Tetraanionic Biphenyl Lanthanide Complexes as Single-Molecule Magnets
摘要:
Inverse sandwich biphenyl complexes [(NNTBS)Ln](2)(mu-biphenyl)[K(solvent)](2) [NNTBS = 1,1'-fc(NSitBuMe(2))(2); Ln = Gd, Dy, Er; solvent = Et2O, toluene; 18-crown-6], containing a quadruply reduced biphenyl ligand, were synthesized and their magnetic properties measured. One of the dysprosium biphenyl complexes was found to exhibit antiferromagnetic coupling and single-molecule-magnet behavior with U-eff of 34 K under zero applied field. The solvent coordinated to potassium affected drastically the nature of the magnetic interaction, with the other dysprosium complex showing ferromagnetic coupling. Ab initio calculations were performed to understand the nature of magnetic coupling between the two lanthanide ions bridged by the anionic arene ligand and the origin of single-molecule-magnet behavior.
与顺磁性镧系元素(Sc,Y,La和Lu)相比,顺磁性镧系元素(Ln,从Ce到Yb)的有机金属化学远没有那么发达。缺乏可用的起始原料和表征方法是主要障碍。本文中我们报道了钕,g 、,和的三苄基配合物的合成和表征。此外,我们介绍了一种直接程序,用于从相应的氧化物开始合成由二茂铁二酰胺配体支撑的镧系元素苄基和碘化物配合物。所有新合成的化合物均通过X射线晶体学,1 H NMR光谱((化合物为NMR静音)和元素分析进行了表征。