Engineering a high-barrier d-f single-molecule magnet centered with hexagonal bipyramidal Dy(III) unit

In the pursuit of high-performance single-molecule magnets (SMMs), incorporating intramolecular magnetic coupling emerges as a pivotal strategy. Among these, d-f SMMs have garnered significant attention due to their remarkable versatility, which lies in their ability to tune coordination environments and facilely substitute metal centers. However, achieving performance-centric d-f SMMs through the synergistic interplay between highly anisotropic f ions and d-f magnetic interactions remains a formidable challenge. While mononuclear hexagonal bipyramidal (D_6h) Dy^III SMMs have been successfully isolated, the exploration of d-f SMMs featuring D_6h-lanthanide metal centers remains uncharted territory. In this study, we employed planar bipodal ligands in conjunction with “staple-like” axial phenoxide ligands to synthesize the first hexagonal bipyramidal d-f SMM. Remarkably, this compound exhibits alternating-current magnetic susceptibilities peaking up to 68 K with an energy barrier surpassing 1,200 K, thus establishing a new benchmark within the heterometallic d-f SMM landscape inclusive of complexes with diamagnetic d metals and paramagnetic f ions. Notably, the ferromagnetic interaction at the d-f sites engenders oscillating relaxation times contingent on the magnetic field — a characteristic distinct from mononuclear SMMs. These findings shed light on a deliberate design approach for d-f SMMs, emphasizing the cooperative utilization of high-barrier lanthanide modules alongside d ions through magnetic interactions. This synergy significantly enhances and diversifies the magnetic dynamics of these intriguing molecular systems.