Benner Florian, Pugliese Elizabeth R, Castellanos Ernesto, Deshapriya Saroshan, Demir Selvan
Department of Chemistry, Michigan State University, 578 South Shaw Lane, East Lansing, Michigan 48824, United States.
Inorg Chem. 2025 Jun 2;64(21):10359-10368. doi: 10.1021/acs.inorgchem.4c05349. Epub 2025 May 20.
Neutral organometallic complexes containing a formally divalent terbium ion are especially scarce, owing to the highly negative Tb/Tb reduction potential and the thermodynamic stability of the Tb ion. In fact, there are only two crystallographically characterized neutral terbium(II) complexes known to date. Here, we present the synthesis of the unprecedented heteroleptic Tb(III) bis(amide) chloride complex, (NHAr*)TbCl () (where Ar* = 2,6-(Ar')CH, Ar' = 2,4,6-(Pr)CH), which was chemically reduced using the strong reducing agent, KC, to yield a new member of this small family of highly reactive Tb compounds, namely, the homoleptic terbium bis(amide) complex, (NHAr*)Tb (). Notably, the spectroscopic and magnetic characterization of revealed that the compound contains a formally divalent terbium ion since the additional electron was exclusively found to reside in the primarily arene ligand-based π* orbitals, as corroborated by calculations. Furthermore, exhibits slow magnetic relaxation between 1.8 and 16 K under a 1250 Oe applied dc field. calculations uncovered that magnetic relaxation occurs through the first excited spin-orbit state. Study of via SQUID magnetometry hints at considerably weaker 4f-5d magnetic coupling relative to other Tb complexes, rendering its electronic structure unique relative to that of other neutral organometallic Tb complexes.
由于铽离子具有高度负的Tb/Tb还原电位和热力学稳定性，含有形式上二价铽离子的中性有机金属配合物特别稀少。事实上，迄今为止已知的只有两种经晶体学表征的中性铽（II）配合物。在此，我们展示了前所未有的杂配体Tb(III)双（酰胺）氯化物配合物(NHAr*)TbCl（其中Ar* = 2,6-(Ar')CH，Ar' = 2,4,6-(Pr)CH）的合成，该配合物使用强还原剂KC进行化学还原，以产生这个高反应活性铽化合物小家族的一个新成员，即同配体铽双（酰胺）配合物(NHAr*)₂Tb。值得注意的是，对[（NHAr*）₂Tb]的光谱和磁性表征表明，该化合物含有一个形式上的二价铽离子，因为额外的电子被专门发现存在于主要基于芳烃配体的π轨道中，这一点得到了计算的证实。此外，[（NHAr）₂Tb]在1250 Oe的外加直流磁场下，在1.8至16 K之间表现出缓慢的磁弛豫。计算发现磁弛豫通过第一激发自旋轨道态发生。通过超导量子干涉仪磁强计对[（NHAr*）₂Tb]的研究表明，相对于其他铽配合物，其4f - 5d磁耦合相当弱，使其电子结构相对于其他中性有机金属铽配合物而言具有独特性。
