Systematic Study of a Family of Butterfly-Like {M₂Ln₂} Molecular Magnets (M = Mg^II, Mn^III, Co^II, Ni^II, and Cu^II; Ln = Y^III, Gd^III, Tb^III, Dy^III, Ho^III, and Er^III)

Abstract

A family of 3d-4f [M(II)2Ln(III)2(μ3-OH)2(O2C(t)Bu)10](2-) "butterflies" (where M(II) = Mg, Co, Ni, and Cu; Ln(III) = Y, Gd, Tb, Dy, Ho, and Er) and [Mn(III)2Ln(III)2(μ3-O)2(O2C(t)Bu)10](2-) molecules (where Ln(III) = Y, Gd, Tb, Dy, Ho, and Er) has been synthesized and characterized through single-crystal X-ray diffraction, SQUID magnetometry, and ab initio calculations. All dysprosium- and some erbium-containing tetramers showed frequency-dependent maxima in the out-of-phase component of the susceptibility associated with slow relaxation of magnetization, and hence, they are single-molecule magnets (SMMs). AC susceptibility measurements have shown that the SMM behavior is entirely intrinsic to the Dy and Er sites and the magnitude of the energy barrier is influenced by the interactions between the 4f and the 3d metal. A trend is observed between the strength of the 3d-4f exchange interaction between and the maximum observed in the χ″M(T).

Magnetic Nature of the CrIII–LnIII Interactions in [CrIII2LnIII3] Clusters with Slow Magnetic Relaxation

“…Among the many lanthanide‐based complexes, 3 d –4 f coordination clusters have been considered one of the most interesting molecular systems for magnetic studies . The strategy for constructing 3 d –4 f coordination clusters is to build metal cores with organic ligands, which act not only as bridging ligands to bridge 3 d and 4 f ions, but also as peripheral ligands to separate the discrete species from each other.…”

Fine Tuning of the Anisotropy Barrier by Ligand Substitution Observed in Linear {Dy2Ni2} Clusters

“…These critical geometrical parameters can direct the degree of communication between the 5 s , 5 p , and 5 d electrons of the Dy III ion and the 2 p electrons of the carboxylate O donors, to lead to slightly different intermetallic exchange interactions . The different exchange interactions between Dy III ⋅⋅⋅Ni II and Dy III ⋅⋅⋅Dy III in 1 – 3 can play a critical role in quenching QTM and thus favoring the observation of SMM behavior . Quite distinct from the consistently intermetallic ferromagnetic exchanges, the strength and even the type of the dipole–dipole interaction change significantly, especially between the two anisotropic Dy III ions.…”

Single-molecule magnet involving strong exchange coupling in terbium(iii) complex with 2,2′-bipyridin-6-yl tert-butyl nitroxide

“…16 It is known that he magnetization reversal is sensitive to the relaxations caused by the hyperfine couplings, 27 dipolar interactions in Ln ions, 28 and weak f-d and f-p exchange couplings. 29,30 It is noticed that the CSAPR principal axes of monoclinic Tb-6bpyNO are canted by 43° between neighbouring molecules. On the other hand, Tb2pyNO crystallizing in a triclinic P-1 space group 16 exhibits a cant angle of ca.…”