A Local D4h Symmetric Dysprosium(III) Single-Molecule Magnet with an Energy Barrier Exceeding 2000 K*.

Three six-coordinate DyIII single-molecule magnets (SMMs) [Dy(Ot Bu)2 (L)4 ]+ with local D4h symmetry are obtained by optimizing the equatorial ligands. One of the compounds with L=4-phenylpyridine shows an energy barrier (Ueff ) of 2075(11) K, which is the third largest Ueff , and the first Ueff >2000 K for SMMs with axial-type symmetry so far. Ab initio analysis indicates that the exceptional uniaxial magnetic anisotropy is deeply related to the axially compressed octahedral geometry. This work provides a new insight into the local D4h symmetry for high-performance SMMs.