Adducts of Tris(alkyl) Holmium(III) Showing Magnetic Relaxation
- 16 April 2020
- journal article
- research article
- Published by American Chemical Society (ACS) in Inorganic Chemistry
- Vol. 59 (9), 5835-5844
- https://doi.org/10.1021/acs.inorgchem.9b03264
Abstract
In the series of the adducts of tris(alkyl) HoIII complexes, Ho(CH2SiMe3)3(THF)2 (1Ho-THF, Me = methyl) can exhibit slow magnetic relaxation under a zero applied direct current (DC) field with the energy barrier Δ/kB of 76 K, which is one of the highest in the non-Kramers ion HoIII-based single-ion magnets (SIMs). The DC field-dependence of relaxation time for 1Ho-THF indicates the occurrence of direct relaxation process at low temperature under certain DC fields. 1Ho-THF stands out in the series of 1Ln-THF (Ln = Tb, Dy, Ho, Er, Tm), wherein Dy congener is another SIM in the absence of a DC field with the relaxation barrier of 40 K, while Tb and Er congeners are field-induced SIMs. Further substitutions of the two trans-THF in 1Ho-THF by other neutral ligands such as quinuclidine, tricyclohexylphosphine oxide, and 3,5-lutidine afforded Ho(CH2SiMe3)3(quinuclidine)2 (2Ho-QN), Ho(CH2SiMe3)3(OPCy3)2 (3Ho-OPCy3), and Ho(CH2SiMe3)3(lutidine)3 (4Ho-Lut), respectively. The former two possess analogous structures to 1Ho-THF with two trans-arranged neutral ligands, and the latter one has three cis-lutidine coordinated. The fast quantum tunneling effect swamps the magnetic relaxation for the above three derivatives, so slow relaxation could not be observed under experimental conditions, even when a certain DC field was applied.Funding Information
- Peking University
- Ministry of Science and Technology of the People's Republic of China (2017YFA0204903, 2017YFA0206301)
- National Natural Science Foundation of China (21290171, 21571008, 21621061, 91422302)
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