Expanding the active space and incorporating dynamic correlation effects in NEVPT2 enhances the electronic structure description by perturbatively accounting for excitations into higher-lying orbitals, such as the 4d double-shell orbitals. This adjustment brings J NEVPT2 closer to the J Yamaguchi values. Despite the differences between the CASSCF, NEVPT2, and ting procedure. It is expected that larger active spaces combined with NEVPT2 will account for missing dynamic correlation, aligning the results more closely. As highlighted in the fundamental review by Roald Hoffmann, the magnetic interaction in this system consists of one ferromagnetic and one antiferromagnetic component. By applying a linear regression analysis to the magnetic coupling using equation 4, the exchange interaction and the difference in intra-and inter-site Coulomb interactions between the gerade and ungerade σ orbitals can be extracted. These values can then be used to quantify the strength of the ferromagnetic and antiferromagnetic contributions along the σ-coupling pathway. The resulting variations in magnetic coupling as a function of the squared orbital energy difference (ε i -ε j ) 2 for all CASSCF and NEVPT2 scans are shown in Figure , which highlights clear linear correlation regimes across all four fits.