Oxo-and hydroxo-bridged oligonuclear metal centers are structural motifs commonly encountered in inorganic and bioinorganic chemistry. In these magnetic complexes, unpaired electrons localised at transition metal centers can interact either through direct exchange, where the d orbitals of different metal sites overlap spatially, or through superexchange mechanisms (Figure ). These kinds of mechanism are indirect magnetic interactions mediated by doubly occupied ligand orbitals that bridge the metal centers, enabling spin alignment through virtual electron hopping. For example, a previous study on the [Mn(III) 2 (µ-O)(µ-OAc) 2 (Me 3 tacn) 2 ] 2+ complex identified three significant superexchange pathways: two symmetric π pathways involving orbitals perpendicular to the Mn 2 O 2 plane and a mixed in-plane σ/π pathway. In general, direct exchange is much more rare for oligonuclear metal complexes than superexchange. Taking together both mechanisms over all pairs of magnetic orbitals influences whether the spins on the transition metal centers align parallel, resulting in ferromagnetic coupling, or antiparallel, resulting in antiferromagnetic coupling. (a) 180 The sum of all two electron interactions in magnetically coupled systems is usually quantified with the phenomenological Heisenberg-Dirac-van Vleck-Hamiltonian (eq. 1). ĤHDvV = -2