An Anomalous Electron Configuration Among 3<i>d</i> Transition Metal Atoms

Abstract Physical properties of materials are mainly determined by valence electron configurations, where different valence shells would induce divergent phenomena. In compounds containing Sc 2+ , 3 d electron occupancy is expected, the same as other transition metal atoms like Ti 3+ . But this situation still awaits experimental verification in inorganic materials. Here, we selected ScS to measure the valence electron density and orbital population of Sc 2+ through delicate quantitative convergent‐beam electron diffraction. With the absence of 3 d orbital features around Sc‐atom sites and the nearly bare population of t 2g orbital, the unintuitive occupation of 4 s orbital in Sc 2+ is concluded. It should be the first time to report such a special electron configuration in a transition metal compound, in which 4 s rather than 3 d orbital is preferred. Our findings reveal the distinct behavior of Sc and probable ways to modulate material properties by controlling electron orbitals.