Lanthanide and Actinide Electronic Structure Explored Through Soft X-Ray Spectromicroscopy of Ln/An-2,2':6,2'-terpyridine Coordination Compounds.

The role f-electrons play in coordination and bonding has been a central focus of research in the lanthanides and actinides for decades, with particular relevance to applications in lanthanide-actinide separations. An intriguing ligand for studying lanthanide and actinide bonding is 2,2’:6,2’-terpyridine (terpy) because the nitrogens in terpy could potentially act as soft electron donors, with differences in bonding between the ligand and a central actinide compared to a central lanthanide. Furthermore, changes in the metal ionic radius can affect how the ligand coordinates with the central f-element atom. Soft x-ray absorption spectroscopy measurements have been performed on lanthanide-terpy complexes (Ln = Ce, Pr, Nd, Sm, Gd, Dy, Ho, Er) at the nitrogen K-edge and lanthanide M_4,5-edges. Results are complemented with Results indicate a clear difference in electronic structure between the lighter and heavier lanthanides. X-ray emission spectroscopy studies following the initial x-ray absorption measurements conducted by STXM are also shown. These experiments were performed at the Advanced Light Source scanning transmission x-ray microscopes at Beamline 11.0.2 and 4.0.3. Interpretation of these results, including theoretical calculations, along with ongoing efforts to extend this system to actinide-terpy compounds will be presented.