Tetranuclear Lanthanide(III) Complexes in a Seesaw Geometry: Synthesis, Structure, and Magnetism

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• 作者：Joydeb Goura ; James P. S. Walsh ; Floriana Tuna ; Vadapalli Chandrasekhar
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：April 7, 2014
• 年：2014
• 卷：53
• 期：7
• 页码：3385-3391
• 全文大小：428K
• 年卷期：v.53,no.7(April 7, 2014)
• ISSN：1520-510X

文摘

The reaction of 2-methoxy-6-(pyridin-2-ylhydrazonomethyl)phenol (LH) with Ln(III) (Ln = Gd, Tb, Dy, Ho) salts in the presence of an excess of triethylamine afforded [Gd₄(L)₄(渭₄-OH)(渭₃-OH)₂(NO₃)₄]路(NO₃)路4CH₃CN路CH₃OH路2H₂O (1), [Tb₄(L)₄(渭₄-OH)(渭₃-OH)₂(NO₃)₄]路(NO₃)路4CH₃CN路3H₂O (2), [Dy₄(L)₄(渭₄-OH)(渭₃-OH)₂(NO₃)₄]路(NO₃)路6CH₃CN路H₂O (3), and [Ho₄(L)₄(渭₄-OH)(渭-OH)₂(NO₃)₄]路(NO₃)路8CH₃CN路3CH₃OH路2H₂O (4). All four complexes contain a monocationic tetranuclear core with a unique seesaw topology. The tetranuclear assembly is formed through the coordination of four [L]^{鈭?/sup>, one 渭₄-OH, two 渭₃-OH, and four chelating nitrate ligands, with a charge-balancing nitrate counteranion. Magnetic studies reveal a weak antiferromagnetic coupling throughout the series. Compound 1 can be modeled well with an isotropic exchange between all centers parametrized by J = 鈭?.09 cm鈥?. Compound 3 exhibits slow magnetic relaxation at low temperatures.}