Model 1 introduces four seven-membered rings attached to the pyrrolic carbon atoms farthest from the iron ion, resulting in a planar model. Model 2 incorporates four seven-membered rings at one side of the pyrrolic rings, resulting in a saddle structure. Model 3 features two seven-membered rings bridging two pyrrolic rings, resulting in an overall convex structure. The coordination geometries of the central iron differ slightly in the three models. The longest Fe-N bonds are found in 2 (1.972 Å), followed by 1 (1.956 Å) and 3 (1.911 Å). The N-Fe-N angles of opposite nitrogen atoms are close to linear in all structures (1: 180°, 2: 177°, 3: 174°). The convex structure of 3 leads to a small displacement of the iron ion from the plane spanned by the four nitrogen atoms (ca. 0.102 Å, see Table for all structural parameters).