Single-Molecule Magnet Behavior in Dy³⁺ Half-Sandwich Complexes Based on Ene-Diamido and Cp* Ligands

Abstract

We report in this communication the synthesis, structure and magnetic investigations of two new half-sandwich complexes [Dy(DAD)Cp*(THF)] (1) and [Li(THF) 3 ][Dy(DAD)Cp*Cl] (2) (Cp* = C 5 Me 5 , DAD = [2,6-iPr 2 C 6 H 3 N-CMeCMe-NC 6 H 3 iPr2-2,6). Both compounds exhibit zero-field SMM behavior but distinct relaxation dynamics originating from difference in the arrangement of Cp* and DAD ligands. The anisotropic barrier for 1 is found one order of magnitude greater than for 2.

Single-molecule magnet behavior in heterolopetic Dy3+-chloro-diazabutadiene complexes: influence of the nuclearity and ligand redox state

“…Although not directly comparable, we previously observed such broad signals in dysprosium heteroleptic and homoleptic complexes based on the same DAD 2Me ligand. [53][54] We also note that for 1, the relaxation dynamics is most likely dominated by a Raman process as we recently evidenced recently on homoleptic complexes based on DAD ligands. 52, 54 Unfortunately, it turns out that connecting the Dy 3+ ions through chloro-bridges does not rigidify the structure to prevent the Raman relaxation.…”

“…) for designing homo or heteroleptic lanthanide based SMMs. [51][52][53][54] Such ligands are interesting candidates for the synthesis of new SMMs because: (i) they could act both, as  (N atoms) and  (CC bond) electron donors, (ii) they usually present a dianionic character when coordinated to Ln 3+ ions, (iii) their great steric tunability through modification of the substituent groups may be viewed as an important advantage to finely tune the coordination environment, (iv) the Dy-N distances were found relatively short, that gives rise to a relatively large crystal-field splitting and the appearance of a genuine SMM behaviour. 52 Another interesting feature of diazabutadiene system consists also in the presence of several redox states including a radical-anionic one, which may be attractive to provide strong exchange interactions with lanthanides while keeping the chelating N,Nligand scaffold.…”

Investigation of the slow relaxation of the magnetization dynamics in homoleptic ene-diamido organodysprosium(iii) complexes with K+/arene interactions

“…-2,6], Cp* = C 5 Me 5 ) were also designed by associating DAD-type ligands providing short Dy-N distances with a rigid Cp* moiety. 28 However, in the previous examples, an additional ligand (Cl or THF) was coordinated in the equatorial plane that in turn decreases the axiality. Encouraged by these results, we continued to explore the potential of the DAD ligands.…”

“…Noticeably, such broad signals of " have also been observed in heteroleptic dysprosium DAD 2Me /Cp* complexes with the same DAD 2Me ligand. 28 The corresponding Cole-Cole plots for 1 and 2 (Fig. 4) could be fitted with a generalized Debye model (Tables S2-S3) The  vs. T plot (Fig.…”

Correlation between Slow Magnetic Relaxations and Molecular Structures of Dy(III) Complexes with N5O4 Nona-Coordination

“…Single-molecule magnets (SMMs) are fascinating molecule-based nanomaterials, which are characterized by slow relaxation of magnetization at low temperatures [1][2][3][4][5][6][7][8][9][10]. Magnetic anisotropy plays an essential role in preventing the magnetization flipping; as the orbital angular momentum of 4f electrons is unquenched in the complex formations, each lanthanide(III) (Ln(III)) ion possesses a large magnetic moment correlated with the total angular momentum J, which is defined by the length of the vector summation of the spin angular momentum S and the orbital angular momentum L. The Dy(III) ion is the most fascinating lanthanide ion due to a large total angular momentum of J = 15/2, accompanied by the Kramers characteristic and an oblate type electronic distribution [11][12][13][14][15][16][17][18][19]. The magnetic anisotropy of lanthanide ions is strongly correlated with the electronic repulsion with the crystal field of an appropriate anisotropy; this means an axially stressed crystal field is advantageous for realizing an easy axis anisotropy of the oblate type lanthanide ion.…”