The activation of molecular oxygen was investigated applying a mixture of iron(II) chloride and N-substituted imidazole ligands. The resulting complexes were characterized and investigated by various techniques, pointing out bimetallic complexes with the general Cl(imidazole)4FeOFeCl3 motif. The complexes contain two different iron centers, on the one hand iron with an octahedral geometry and on the other hand iron with a tetrahedral geometry were observed. Both units are connected via a bridging oxido-ligand. Moreover, the complexes have been applied as precatalyst in iron-catalyzed epoxidation of stilbene.