Single-molecule magnets (SMMs) are molecules that can retain magnetic polarization in the absence of an external magnetic field and embody the ultimate size limit for spin-based information storage and processing. Multimetallic lanthanide complexes lacking magnetic exchange coupling enable fast relaxation pathways that attenuate the full potential of these species. Employment of diamagnetic heavy main group elements with diffuse orbitals may lead to unprecedented strong coupling. Herein, two bismuth-cluster-bridged lanthanide complexes, [K(THF)₄]₂[Cp∗₂Ln₂Bi₆] (Cp∗ = pentamethylcyclopentadienyl; 1-Ln, Ln = Tb, Dy), were synthesized via a solution organometallic approach. The neutral [Ln₂Bi₆] heterometallocubane core features lanthanide centers that are bridged by a rare Bi₆⁶⁻ Zintl ion, which supports strong ferromagnetic interactions between lanthanides. This affords the rare observation of magnetic blocking and open hysteresis loops for superexchange-coupled SMMs comprising solely lanthanide ions. Both compounds constitute the first SMMs containing bismuth donors paving the way for promising synthetic targets for quantum computation.

单分子磁体 (SMM) 是在没有外部磁场的情况下可以保持磁极化的分子，体现了基于自旋的信息存储和处理的最终尺寸限制。缺乏磁交换耦合的多金属镧系元素配合物可实现快速弛豫途径，从而削弱这些物种的全部潜力。使用具有扩散轨道的抗磁性重主族元素可能会导致前所未有的强耦合。这里，两个铋簇桥连的镧系元素配合物，[K(THF) ₄ ] ₂ [Cp∗ ₂ Ln ₂ Bi ₆ ] (Cp∗ = 五甲基环戊二烯基；1-Ln, Ln = Tb, Dy)，通过溶液有机金属方法合成。中性 [Ln ₂ Bi ₆ ] 异金属立方烷核心具有镧系元素中心，由稀有的 Bi ₆ ^6- Zintl 离子桥接，支持镧系元素之间的强铁磁相互作用。这为仅包含镧系元素离子的超交换耦合 SMM 提供了罕见的磁阻塞和开磁滞回线观察。这两种化合物构成了第一个含有铋供体的 SMM，为有希望的量子计算合成目标铺平了道路。