Computational Characterization of Multifunctional Magnetic Complexes

Supramolecular assemblies of distinct magnetic centers are intriguing candidates for molecular-level ingredients of magnetic materials for quantum information technologies. Examples of interest here are qubits between spin-crossover centers. Development to serve as the required building blocks for scalable communication and information storage requires accessible long-term stability and detailed knowledge of structure-property relationships. Use of 3d transition metals in the active centers allows for the creation of strongly coupled spin interactions between metallic centers that may be exploited both for information storage and for signal transfer. We discuss a series of such assemblies [Angew. Chem. Int. Ed. 130, 13697 (2018); Chem. Commun. 58, 5375 (2022)] for which we have calculated the thermal evolution of the magnetic susceptibility for the parallel and anti-parallel spin interactions between the spin-crossover centers. We find reasonable agreement with experimental trends, with absolute values over-estimated because of limited vibrational sampling. From the calculated total energies for various magnetic configurations, we have fit a model spin Hamiltonian for which we find reasonable parameter comparison with experimental values.