Enhanced magnetic anisotropy in a tellurium-coordinated cobalt single-ion magnet

A series of tetrahedral Co(II) complexes with chalcogen donors were prepared, which exhibited strong magnetic uniaxial anisotropies and slow relaxations as SIMs. By substituting donors from S to Te, we realized the fine-tuning of the ligand field while keeping the coordination geometry virtually unchanged, yielding the first tellurium-coordinated SIM.