The linear regressions found for the CASSCF and NEVPT2 calculations confirm the linear relationship between the squared orbital energy differences and the overall J coupling, validating the principle for extracting exchange and Coulomb interaction differences despite the observed deviations in the fit parameters. Notably, the slopes of the plots nearly double when dynamic correlation effects are incorporated: from -1.5 • 10 -6 cm in the CASSCF calculations to -3.6 • 10 -6 cm in the extended NEVPT2 calculations. Conversely, the yintercept shows an inverted trend, decreasing from +33.8 cm -1 in the minimal CASSCF model to +21.1 cm -1 in the extended NEVPT2 framework. This trends suggests that dynamic correlation effects significantly influence both the antiferromagnetic and ferromagnetic contributions. We attribute the observed deviation from linear behavior in the NEVPT2 calculations with an (8,5) active space to additional dynamic charge polarization introduced when the Cu-O-Cu angle is bent beyond its equilibrium geometry (vide infra).