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Title: | Effect of coordination geometry on the magnetic properties of a series of Ln2 and Ln4 hydroxo clusters |
Author: | Rasamsetty, Amaleswari Das, Chinmoy Sañudo Zotes, Eva Carolina Shanmugam, Maheswaran Baskar, Viswanathan |
Keywords: | Terres rares Imants Magnetisme Rare earths Magnets Magnetism |
Issue Date: | 7-Dec-2017 |
Publisher: | Royal Society of Chemistry |
Abstract: | A series of three isostructural tetranuclear complexes with the general molecular formula [Ln4(µ3-OH)4(L)4(µ2-piv)4(MeOH)4] (Ln = Gd 1, Dy 2 and Ho 3; LH = [1,3-bis(o-methoxyphenyl)-propane-1,3-dione]) were isolated and unambiguously characterized by single crystal XRD. Under similar reaction conditions, simply changing the co-ligand from pivalate to 2,6-bis(hydroxymethyl)-p-cresol (LH'3) led to the isolation of dinuclear Ln(III) complexes with the general molecular formula [Ln2(L)4(µ2-LH'2)2]·4DMF (Ln =Gd 4, Dy 5 and Ho 6). Direct current magnetic susceptibility data studies on the polycrystalline sample of 1-6 and the results reveal the existence of weak antiferromagnetic exchange interactions between the lanthanide ions in 1 which is evident from the spin Hamiltonian (SH) parameters (J1 = −0.055 cm−1 and g = 2.01) extracted by fitting χMT(T). On the other hand, though complex 4 exhibits weak antiferromagnetic coupling ( J1 = −0.048 cm−1 and g = 1.99) between the Gd(III) ions, the χMT (T ) data of complexes 5 and 6 unambiguously disclose the presence of ferromagnetic interactions between Dy(III) and Tb(III) ions at lower temperature. Magnetization relaxation dynamics studies performed on 2 show frequency dependent out-of-phase susceptibility signals in the presence of an optimum external magnetic field of 0.5 kOe. In contrast, complex 5 shows slow magnetization relaxation with an effective energy barrier (Ueff) of 38.17 cm−1 with a pre-exponential factor (τ0) of 1.85 × 10−6 s. The magnetocaloric effect (MCE) of complexes 1 and 4 was extracted from the detailed magnetization measurement and the change in the magnetic entropy (−ΔSm) of 1 and 4 was found to be 25.57 J kg−1 K−1 and 12.93 J kg−1 K−1,respectively, at 3.0 K for ΔH = 70 kOe. |
Note: | Versió postprint del document publicat a: https://doi.org/10.1039/c7dt00172j |
It is part of: | Dalton Transactions, 2017, vol. 47, num. 5, p. 1726-1738 |
URI: | http://hdl.handle.net/2445/154387 |
Related resource: | https://doi.org/10.1039/c7dt00172j |
ISSN: | 1477-9226 |
Appears in Collections: | Articles publicats en revistes (Química Inorgànica i Orgànica) |
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