[OsF₆]^<i>x</i>−: Molecular Models for Spin‐Orbit Entangled Phenomena

Heavy 5d elements, like osmium, feature strong spin‐orbit interactions which are at the origin of exotic physical behaviors. Revealing the full potential of, for example, novel osmium oxide materials (“osmates”) is however contingent upon a detailed understanding of the local single‐ion properties. Herein, two molecular osmate analogues, [OsF 6 ] 2− and [OsF 6 ] − , are reported as model systems for Os 4+ and Os 5+ centers found in oxides. Using X‐ray absorption spectroscopy (XAS) and X‐ray magnetic circular dichroism (XMCD) techniques, combined with state‐of‐the‐art ab initio calculations, their ground state was elucidated; mirroring the osmium electronic structure in osmates. The realization of such molecular model systems provides a unique chemical playground to engineer materials exhibiting spin‐orbit entangled phenomena.