Spectroscopic and Electrochemical Trends in Divalent Lanthanides through Modulation of Coordination Environment

Due to the importance of both visible-light luminescence and lanthanides in modern society, the influence of the ligand environment on complexes of Yb^II were studied and compared with analogous complexes of Eu^II. Four ligands with systematically varied electronic and steric characteristics were used to probe the coordination environment and electronic and redox properties of the corresponding Yb^II-containing complexes. Strong-field nitrogenous donors gave rise to bathochromic shifts, leading to visible-light absorption by Yb^II. Trends in properties across the series of Yb^II-containing complexes were compared to trends reported for the analogous Eu^II-containing complexes, revealing the translatability of coordination environment effects across the divalent lanthanide series. These studies provide valuable information regarding the behavior of small and medium-sized divalent lanthanides outside of the solid state.