Electrically Switchable Magnetic Molecules: Inducing a Magnetic Coupling by Means of an External Electric Field in a Mixed-Valence Polyoxovanadate Cluster

Herein we evaluate the influence of an electric field on the coupling of two delocalized electrons in the mixed‐valence polyoxometalate (POM) [GeV14O40]8− (in short V14) by using both a t‐J model Hamiltonian and DFT calculations. In absence of an electric field the compound is paramagnetic, because the two electrons are localized on different parts of the POM. When an electric field is applied, an abrupt change of the magnetic coupling between the two delocalized electrons can be induced. Indeed, the field forces the two electrons to localize on nearest‐neighbors metal centers, leading to a very strong antiferromagnetic coupling. Both theoretical approaches have led to similar results, emphasizing that the sharp spin transition induced by the electric field in the V14 system is a robust phenomenon, intramolecular in nature, and barely influenced by small changes on the external structure. The influence of the electric field (E) on the direduced mixed‐valence polyoxometalate [GeV14O40]8−, which is paramagnetic at E=0, is studied. With the aid of DFT and a t‐J model Hamiltonian it is shown why and how the two “extra” electrons are suddenly coupled above a threshold voltage (see figure).