Borolide Sandwich Complex as a High-Performance Single-Molecule Magnet

Borolide Sandwich Complex as a High-Performance Single-Molecule Magnet

Author: ChemistryViews

Single-molecule magnets (SMMs) could be useful, e.g., for high-density data storage or next-generation technologies such as quantum computers. Lanthanide-based SMMs—in particular, double-decker complexes—are promising and can provide large energy barriers for the relaxation of magnetization. Lanthanide-based SMMs with Ln3+ ions are particularly interesting because Ln3+ ions have intrinsically strong anisotropic electron densities. They can be further tuned by choosing an appropriate ligand field.

Michael Nippe, Texas A&M University, College Station, USA, and colleagues have synthesized an aminoborolide ligand and used it to build an SMM, i.e., an anionic homoleptic Dy3+ sandwich complex (pictured). The team first synthesized 1-piperidino-2,3,4,5-tetraphenylborole via a reaction of piperidino(dichloro)borane with dilithiotetraphenylbutadienide. This borole was then reduced with potassium graphite (KC8) to give [K(THF)]2[1-(piperidino)-2,3,4,5-tetraphenylborolide], which contains the desired anionic ligand. A salt metathesis reaction was then used to prepare the complex [K(THF)6][1-(piperidino)-2,3,4,5-tetraphenylborolyl]2Dy, and [2.2.2]-cryptand was added to obtain the more stable [K(2.2.2)][1-(piperidino)-2,3,4,5-tetraphenylborolyl]2Dy as a single-molecule magnet.

The dianionic borolide ligands exert strong ligand fields on the trivalent lanthanide ion, resulting in high magnetic anisotropy. The SMM has a high blocking temperature (the temperature below which a material shows slow relaxation of magnetization) of 66 K and a comparatively large barrier for the reversal of magnetization. With these properties, the complex is among the best-performing SMMs reported so far, according to the researchers.


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