Field-induced Slow Magnetic Relaxation in Tetrahedral Cobalt(II)Complexes with Halide Donors

摘要

Single-molecule magnets with a single magnetic center are called single-ion magnets(SIMs).Numerous 3d metal complexes have been reported since the first discovery.Among3d metal-based SIMs,particular attention have been devoted to the tetrahedral cobalt(II)complexes because of the enhanced magnetic anisotropy.However,most 3d SIMs does notexhibit slow relaxation of magnetization in the absence of a dc field due to fast magneticrelaxation through quantum tunneling (QTM).As dipolar interactions induce the QTM,SIMs are designed to be discrete and separated in the crystal.On the other hand,we recentlyreported two bis-bidentate cobalt(II) SIMs with supramolecular 1-D chain structure byintermolecular hydrogen-bonds,in which intrachain Co···Co distances are 6.0-6.4 A.Owing to the weak intermolecular magnetic coupling,which splits the ground ±Ms levels,these compounds exhibited slow magnetic relaxation in the absence of a dc field.1 Tounderstand the correlation between the intermolecular Co···Co distance and relaxationdynamics in detail,we focused on a series of tetrahedral cobalt(II) complexes with 1-Dchain structure containing halide donor as hydrogen-bond acceptor.