A Dysprosium Metallocene Single‐Molecule Magnet Functioning at the Axial Limit

Abstract

Abstraction of a chloride ligand from the dysprosium metallocene [(Cpttt)2DyCl] (1Dy Cpttt=1,2,4‐tri(tert‐butyl)cyclopentadienide) by the triethylsilylium cation produces the first base‐free rare‐earth metallocenium cation [(Cpttt)2Dy]+ (2Dy) as a salt of the non‐coordinating [B(C6F5)4]− anion. Magnetic measurements reveal that [2Dy][B(C6F5)4] is an SMM with a record anisotropy barrier up to 1277 cm−1 (1837 K) in zero field and a record magnetic blocking temperature of 60 K, including hysteresis with coercivity. The exceptional magnetic axiality of 2Dy is further highlighted by computational studies, which reveal this system to be the first lanthanide SMM in which all low‐lying Kramers doublets correspond to a well‐defined MJ value, with no significant mixing even in the higher doublets.

Giant coercivity and high magnetic blocking temperatures for N2 3− radical-bridged dilanthanide complexes upon ligand dissociation

“…The use of selected 4f metal ions, particularly Tb III , Dy III , and Er III , has recently dominated this area of research due to the advantageous combination of high magnetic moment and intrinsic magnetic anisotropy engendered by large spin–orbit coupling 4–11 . Progress in increasing blocking temperatures and coercive fields has been challenging mainly owing to the prevalence of through-barrier relaxation pathways, such as quantum tunneling of the magnetization, though recent reports on a molecule containing a single Dy III ion demonstrate Orbach relaxation proceeding through nearly the entire effective magnetization reversal barrier ( U eff ) of greater than 1200 cm −1 , with a correspondingly high 100-s blocking temperature 12, 13 .…”

“…One strategy for suppressing quantum tunneling of the magnetization is to establish rigorously symmetry-protected pure M J states 15 , a condition as-yet only experimentally achieved in adatom-surface experiments 16 , though reports of the high-blocking temperature [Dy(Cp ttt ) 2 ] + (Cp ttt  = 1,2,4-tri( tert -butyl)cyclopentadienide) complex suggest that rigorous symmetry may not be crucial to achieve high performance in single-ion magnetic molecules 12, 13 . Another promising route is the design of systems with strong intramolecular magnetic coupling between two or more metal centers.…”

Magnetic properties of single rare-earth atoms on graphene/Ir(111)

“…Rare-earth (RE) atoms possess an intrinsic large spinorbit interaction and their magnetic states are well decoupled from the environment. These properties have been exploited to design single ion molecular magnets with magnetic bistability on a long timescale [12][13][14][15][16]. Magnetic remanence and long magnetic lifetimes have also been achieved in single RE adatoms.…”

The modular synthesis of rare earth-transition metal heterobimetallic complexes utilizing a redox-active ligand

“…5 The very recent reports of magnetic hysteresis at 60 K in a dysprosocenium cation are a testament to the power of the organometallic molecular design approach. 6,7 Our aim was to identify and use a redox-active bridging ligand with multiple and selective binding sites as the template for a general and modular synthetic route to heterometallic d-f or f-f′ complexes. The ligand used in this work 1,10-phenathroline-5,6-dione ( pd) has been predominantly studied for its physical organic, biological and bio-inorganic chemistry, particularly as a precursor to DNA intercalation agents and photocatalysts.…”