To evaluate the effect of model size on the geometries and electronic structures, the graphene-like environment was enlarged for all three models, see Figure . The increased planarity of the carbon structure does not lead to a change in the local ligand environment (maximum change in Fe-N distance: 0.024 Å for 2). In the extended models 1 Large -3 Large , the most stable spin state remains intermediate spin. Notably, for models 1 Large and 2 Large , the energy gap to the less stabilised spin states decreases with increasing ligand π-system: the high spin and low spin states are destabilised by less than 3 kcal mol -1 in the extended models. In contrast, the low spin and the high spin state are destabilized even further in 3 Large than in its smaller counterpart. This different behavior can be explained by spin density being distributed onto the carbonbased ligand in the low spin and high spin states of 1 and 2, leading to the iron nucleus still behaving as an intermediate spin state, which explains the similar properties. Meanwhile, the spin density remains on iron for 3 and therefore has a stronger influence on the properties. The intermediate spin ground states have essentially the same electronic configurations as in the smaller models, except for some changes in orbital composition. Specifically, in 1 Large , there is a more pronounced admixture of ligand character into the degenerate d xz and d yz orbitals (see Figures ). The electronic structure changes in 2 Large and 3 Large are interlinked with the visually apparent flattening of the extended models. This aspect will be discussed in more detail below.