Single-Molecule Magnetism in Tetrametallic Terbium and Dysprosium Thiolate Cages

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• 作者：Daniel N. Woodruff ; Floriana Tuna ; Michael Bodensteiner ; Richard E. P. Winpenny ; Richard A. Layfield
• 刊名：Organometallics
• 出版年：2013
• 出版时间：March 11, 2013
• 年：2013
• 卷：32
• 期：5
• 页码：1224-1229
• 全文大小：341K
• 年卷期：v.32,no.5(March 11, 2013)
• ISSN：1520-6041

文摘

Metalation of ethanethiol by [{(Me₃Si)₂N}₃Ln(渭-Cl)Li(thf)₃] (Ln = Gd, Tb, Dy) in thf produces the thiolate-bridged tetralanthanide compounds [Li(thf)₄][Ln₄{N(SiMe₃)₂}₄(渭-SEt)₈(渭₄-SEt)], where Ln = Gd is [Li(thf)₄][1], Ln = Tb is [Li(thf)₄][2], and Ln = Dy is [Li(thf)₄][3]. Crystallographic studies reveal that the monoanions 1鈥?b>3 are essentially isostructural, consisting of tetrametallic Ln₄ units in which the lanthanides are bridged by 渭-ethanethiolate ligands and the individual lanthanide centers occupy distorted six-coordinate {LnNS₅} coordination environments. The magnetic susceptibility properties of all three compounds were measured in a static (dc) field of 1000 G: the data for the gadolinium anion 1 were reproduced by a model that suggests weak antiferromagnetic and ferromagnetic exchange, with coupling constants of J = 鈭?.09 and +0.04 cm^鈥? (鈭?J formalism). Magnetic susceptibility measurements in a dynamic (ac) field at various frequencies on [Li(thf)₄][2] and [Li(thf)₄][3], in zero dc field, reveal properties characteristic of a single-molecule magnet (SMM). Analysis of the out-of-phase magnetic susceptibility for 2 in zero applied field yielded a small anisotropy barrier of U_eff = 4.6 cm^鈥?, and a similar analysis on 3 produced U_eff = 46 cm^鈥?. Compounds [Li(thf)₄][2] and [Li(thf)₄][3] are rare examples of sulfur-ligated SMMs.