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Rethinking ytterbium(III)-based single-molecule magnets - why trigonal planar doesn't work
Vinicius K Fagundes1, Egidio Dias Viegas1, Marcus J Giansiracusa1
1School of Chemistry, The University of Melbourne, Parkville, Victoria 3010, Australia. marcus.giansiracusa@unimelb.edu.au.
Physical Chemistry Chemical Physics : PCCP
|June 16, 2026
Summary
Zero-field single-molecule magnets (SMMs) are rare for Ytterbium(III) due to inherent electronic structures. Specific symmetries like D5h and D4d are crucial for achieving slow magnetic relaxation in Yb(III) SMMs.
Area of Science:
- Quantum Chemistry
- Materials Science
- Magnetism
Background:
- Ytterbium(III)-based single-molecule magnets (SMMs) typically require applied fields or dilution for magnetic properties.
- Understanding the electronic origins of limited zero-field SMM behavior in Yb(III) is crucial for designing new materials.
Purpose of the Study:
- To investigate the crystal field splitting of Yb(III) in model complexes.
- To elucidate the electronic factors limiting zero-field SMM behavior in Yb(III).
- To identify symmetry criteria for achieving slow magnetic relaxation in Yb(III) SMMs.
Main Methods:
- Utilized Complete Active Space Self-Consistent Field (CASSCF) and CASPT2 methodologies.
- Analyzed symmetry-constrained model complexes with varying equatorial ligand field environments.
- Benchmarked Yb(III) behavior against Erbium(III) complexes.
- Estimated quantum tunnelling of magnetisation (QTM) rates.
Main Results:
- Substantial transverse g-tensor components in Yb(III) lead to rapid zero-field relaxation across most high-symmetry environments.
- Ideal symmetries (D3h, D4h, D6h) do not sufficiently suppress transverse anisotropy for Yb(III) SMMs.
- Only D5h and D4d symmetries show potential for SMM behavior by quenching QTM.
- Erbium(III) complexes exhibit higher g-tensor axiality, explaining their superior zero-field performance.
Conclusions:
- Fundamental electronic differences between Yb(III) and Er(III) explain the lack of zero-field Yb(III) SMMs.
- Stringent symmetry criteria (specifically D5h and D4d) are necessary for designing Yb(III) based zero-field SMMs.
- Findings provide guidance for future synthetic efforts targeting Yb(III) SMMs.
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