Dysprosiacarboranes: A New Type of Organometallic Single-Molecule Magnets
Dicarbollide ion, nido-C<sub>2</sub>B<sub>9</sub>H<sub>11</sub><sup>2-</sup> is isoelectronic with cyclopentadienyl. Here we make dysprosiacarboranes, namely [(C<sub>2</sub>B<sub>9</sub>H<sub>11</sub>)<sub>2</sub>Ln(THF)<sub>2</sub>][Na(THF)<sub>5</sub>] (Ln = Dy, <b>1Dy</b>) and [(THF)<sub>3</sub>(μ-H)<sub>3</sub>Li]<sub>2</sub>[{η<sup>5</sup>-C<sub>6</sub>H<sub>4</sub>(CH<sub>2</sub>)<sub>2</sub>C<sub>2</sub>B<sub>9</sub>H<sub>9</sub>}Dy{η<sup>2</sup>:η<sup>5</sup>-C<sub>6</sub>H<sub>4</sub>(CH<sub>2</sub>)<sub>2</sub>C<sub>2</sub>B<sub>9</sub>H<sub>9</sub>}<sub>2</sub>Li] <b>3</b> and show that dicarbollide ligands impose strong magnetic axiality on the central Dy(III) ion. The effective energy barrier (Ueff) for loss of magnetisation can be varied by the substitution pattern on the dicarbollide. This is demonstrated by comparing complexes of nido-C<sub>2</sub>B<sub>9</sub>H<sub>11</sub><sup>2-</sup> and nido-[o-xylylene-C<sub>2</sub>B<sub>9</sub>H<sub>9</sub>]<sup>2-</sup> which show Ueff of 430(5) K and 804(7) K, respectively. The blocking temperature defined by the open hysteresis temperature of 3 reaches 6.8 K. Moreover, the linear complex [Dy(C<sub>2</sub>B<sub>9</sub>H<sub>11</sub>)<sub>2</sub>]<sup>-</sup> is predicted to have comparable SMM properties with linear [Dy(CpMe<sub>3</sub>)<sub>2</sub>]<sup>+</sup> complex. As such, carboranyl ligands and its derivatives may open a new type of organometallic ligands for high-performance SMM design. <br>