Assembling high-temperature single-molecule magnets with low-coordinate bis(amido) dysprosium unit [dyn2]+ via cl-k-cl linkage

Abstract

Symmetryandaxialityarethought tobeguides toward the pursuit of high energy barrier and blocking temperature for thedysprosium(III) (DyIII) single-molecule magnets (SMMs). The DyIII complexeswith low coordination numbers are intended to satisfy axial symmetry. Here, we report four four-coordinate DyIII SMMs based on bis(arylamido) dysprosium building block {Dy (NRR')2(μ-Cl)2K}(NRR'={N(SiMe3)(C6H3 iPr2-2,6)}-),with two strong Dy-N and twoweak Dy-Cl bonds. Through fine-tuning of axial anisotropy, the SMM with the largest N-Dy-N angle of 139.24(15)° displayed magnetic hysteresis with a coercive field (Hc) of 18.6 kOe at 2 K, which kept opening up to 35 K. Alternating current susceptibility measurement showed that the relaxation energy barrier reached as high as 1578 K, which is among the highest reported DyIII SMMs. Ab initio calculations revealed strong anisotropy and crystal-field axiality of the compound, despite the low symmetry, and provided a synthetically workable approach to construct high-performance SMMs useful in applications such as digital processing, transport electronics, quantumcomputing, and ultra-high-density data storage.