Dysprosiacarboranes as Organometallic Single-Molecule Magnets.

Abstract

The dicarbollide ion, nido-C2 B9 H11 2- is isoelectronic with cyclopentadienyl. Herein, we make dysprosiacarboranes, namely [(C2 B9 H11 )2 Ln(THF)2 ][Na(THF)5 ] (Ln=Dy, 1Dy) and [(THF)3 (μ-H)3 Li]2 [{η5 -C6 H4 (CH2 )2 C2 B9 H9 }Dy{η2 :η5 -C6 H4 (CH2 )2 C2 B9 H9 }2 Li] 3Dy and show that dicarbollide ligands impose strong magnetic axiality on the central DyIII ion. The effective energy barrier (Ueff ) for the loss of magnetization can be varied by the substitution pattern on the dicarbollide. This finding is demonstrated by comparing complexes of nido-C2 B9 H11 2- and nido-[o-xylylene-C2 B9 H9 ]2- , which show a Ueff of 430(5) K and 804(7) K, respectively. The blocking temperature defined by the open hysteresis temperature of 3Dy reaches 6.8 K. Moreover, the linear complex [Dy(C2 B9 H11 )2 ]- is predicted to have comparable properties with the linear [Dy(CpMe3 )2 ]+ complex. As such, carboranyl ligands and their derivatives may provide a new type of organometallic ligand for high-performance single-molecule magnets.