Single-Molecule Magnetism Properties of the First Strontium-Manganese Cluster [SrMn14O11(OMe)3(O2CPh)18(MeCN)2]

详细信息    查看全文

• 作者：Abhudaya Mishra ; Yulia Pushkar ; Junko Yano ; Vittal K. Yachandra ; Wolfgang Wernsdorfer ; Khalil A. Abboud ; George Christou
• 刊名：Inorganic Chemistry
• 出版年：2008
• 出版时间：March 17, 2008
• 年：2008
• 卷：47
• 期：6
• 页码：1940 - 1948
• 全文大小：1689K
• 年卷期：v.47,no.6(March 17, 2008)
• ISSN：1520-510X

文摘

The preparation and properties of the first strontium-manganese molecular complex are described. The reaction of (NBuⁿ₄)[Mn₄O₂(O₂CPh)₉(H₂O)] (4Mn^III) with Sr(ClO₄)₂ in MeCN/MeOH led to the isolation of [SrMn₁₄O₁₁(OMe)₃(O₂CPh)₁₈(MeCN)₂] (1; 13Mn^III, Mn^II). The structure of 1 consists of two [Mn₄O₃(OMe)] cubane units attached to a central, near-planar, trinuclear [Mn₃O₄] unit, to which are also attached a Mn and a Sr above the plane and a [Mn₂O(OMe)] rhomb below the plane. Peripheral ligation is provided by 18 bridging benzoate and two terminal MeCN groups. Variable-temperature and -field dc magnetization (M) data were collected in the 1.8–10 K and 0.1–4.0 T ranges and fit by matrix diagonalization methods to give S = 9/2, D = −0.50(5) cm⁻¹, and g = 1.88(10), where S is the ground-state spin and D is the axial zero-field splitting parameter. Magnetization versus dc field sweeps at various temperatures and scan rates exhibited hysteresis loops, confirming 1 to be a new single-molecule magnet. Because complex 1 is the initial molecular example of intimately associated Mn and Sr atoms, Sr EXAFS studies have been performed for the first time on a synthetic Sr-containing molecule. This has also allowed comparisons with the EXAFS data on the Sr-substituted water oxidizing complex (WOC) of Photosystem II (PS II), which contains a SrMn₄ complex.