The electronic structure of [OsF6]2− and PtF6 complexes was studied by means of CASSCF/NEVPT2 multiconfigurational calculations, including spin–orbital coupling, which is very relevant in the case of these metals. From these calculations, it is possible to establish that in the octahedral symmetry (Oh), the ground state is non-magnetic (Jeff = 0) because of the strong ligand field, and the interaction with paramagnetic excited states is almost negligible, resulting in a non-magnetic behavior, which is in agreement with the experimental evidence.