There are several contributing factors for the deviations between the CASSCF and NEVPT2 results in the dihedral scans. In the (14,11) NEVPT2 calculations for the iron complex, antiferromagnetic couplings are incorrectly fitted as well as ferromagnetic due to missing hole-particle excitations in the fitting equation. As discussed further above additional dynamic correlation effects also play a role. For future quantitative analyses of ferromagnetic and antiferromagnetic components, these missing factors must be considered. Moreover, in complexes with iron or manganese that have up to five unpaired electrons per magnetically active center, the ferromagnetic and antiferromagnetic contributions will become so small that the effect of the isotropic biquadratic term on the overall magnetic coupling should be included in a decomposition analysis of magnetic coupling paths.