From a Dy(III) Single Molecule Magnet (SMM) to a Ferromagnetic [Mn(II)Dy(III)Mn(II)] Trinuclear Complex

Abstract

The Schiff base compound 2,2'-{[(2-aminoethyl)imino]bis[2,1-ethanediyl-nitriloethylidyne]}bis-2-hydroxy-benzoic acid (H(4)L) as a proligand was prepared in situ. This proligand has three potential coordination pockets which make it possible to accommodate from one to three metal ions allowing for the possible formation of mono-, di-, and trinuclear complexes. Reaction of in situ prepared H(4)L with Dy(NO(3))(3)·5H(2)O resulted in the formation of a mononuclear complex [Dy(H(3)L)(2)](NO(3))·(EtOH)·8(H(2)O) (1), which shows SMM behavior. In contrast, reaction of in situ prepared H(4)L with Mn(ClO(4))(2)·6H(2)O and Dy(NO(3))(3)·5H(2)O in the presence of a base resulted in a trinuclear mixed 3d-4f complex (NHEt(3))(2)[Dy{Mn(L)}(2)](ClO(4))·2(H(2)O) (2). At low temperatures, compound 2 is a weak ferromagnet. Thus, the SMM behavior of compound 1 can be switched off by incorporating two Mn(II) ions in close proximity either side of the Dy(III). This quenching behavior is ascribed to the presence of the weak ferromagnetic interactions between the Mn(II) and Dy(III) ions, which at T > 2 K act as a fluctuating field causing the reversal of magnetization on the dysprosium ion. Mass spectrometric ion signals related to compounds 1 and 2 were both detected in positive and negative ion modes via electrospray ionization mass spectrometry. Hydrogen/deuterium exchange (HDX) reactions with ND(3) were performed in a FT-ICR Penning-trap mass spectrometer.

Coupling Strategies to Enhance Single-Molecule Magnet Properties of Erbium–Cyclooctatetraenyl Complexes

“…In this temperature regime, neighboring magnetic centers act on each other merely as sources of fluctuating magnetic field resulting in the increase of the relaxation rate at each of them. 17 The same effect of the surrounding molecules is expected to enhance magnetic relaxation in the (undiluted) mononuclear [Er III (COT) 2 ] − compound. The increased magnetic blocking observed in 3 can be attributed to the different crystal packing compared to the mononuclear [Er III (COT) 2 ] − compound, leading to a smaller effect of the random magnetic field created by the crystal environment.…”

Systematic studies of hexanuclear {MIII4LnIII2} complexes (M = Fe, Ga; Ln = Er, Ho): structures, magnetic properties and SMM behavior

“…18,19 The Cole-Cole plots for 2 under 750 Oe dc field (Fig. S6) show symmetric semicircles and can be fitted to a generalized Debye function with α = 0.058 (at 6.2 K) -0.22 (at 2.0 K).…”

“…25 Furthermore, weak 3d-4f interactions lead to the trigger of the QTM and diminishing the energy barrier, while strong 3d-4f exchange couplings suppress the QTM under zero dc field and slow down the relaxation of magnetization. [18][19][20][21] The Cole-Cole plots for 1 under a 500 Oe dc field can be fitted based on a generalized Debye function (Fig. S4).…”

“…[5][6][7][8][9] Although many studies on 4f-4f or 3d-3d interactions have been reported, [10][11][12][13][14][15][16][17] research on 3d-4f exchange interactions is less developed. [18][19][20][21][22][23][24] Furthermore, according to the model of free-ion electron densities for all Ln III ions, the shape of the 4f electron density for the Dy III ion is oblate, while that for Er III is prolate. 25 Therefore, in order to maximize the magnetic anisotropy, a sandwich-type ligand geometry with harder or negatively-charged ligand atoms predominantly in axial positions is expected to be appropriate for Dy III , while a ligand field with such harder atoms mainly in an equatorial coordination positions should be necessary for Er III .…”

Field-induced internal Fe and Ln spin reorientation in butterfly{Fe3LnO2}(LnBadía-Romano1, Bartolomé2, Bartolomé3 et al. 2013Phys. Rev. B212140View full textAdd to dashboardCite

“…The coordination sphere of the Dy atom consists of eight oxygen atoms. In several compounds with Dy surrounded by a similar coordination, the ground state has been found experimentally to be axially anisotropic, with g z g x = g y 0, and an energy difference from the ground doublet to the first excited doublet ranging between 60 and 80 K. 8,44 In the absence of direct determination of the ground-state g * -tensor components, we have estimated them by means of an ab initio relativistic quantum chemistry method based on Post-Hartree-Fock calculations (see Supplemental Material, Sec. I).…”