Application of the Hubbard Model to Cp*2Yb(bipy), a Model System for Strong Exchange Coupling in Lanthanide Systems
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- 作者：Wayne W. Lukens ; Nicola Magnani ; Corwin H. Booth
- 刊名：Inorganic Chemistry
- 出版年：2012
- 出版时间：October 1, 2012
- 年：2012
- 卷：51
- 期：19
- 页码：10105-10110
- 全文大小：286K
- 年卷期：v.51,no.19(October 1, 2012)
- ISSN：1520-510X
文摘
Exchange coupling is quantified in lanthanide (Ln) single-molecule magnets (SMMs) containing a bridging N23鈥?/sup> radical ligand and between [Cp*2Yb]+ and bipy鈥⑩€?/sup> in Cp*2Yb(bipy), where Cp* is pentamethylcyclopentadienyl and bipy is 2,2鈥?bipyridyl. In the case of these lanthanide SMMs, the magnitude of exchange coupling between the Ln ion and the bridging N23鈥?/sup>, 2J, is very similar to the barrier to magnetic relaxation, Ueff. A molecular version of the Hubbard model is applied to systems in which unpaired electrons on magnetic metal ions have direct overlap with unpaired electrons residing on ligands. The Hubbard model explicitly addresses electron correlation, which is essential for understanding the magnetic behavior of these complexes. This model is applied quantitatively to Cp*2Yb(bipy) to explain its very strong exchange coupling, 2J = 鈭?.11 eV (鈭?20 cm鈥?). The model is also used to explain the presence of strong exchange coupling in Ln SMMs in which the lanthanide spins are coupled via bridging N23鈥?/sup> radical ligands. The results suggest that increasing the magnetic coupling in lanthanide clusters could lead to an increase in the blocking temperatures of exchange-coupled lanthanide SMMs, suggesting routes to rational design of future lanthanide SMMs.