Significant Control on Zero‐Field Quantum Tunneling of Magnetization in Dysprosium Based Single‐Molecule Magnets via Orientation of the Anilato Ligand

Tuning the bridging fashion of anilato ligand in dinuclear DyIII complexes, reveals a sizable effect on the slow relaxation of magnetization. Combined experimental and theoretical studies divulge that the geometry with high order axial symmetry (pseudo square antiprism) reduces the transverse crystal fields corresponding to QTM (quantum tunneling of magnetization) resulting in a significant increase in energy barrier (Ueff=518 cm−1) through the Orbach relaxation process whereas the geometry with lower symmetry (triangular dodecahedron, pseudo D2d) enhances the transverse crystal fields that accelerate the ground state QTM process. Notably, the value 518 cm−1 represents the highest energy barrier among anilato ligand based SMMs. The bridging ligand orientation in a dinuclear Dy(III) complex provides different coordination geometry. The geometry with higher axial symmetry (pseudo square antiprism) around DyIII centre gives higher energy barrier (Ueff) than the low order symmetric geometry [triangular dodecahedron geometry (pseudo D2d)] due to the large difference in their transverse anisotropy.