Tuning the Origin of Magnetic Relaxation by Substituting the 3d or Rare-Earth Ions into Three Isostructural Cyano-Bridged 3d鈥?f Heterodinuclear Compounds

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• 作者：Yan Zhang ; Zhen Guo ; Shuang Xie ; Hui-Li Li ; Wen-Hua Zhu ; Li Liu ; Xun-Qing Dong ; Wei-Xun He ; Jin-Chao Ren ; Ling-Zhi Liu ; Annie K. Powell
• 刊名：Inorganic Chemistry
• 出版年：2015
• 出版时间：November 2, 2015
• 年：2015
• 卷：54
• 期：21
• 页码：10316-10322
• 全文大小：419K
• ISSN：1520-510X

文摘

Three isostructural cyano-bridged 3d鈥?f compounds, [YFe(CN)₆(hep)₂(H₂O)₄] (1), [DyFe(CN)₆(hep)₂(H₂O)₄] (2), and [DyCo(CN)₆(hep)₂(H₂O)₄] (3), were successfully assembled by site-targeted substitution of the 3d or rare-earth ions. All compounds have been structurally characterized to display slightly distorted pentagonal-bipyramidal local coordination geometry around the rare-earth ions. Magnetic analyses revealed negligible magnetic coupling in compound 1, antiferromagnetic intradimer interaction in 2, and weak ferromagnetic coupling through dipolar鈥揹ipolar interaction in 3. Under an applied direct-current (dc) field, 1 (H_dc = 2.5 kOe, 蟿₀ = 1.3 脳 10^鈥? s, and U_eff/k_B = 23 K) and 3 (H_dc = 2.0 kOe, 蟿₀ = 7.1 脳 10^鈥?1 s, and U_eff/k_B = 63 K) respectively indicated magnetic relaxation behavior based on a single [Fe^III]_LS ion and a Dy^III ion; nevertheless, 2 (H_dc = 2.0 kOe, 蟿₀ = 9.7 脳 10^鈥? s, and U_eff/k_B = 23 K) appeared to be a single-molecule magnet based on a cyano-bridged DyFe dimer. Compound 1, which can be regarded as a single-ion magnet of the [Fe^III]_LS ion linked to a diamagnetic Y^III ion in a cyano-bridged heterodimer, represents one of the rarely investigated examples based on a single Fe^III ion explored in magnetic relaxation behavior. It demonstrated that the introduction of intradimer magnetic interaction of 2 through a cyano bridge between Dy^III and [Fe^III]_LS ions negatively affects the energy barrier and 蠂鈥?T) peak temperature compared to 3.