The relative stability of high‐spin and low‐spin states has been studied in a series of Fe(II) complexes with model ligands of different σ donation strength. The natural (delocalized) orbitals are transformed to atomic‐like orbitals to analyze the multiconfigurational wave function in a valence bond picture. This analysis reveals a direct relation between the stabilization of the low‐spin state and the importance of the ligand‐to‐metal charge transfer in the σ orbitals. The multiconfigurational second‐order perturbation theory (CASPT2) energy dependence of the low‐spin state as function of the Fe‐ligand distance deviates significantly from coupled cluster (CCSD(T)) calculations. This is ascribed to the intrinsic multiconfigurational character of the wave function of the low‐spin state, invalidating the use of the simple closed‐shell reference in the coupled cluster calculations. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010