-4 Schiff base macrocycles, 7,8,15,16, 17,18-hexahydrow-dibenzo [e,m] [1,4,8,11] tetraazacyclotetradecine (H-2(2,2 mac)) and 8,9,16,17,18,19-hexahydro-7H-dibenzo [e,n] [1,4,8,12] tetraazacy clopentaadecine (H-2(3,2mac)),were prepared by the metathesis reaction of a nhydrous iron(III) bromide with the disodium or magnesium complexes of the dianionic ligands in THF under an inert atmosphere. The complexes exhibit t he intermediate spin state as evidenced by magnetic susceptibility and Moss bauer spectroscopy. Fe(3,2 mac)Br is structurally characterized as a distor ted square pyramid with the four nitrogen atoms in the basal positions and the bromide occupying the axial site. The average iron to nitrogen bond dis tance is 1.921 Angstrom. (C) 1999 Elsevier Science S.A. All rights reserved .