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Abstract：
Synthesis of molecular compounds with metal-metal bonds between 4f elements is recognized as one of the fascinating milestones in lanthanide metallochemistry. The main focus of such studies is on heavy lanthanides due to the interest in their magnetism, while bonding between light lanthanides remains unexplored. In this work, the Nd─Nd bonding in Nd-dimetallofullerenes as a case study of metal-metal bonding between early lanthanides is demonstrated. Combined experimental and computational study proves that pristine Nd2 @C80 has an open shell structure with a single electron occupying the Nd─Nd bonding orbital. Nd2 @C80 is stabilized by a one-electron reduction and further by the electrophilic CF3 addition to [Nd2 @C80 ]- . Single-crystal X-ray diffraction reveals the formation of two Nd2 @C80 (CF3 ) isomers with D5h -C80 and Ih -C80 carbon cages, both featuring a single-electron Nd─Nd bond with the length of 3.78-3.79 Å. The mutual influence of the exohedral CF3 group and endohedral metal dimer in determining the molecular structure of the adducts is analyzed. Unlike Tb or Dy analogs, which are strong single-molecule magnets with high blocking temperature of magnetization, the slow relaxation of magnetization in Nd2 @Ih -C80 (CF3 ) is detectable via out-of-phase magnetic susceptibility only below 3 K and in the presence of magnetic field.
摘要：
在4f元素之间具有金属-金属键的分子化合物的合成被认为是镧系元素金属化学中令人着迷的里程碑之一。由于对其磁性的兴趣，此类研究的主要重点是重镧系元素，而轻镧系元素之间的结合仍未探索。在这项工作中,作为早期镧系元素之间金属-金属键合的案例研究，证明了Nd-二金属富勒烯中的Nd-Nd键。结合实验和计算研究证明，原始Nd2@C80具有开放的壳结构，单电子占据Nd─Nd键合轨道。Nd2@C80通过单电子还原并进一步通过向[Nd2@C80]-添加亲电子CF3来稳定。单晶X射线衍射揭示了具有D5h-C80和Ih-C80碳笼的两种Nd2@C80（CF3）异构体的形成，均具有单电子Nd-Nd键，长度为3.78-3.79µ。分析了外面体CF3基团和内面体金属二聚体在确定加合物分子结构中的相互影响。与Tb或Dy类似物不同，是强单分子磁体，具有高磁化阻挡温度，Nd2@Ih-C80（CF3）中磁化的缓慢弛豫仅在3K以下且存在磁场的情况下通过异相磁化率即可检测到。
