Soft magnetic hysteresis in a dysprosium amide-alkene complex up to 100 K

Lanthanides have recently shown magnetic memory at both the atomic and molecular level. The temperatures at which single-molecule magnets (SMMs) show magnetic hysteresis only increased from 4 K to 14 K in nearly 25 years since the discovery of the first SMM in 1993. However, since 2017 energy barriers to magnetic reversal (Ueff) from 1237 (28) -1631 (25) cm–1 and open magnetic hysteresis loops between 40-80 K have often been delivered by molecules featuring rigid aromatic ligands in axial dysprosium cyclopentadienyl complexes and their derivatives. Here we report a dysprosium bis (amide) -alkene complex, DyN (SiiPr3) [Si (iPr) 2C (CH3) =CHCH3N (SiiPr3) (SiiPr2Et) ]AlOC (CF3) 34 (1-Dy), which shows Ueff = 1843 (11) cm–1 and slow closing of magnetic hysteresis loops up to 100 K. Calculations show that the record Ueff value of 1-Dy arises from the charge-dense bis (silyl) amide ligands, with a pendant alkene taking a structural role to enforce a large N–Dy–N angle while imposing only a weak equatorial interaction. This leads to molecular spin dynamics up to one hundred times slower than the current best SMMs above 100 K.