Predicting Magnetic Barriers in Lanthanide Complexes with Electrostatic Potential Charges

Single-molecule magnets (SMMs) with slow relaxation of magnetization and blocking temperatures above that of liquid nitrogen are essential for practical applications in high-density data storage devices and quantum computers. A rapid and accurate prediction of the effective magnetic relaxation barrier (<i>U</i>_eff) is needed to accelerate the discovery of high-performance SMMs. Using density functional theory and multireference calculations, we explored correlations between <i>U</i>_eff, partial atomic charges, and the anisotropic barrier for a series of sandwich-type lanthanide complexes containing cyclooctatetraene, substituted cyclopentadiene, phospholyl, boratabenzene, or borane ligands. Our results show a correlation between the electrostatic potential charge of the lanthanide ion in the complex and <i>U</i>_eff. Systematic ligand modifications show that reducing ligand nucleophilicity and incorporating soft bases enhance magnetic anisotropy and <i>U</i>_eff values. This work identifies a correlation to predict <i>U</i>_eff values and optimization of ligand coordination environments in lanthanide-based SMMs.