Decomposition of Magnetic Coupling in μ-Oxo-Bridged Metal Complexes

The valence intermediate effective Hamiltonian (VIEH) approach is a powerful tool for decomposing an overall magnetic coupling strength into ferromagnetic and antiferromagnetic contributions. Herein, we suggest an adaptation of the VIEH framework for complexes with multiple magnetic coupling pathways. This approach is showcased with a homologous series of [M2(μ–O)(NH3)n]2+ complexes, including Cu(II), Ni(II), and Fe(II). Typically, antiferromagnetic coupling progressively weakens from copper to nickel and iron. We demonstrate that this weakening arises primarily from an increase in the ferromagnetic coupling contribution relative to the antiferromagnetic one.