Diverse Ligand‐Functionalized Mixed‐Valent Hexamanganese Sandwiched Silicotungstates with Single‐Molecule Magnet Behavior |
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| Authors: | Han Xue Prof?Dr Jun‐Wei Zhao Rui Pan Prof Bai‐Feng Yang Prof?Dr Guo‐Yu Yang Prof?Dr Hong‐Sheng Liu |
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| Institution: | 1. MOE Key Laboratory of Cluster Science, School of Chemistry, Beijing Institute of Technology, Beijing, P. R. China;2. Henan Key Laboratory of Polyoxometalate Chemistry, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan, P. R. China;3. Department of Chemistry, Key Laboratory for Preparation and Application of Ordered Structural Materials of Guangdong Province, Shantou University, Shantou, Guangdong, P. R. China;4. Key Laboratory of Oilfield Applied Chemistry, College of Heilongjiang Province, Daqing Normal University, Daqing, Heilongjiang, P. R. China |
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| Abstract: | Under hydrothermal conditions, replacement of the water molecules in the MnIII4MnII2O4(H2O)4]8+ cluster of mixed‐valent Mn6 sandwiched silicotungstate (B‐α‐SiW9O34)2MnIII4MnII2O4(H2O)4]12? ( 1 a ) with organic N ligands led to the isolation of five organic–inorganic hybrid, Mn6‐substituted polyoxometalates (POMs) 2 – 6 . They were all structurally characterized by IR spectroscopy, elemental analysis, thermogravimetric analysis, diffuse‐reflectance spectroscopy, and powder and single‐crystal X‐ray diffraction. Compounds 2 – 6 represent the first series of mixed‐valent {MnIII4MnII2O4(H2O)4?n(L)n} sandwiched POMs covalently functionalized by organic ligands. The preparation of 1 – 6 not only indicates that the double‐cubane {MnIII4MnII2O4(H2O)4?n(L)n} clusters are very stable fragments in both conventional aqueous solution and hydrothermal systems and that organic functionalization of the MnIII4MnII2O4(H2O)4]8+ cluster by substitution reactions is feasible, but also demonstrates that hydrothermal environments can promote and facilitate the occurrence of this substitution reaction. This work confirms that hydrothermal synthesis is effective for making novel mixed‐valent POMs substituted with transition‐metal (TM) clusters by combining lacunary Keggin precursors with TM cations and tunable organic ligands. Furthermore, magnetic measurements reveal that 3 and 6 exhibit single‐molecule magnet behavior. |
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| Keywords: | cluster compounds hydrothermal synthesis manganese mixed-valent compounds polyoxometalates |
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