Uncovering the 3d and 4d Electronic Interactions in Solvated Ru Complexes with 2p3d Resonant Inelastic X-ray Scattering

We examined a variety of solution phaseRu complexes withvarying oxidation states and ligand identities with L-3-edge2p3d resonant inelastic X-ray scattering (RIXS). This technique providesinsight into the unoccupied 4d valence orbitals, the occupied 3d orbitals,and the electronic interactions within and between these levels. Ofparticular note is that this technique allows for the direct measurementof 3d spin orbit coupling which splits the 3d(5/2) and 3d(3/2) orbitals. Theelectronic structure and dynamics of ruthenium complexesarewidely studied given their use in catalytic and light-harvesting materials.Here we investigate three model Ru complexes, [Ru-III(NH3)(6)](3+), [Ru-II(bpy)(3)](2+), and [Ru-II(CN)(6)](4-), with L-3-edge 2p3d resonant inelastic X-ray scattering(RIXS) to probe unoccupied 4d valence orbitals and occupied 3d orbitalsand to gain insight into the interactions between these levels. The2p3d RIXS maps contain a higher level of spectral information thanthe L-3 X-ray absorption near edge structure (XANES). Thisstudy provides a direct measure of the 3d spin-orbit splittingsof 4.3, 4.0, and 4.1 eV between the 3d(5/2) and 3d(3/2) orbitals of the [Ru-III(NH3)(6)](3+), [Ru-II(bpy)(3)](2+), and [Ru-II(CN)(6)](4-) complexes, respectively.

Automated summary

Using L-3-edge 2p3d resonant inelastic X-ray scattering (RIXS), we investigated the electronic structure and dynamics of different solution phase Ru complexes, providing insights into the 4d and 3d orbitals and their interactions. This technique allows for direct measurement of 3d spin orbit coupling and splitting of orbitals. The study examined three model Ru complexes and demonstrated the higher spectral information provided by 2p3d RIXS compared to L-3 X-ray absorption near edge structure (XANES). The direct measurement of spin-orbit splitting was carried out for the studied complexes.