Significant Enhancement of Energy Barriers in Dinuclear Dysprosium Single-Molecule Magnets Through Electron-Withdrawing Effects

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• 作者：Fatemah Habib ; Gabriel Brunet ; Veacheslav Vieru ; Ilia Korobkov ; Liviu F. Chibotaru ; Muralee Murugesu
• 刊名：Journal of the American Chemical Society
• 出版年：2013
• 出版时间：September 11, 2013
• 年：2013
• 卷：135
• 期：36
• 页码：13242-13245
• 全文大小：305K
• 年卷期：v.135,no.36(September 11, 2013)
• ISSN：1520-5126

文摘

The effect of electron-withdrawing ligands on the energy barriers of Single-Molecule Magnets (SMMs) is investigated. By introducing highly electron-withdrawing atoms on targeted ligands, the energy barrier was significantly enhanced. The structural and magnetic properties of five novel SMMs based on a dinuclear {Dy₂} phenoxo-bridged motif are explored and compared with a previously studied {Dy₂} SMM (1). All complexes share the formula [Dy₂(valdien)₂(L)₂]路solvent, where H₂valdien = N1,N3-bis(3-methoxysalicylidene) diethylenetriamine, the terminal ligand L = NO₃^{鈥?/sup> (1), CH₃COO鈥?/sup> (2), ClCH₂COO鈥?/sup> (3), Cl₂CHCOO鈥?/sup> (4), CH₃COCHCOCH₃鈥?/sup> (5), CF₃COCHCOCF₃鈥?/sup> (6), and solvent = 0.5 MeOH (4), 2 CH₂Cl₂ (5). Systematic increase of the barrier was observed for all complexes with the most drastic increase seen in 6 when the acac ligand of 5 was fluorinated resulting in a 7-fold enhancement of the anisotropic barrier. Ab initio calculations reveal more axial g tensors as well as higher energy first excited Kramers doublets in 4 and 6 leading to higher energy barriers for those complexes.}