A Trinuclear Radical‐Bridged Lanthanide Single‐Molecule Magnet

Abstract

Assembly of the triangular, organic radical-bridged complexes Cp* Ln (μ -HAN) (Cp*=pentamethylcyclopentadienyl; Ln=Gd, Tb, Dy; HAN=hexaazatrinaphthylene) proceeds through the reaction of Cp* Ln(BPh ) with HAN under strongly reducing conditions. Significantly, magnetic susceptibility measurements of these complexes support effective magnetic coupling of all three Ln centers through the HAN radical ligand. Thorough investigation of the Dy congener through both ac susceptibility and dc magnetic relaxation measurements reveals slow relaxation of the magnetization, with an effective thermal relaxation barrier of U =51 cm . Magnetic coupling in the Dy complex enables a large remnant magnetization at temperatures up to 3.0 K in the magnetic hysteresis measurements and hysteresis loops that are open at zero-field up to 3.5 K.

Strong direct exchange coupling and single-molecule magnetism in indigo-bridged lanthanide dimers

“…6 Thus, assuming that the easy axis of magnetization in 1 Dy and 2 Dy is oriented towards the [Cp*] -ligands, as has been determined through theoretical studies of many exemplar systems, 6,7 the hard oxygen and nitrogen donors can be regarded as residing in hard (equatorial) plane. As such, the diminished axiality of the Dy 3+ ion enables efficient relaxation via processes that shortcut the maximum possible thermal energy barrier, hence the low observed U eff values for these systems.…”

Theoretical Investigation of the Electronic Structure and Magnetic Properties of Oxo-Bridged Uranyl(V) Dinuclear and Trinuclear Complexes

“…This is difficult to achieve for 4f systems because they tend to form ionic bonds that limit magnetic exchange coupling and can only be successfully achieved via bridging radicals. [17][18][19][20][21] Consequently, since the discovery of the slow magnetic relaxation in the mononuclear complex U(Ph2BPz2)3, 22 an increasing number of studies have been directed to develop SMMs based on actinide-containing systems. [23][24][25][26][27][28] These studies include mono [29][30][31][32][33][34][35][36][37][38] and polynuclear systems [39][40][41] and heteropolymetallic uranium-3d metal complexes.…”

Magnetic Properties of LnIII–CuII 15‐Metallacrown‐5 Dimers with Terephthalate (LnIII = Pr, Nd, Sm, Eu)

“…Numerous studies of diverse lanthanide‐containing compounds have been provoked by their potential use in various catalytic processes, as MRI contrast agents, in sensors and optical materials, and in compounds with non‐trivial magnetic, and luminescence properties , . The significant magnetic anisotropy typical for Ln III ions in combination with their large ground state total spin can result in observation of SIM (single ion magnet), SMM (single molecule magnet) or SCM (single chain magnet) behavior in lanthanide‐containing discrete molecular complexes and coordination polymers , . Recently, multiple complexes with Ln III were reported to be able to demonstrate a considerable magnetocaloric effect, which has generated additional interest in this research area , …”