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Abstraction of a chloride ligand from the dysprosium metallocene [(Cpttt)2DyCl] ( 1Dy Cpttt=1,2,4-tri( tert-butyl)cyclopentadienide) by the triethylsilylium cation produces the first base-free rare-earth metallocenium cation [(Cpttt)2Dy]+ ( 2Dy) as a salt of the non-coordinating [B(C6F5)4]− anion. Magnetic measurements reveal that [ 2Dy][B(C6F5)4] is an SMM with a record anisotropy barrier up to 1277 cm−1 (1837 K) in zero field and a record magnetic blocking temperature of 60 K, including hysteresis with coercivity. The exceptional magnetic axiality of 2Dy is further highlighted by computational studies, which reveal this system to be the first lanthanide SMM in which all low-lying Kramers doublets correspond to a well-defined MJ value, with no significant mixing even in the higher doublets. [ABSTRACT FROM AUTHOR]

Two dysprosium complexes, [(C5H4Me)2Dy(L1)] (3) and [(L1)Dy(μ-Cl)3{Li(tmeda)}]2 (4), with amino-functionalized pentadienyl ligands L1 are described. Crystallographic studies of 3 and 4 show that the pendant amino group influences the pentadienyl conformation and the ligand hapticity. Electronic structure calculations reveal that L1 has a strong influence on the orientation of the main magnetic axis of the ground Kramers doublets in 3 and 4. [ABSTRACT FROM AUTHOR]