Abstract The equilibrium geometries of rutile type FeF₂ and MgF₂ are determined using precise density functional theory calculations that lead to good agreement with experimental data. The strong deviation from the “ideal” octahedral geometry in FeF₂ comes from the Fe²⁺ ion with the d ⁶ configuration in the high-spin state, which would require a singly occupied spin-down d orbital. The stability can only be understood by going beyond the first coordination shell considering direct Fe–Fe interactions mainly along the c-axis. The orbital population of the various Fe-d orbitals is analyzed using constarint distortions between the ideal and the equilibrium structure. Above a critical Fe–Fe distance of about 3.15 Å the population numbers change drastically, a single Fe-d spin down orbital becomes occupied and the system can relax to an insulating state. In MgF₂ no such d-orbitals are present and thus the distortions are much smaller.