Regarding the convergence of spin states and Mössbauer properties, we showed that molecular models should incorporate at least two complete rings of carbon atoms around the FeN 4 unit, while periodic models should have at least a size of 6×6. Most importantly though, we identified several types of electronic structure that are relevant for iron in FeNCtype environments. Besides the expected low spin, intermediate spin and high spin configurations in which the unpaired electrons are confined to the d-orbitals, we found energetically relevant electronic structures with unpaired electrons in the carbon environment. These may be a result of intramolecular redox events, i.e. reduction or oxidation of the graphene πsystem leading to a net electron transfer from or to the iron ion, or ferromagnetic or antiferromagnetic coupling between a formal triplet configuration of the graphene π-system with the unpaired electrons in the iron d-orbitals.