Divalent manganese (Mn2+, 3d5) charge transfer energies and vacuum-referred binding energies in inorganic compounds

Ongoing efforts to develop a predictive model governing the host-referred binding energies (HRBEs) and vacuum-referred binding energies (VRBEs) of transition metal dopants in inorganic host compounds are stymied by a lack of cross-compound data sets that capture transitions between the dopant ions and the valence and conduction bands of the hosts. Herein, we have compiled data consistent with Mn²⁺ charge transfer processes in 53 different compounds, spanning fluorides, oxides, chlorides, bromides, and nitrides. By assigning these transitions to Mn²⁺ → conduction band metal-to-metal charge transfer and combining these energies with the binding energies of electrons in the valence and conduction bands of the various hosts, we have calculated the HRBEs and VRBEs of the Mn²⁺ ion across a range of compounds. We show that variations in the Mn²⁺ VRBE are small relative to the variations in the VRBE of the valence and conduction bands, which manifests an approximately linear relationship between the Mn²⁺ HRBE and the bandgap energy of host compounds. We investigated the relationship between the Mn²⁺ VRBE and the various structures of the host compounds and showed that the chemical shift experienced by the Mn²⁺ ion depends on the electronegativity of the ligand, the Mn²⁺ coordination, and the Mn-ligand bond lengths in a predictable manner.