Two C2v Symmetry Dysprosium(III) Single-Molecule Magnets with Effective Energy Barriers over 600 K

Two mononuclear DyIII single-molecule magnets (SMMs) with C2v coordination symmetry were synthesized. Both of them have strong uniaxial magnetic anisotropy with high effective energy barriers for magnetization reversal over 600 K and hysteresis loops opened up to 8 K, and they are by far the best lanthanide SMMs with a C2v symmetry coordination environment. Ab initio calculations reveal that the crystal field around the DyIII ion is the key factor determining the magnetization dynamics of the SMMs. The multidentate ligand controls the orientation of the main magnetic axes which are both nearly parallel to the phenoxide Dy–O bonds and perpendicular to the equatorial plane with relatively weak coordination by the four nitrogen atoms and one Cl− or Br− anion. The variation of the terminal Cl− or Br− anion slightly influences the magnetization dynamics. This work provides the fundamentals to govern the SMM behavior of lanthanide complexes with a relatively low coordination symmetry of the lanthanide center.