Dramatic Impact of Auxiliary Ligands on the Dynamic Magnetic Relaxation in Tetranuclear DyIII2ZnII2 Single Molecule Magnets.

Comprehensive Summary: Better understanding the determining factors of dynamic magnetic relaxation in polynuclear lanthanide based single‐molecule magnets (SMMs) remains a challenge due to the complexity of such architectures involving interactions between the magnetic centers. To address this issue, two structurally related heterometal DyIII2ZnII2 SMMs, [Zn2Dy2(L)4(Ac)2(DMF)(CH3OH)]·CH3OH·2H2O (1) and [Zn2Dy2(L)4(Ac)2(DMF)2]·4CH3CN (2) (H2L = (E)‐2‐((2‐hydroxy‐3‐methoxybenzylidene)amino)‐4‐methyphenol, DMF = N,N‐dimethylformamide), are introduced and investigated. Through modifying the auxiliary ligands on one DyIII site while retaining that on the other DyIII, the intramolecular magnetic interactions and relaxation dynamics in these two heterometallic‐DyIII2ZnII2 SMMs can be tuned, demonstrating a dramatic change in the magnet relaxation behavior with energy barrier changing from a negligible value for 1 to 305 K for 2. Ab initio calculations reveal that changing the coordination geometries on the DyIII sites can significantly affect the magnetic interactions as well as single‐ion anisotropy. [ABSTRACT FROM AUTHOR]