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Theoretical investigations on mixed-valence dilanthanide complexes (Cp)LnI (Ln = Tb, Dy, and Ho) indicate that the total spin of the 4f shell couples preferentially to the σ electron spin and then to the orbital angular momentum, improving the strength of spin-orbit coupling (SOC) for each magnetic center. On the other hand, the concentration of negative charges containing the delocalized σ electron in the axial direction leads to a large crystal-field (CF) splitting. Both strong SOC and large CF splitting lead to the largest energy barrier of such complexes up to now. In addition, our calculations show that the introduction of σ electron can better suppress the quantum tunneling of magnetization in the ground spin-orbit state, and the of (Cp)LnI is expected to originate from the contribution of both Ln ions under such strong Ln-σ exchange coupling.
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http://dx.doi.org/10.1021/acs.jpca.2c08526 | DOI Listing |
J Am Chem Soc
July 2024
Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.
Mixed-valence dilanthanide complexes of the type (Cp)LnI (Cp = pentaisopropylcyclopentadienyl; Ln = Gd, Tb, Dy) featuring a direct Ln-Ln σ-bonding interaction have been shown to exhibit well-isolated high-spin ground states and, in the case of the Tb and Dy variants, a strong axial magnetic anisotropy that gives rise to a large magnetic coercivity. Here, we report the synthesis and characterization of two new mixed-valence dilanthanide compounds in this series, (Cp)LnI (; Ln = Ho, Er). Both compounds feature a Ln-Ln bonding interaction, the first such interaction in any molecular compounds of Ho or Er.
View Article and Find Full Text PDFJ Am Chem Soc
April 2023
Naval Air Warfare Center, Weapons Division, Research Department, Chemistry Division, US Navy, China Lake, California 93555, United States.
The recent discovery of metal-metal bonding and valence delocalization in the dilanthanide complexes (Cp)LnI (Cp = pentaisopropylcyclopentadienyl; Ln = Y, Gd, Tb, Dy) opened up the prospect of harnessing the 4f5d electron configurations of non-traditional divalent lanthanide ions to access molecules with novel bonding motifs and magnetism. Here, we report the trinuclear mixed-valence clusters (Cp)LnHI (, Ln = Y, Gd), which were synthesized via potassium graphite reduction of the trivalent clusters (Cp)LnHI. Structural, computational, and spectroscopic analyses support valence delocalization in resulting from a three-center, one-electron σ bond formed from the 4d and 5d orbitals on Y and Gd, respectively.
View Article and Find Full Text PDFJ Phys Chem A
April 2023
Jiangsu Key Lab for NSLSCS, School of Physical Science and Technology, Nanjing Normal University, Nanjing 210023, P. R. China.
Theoretical investigations on mixed-valence dilanthanide complexes (Cp)LnI (Ln = Tb, Dy, and Ho) indicate that the total spin of the 4f shell couples preferentially to the σ electron spin and then to the orbital angular momentum, improving the strength of spin-orbit coupling (SOC) for each magnetic center. On the other hand, the concentration of negative charges containing the delocalized σ electron in the axial direction leads to a large crystal-field (CF) splitting. Both strong SOC and large CF splitting lead to the largest energy barrier of such complexes up to now.
View Article and Find Full Text PDFChem Soc Rev
November 2022
State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China.
Lanthanide (Ln) compounds represent a unique chemical platform for developing high-temperature single-molecule magnets (SMMs). The shift in research focus from increasing the magnetic anisotropy barrier () to raising the blocking temperature () has upgraded the design criteria from considering only the static crystal field (CF) to paying attention to the effects of molecular vibrations beyond the first coordination environment on the relaxation of magnetization. Although the realization of high working temperatures for Ln SMMs remains a formidable challenge, recent remarkable advances in dimetallofullerenes (di-EMFs) with Ln ions and mixed-valence dilanthanide complexes both feature single-electron Ln-Ln bonds to afford room-temperature molecular magnets.
View Article and Find Full Text PDFScience
January 2022
Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA.
Magnetic effects of lanthanide bonding Lanthanide coordination compounds have attracted attention for their persistent magnetic properties near liquid nitrogen temperature, well above alternative molecular magnets. Gould . report that introducing metal-metal bonding can enhance coercivity.
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