Three novel octanuclear, hexanuclear and tetranuclear complexes of high-spin Fe(III) ions were obtained by the reaction of the N,N′-bis-(1R-imidazol-4-ylmethylene)-ethane-1,2-diamine ligand (R = H, CH3) and its derivatives with Fe(ClO4)3·6H2O and KSCN. The tetradentate Schiff-base ligand acts as a bis(bidentate) chelating bridge between two adjacent high-spin Fe(III) centers. The presence of a methyl group in the imidazolyl substituent, the change of counterions or the replacement of imidazole by pyridine has a drastic effect on the nuclearity of the cluster. The magnetic properties of all compounds exhibit antiferromagnetic interactions via μ-oxo or μ-hydroxo pathways in Fe(III) dimers.