Exchange-driven slow relaxation of magnetization in NiII2LnIII2 (Ln^III = Y, Gd, Tb and Dy) butterfly complexes: experimental and theoretical studies

Abstract

The tetranuclear NiII2LnIII2 complexes, [{L′2{Ni(MeOH)(μ-OAc)}2(μ3-MeO)2Ln2}; LnIII = YIII (1), GdIII (2), TbIII (3), DyIII (4)] were prepared using a Schiff base ligand, H3L [H3L = 3-((2-hydroxy-3-methoxybenzylidene)amino)-2-(2-hydroxy-3-methoxyphenyl)-2,3-dihydroquinazolin-4(1H)-one, whereas {L′}3- is the...

Tuning Quantum Tunneling in Isomorphic {MII2DyIII2} “Butterfly” System via 3d-4f Magnetic Interaction

“…Therefore, suppressing the QTM effect is still a current challenge for chemists that needs to be explored. The previous experimental and theoretical studies have confirmed that introducing strong spin–spin exchange coupling between metal ions and defining high-crystal field symmetry around individual lanthanide ions are two main strategies to suppress the QTM effect. − In view of the above considerations, various 3d-4f heterometallic complexes with strong magnetic interactions existing in the heterometallic clusters are constructed, in which the metal ions are bridged by monatomic oxygen. − Meanwhile, a more efficient exchange coupling can also be obtained through optimizing the crystal field of Dy III ions by selecting transition metal ions reasonably . As expected, the studies of butterfly type [Co II 2 Dy III 2 ] by Powell and Song suggest the magnetic coupling between 3d and 4f ions can significantly reduce the QTM effect. , However, there are only a few examples reported so far.…”

Lanthanoid coordination prompts unusually distorted pseudo-octahedral NiII coordination in heterodinuclear Ni–Ln complexes: synthesis, structure and understanding of magnetic behaviour through experiment and computation

“…30,31 Apart from that, the Ni II centre often exhibits ferromagnetic exchange coupling with 4f metal ions. [32][33][34][35][36][37] Hence, the new family of SMMs possessing large effective energy barriers for the reversal of magnetization (U eff ), and hence higher blocking temperatures (T B ), can be constructed by putting highly anisotropic trivalent 4f and bivalent Ni ions in close proximity. The higher coordination requirement around the Ln III ions following ligand chelation is achieved by inorganic anions like NO 3 − , RCO 2 − etc.…”

Understanding electrostatics and covalency effects in highly anisotropic organometallic sandwich dysprosium complexes [Dy(CmRm)2] (where R = H, SiH3, CH3 and m = 4 to 9): a computational perspective

“…55 In this context, computational tools in the density functional theory (DFT) and post-Hartree-Fock-based CASSCF/CASPT2 methods have played a profound role in correlating the electronic structure and magnetic anisotropy of lanthanide-based molecular magnets. 25,27,35,38,45,52,[56][57][58][59][60][61] Several attempts have been made to investigate the covalency effects by substituting ligands with formal charges or using more complex effective charge models to understand how covalency influences the magnetic anisotropy of Ln(III) ions. 51,52,[61][62][63][64] In one of the seminal works, Ungur et al have rigorously discussed ab initio crystal field and atomic point charge crystal field model approaches to study the crystal field effects in lanthanide complexes.…”