Disklike Hepta- and Tridecanuclear Cobalt Clusters. Synthesis, Structures, Magnetic Properties, and DFT Calculations

详细信息    查看全文

• 作者：Ji-Dong Leng ; Su-Kun Xing ; Radovan Herchel ; Jun-Liang Liu ; Ming-Liang Tong
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：June 2, 2014
• 年：2014
• 卷：53
• 期：11
• 页码：5458-5466
• 全文大小：489K
• 年卷期：v.53,no.11(June 2, 2014)
• ISSN：1520-510X

文摘

The synthesis, structure and magnetic properties are reported of two disklike mixed-valence cobalt clusters [Co^IIICo^II₆(thmp)₂(acac)₆(ada)₃] (1) and [Co^III₂Co^II₁₁(thmp)₄(Me₃CCOO)₄(acac)₆(OH)₄(H₂O)₄](Me₃CCOO)₂路H₂O (2). Heptanuclear complex 1 was prepared by solvothermal reaction of cobalt(II) acetylacetonate (Co(acac)₂), 1,1,1-tris(hydroxymethyl)-propane (H₃thmp), and adamantane-1-carboxylic acid (Hada), whereas by substituting Hada with Me₃CCO₂H, tridecanuclear complex 2 was obtained with an unexpected [Co^III₂Co^II₁₁] core. The core structures of 1 and 2 are related to each other: that of 1 arranges as a centered hexagon of a central Co^III ion surrounded by a [Co^II₆] hexagon, while that of 2 can be described as a larger oligomer based on two vertex-sharing [Co^IIICo^II₆] clusters. Variable-temperature direct-current magnetic susceptibility measurements demonstrated overall ferromagnetic coupling between the Co^II ions within both clusters. The magnetic exchange (J) and magnetic anisotropy (D) values were quantified with appropriate spin-Hamiltonian models and were also supported by density functional theory calculations. The presence of frequency-dependent out-of-phase (蠂_M鈥?/i>) alternating current susceptibility signals at temperatures below 3 K suggested that 2 might be a single-molecule magnet.