Lanthanide Polyoxocationic Complexes: Experimental and Theoretical Stability Studies and Lewis Acid Catalysis
Lanthanide Polyoxocationic Complexes: Experimental and Theoretical Stability Studies and Lewis Acid Catalysis
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DOI：
10.1002/chem.201101754
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发表时间：
2011-12-01
影响因子：
4.3
通讯作者：
Dolbecq, Anne
中科院分区：
文献类型：
--
作者：
El Moll, Hani;Nohra, Brigitte;Dolbecq, Anne
在室温下合成了[P-（PMo_8Mo_4O_（36））-Mo-V-O-VI（OH）（4）{Ln（III）（H_2O）}（4）]（5+）（Ln=La，Ce，Nd，Sm）多金属氧配位化合物，简称Ln（4）。稀土金属可以被交换，并且P-31 NMR光谱研究已经允许比较还原的{ε-PMo 12}核的亲和力，从而表明La-III离子具有最高的亲和力，并且比Eu-III重的稀土不与ε-Keggin多氧六环酸盐反应。DFT计算提供了一个更深入的了解所研究的系统的几何形状，从而提供更准确的信息，这些化合物遭受无序的结晶形式。La → Gd取代反应能量的假设也证实了Eu以外的Ln离子不能与La竞争配位。这些簇中的两个（Ln=La，Ce）已经被测试以证明这样的系统是新的有效的刘易斯酸催化剂家族的代表。这是首次对多氧阳离子的催化活性进行评价。
The [epsilon-(PMo8Mo4O36)-Mo-V-O-VI(OH)(4){Ln(III)(H2O)}(4)](5+) (Ln=La, Ce, Nd, Sm) polyoxocations, called epsilon Ln(4), have been synthesized at room temperature as chloride salts soluble in water, MeOH, EtOH, and DMF. Rare-earth metals can be exchanged, and P-31 NMR spectroscopic studies have allowed a comparison of the affinity of the reduced {epsilon-PMo12} core, thus showing that the La-III ions have the highest affinity and that rare earths heavier than Eu-III do not react with the epsilon-Keggin polyoxometalate. DFT calculations provide a deeper insight into the geometries of the systems studied, thereby giving more accurate information on those compounds that suffer from disorder in crystalline form. It has also been confirmed by the hypothetical La -> Gd substitution reaction energy that Ln ions beyond Eu cannot compete with La in coordinating the surface of the epsilon-Keggin molybdate. Two of these clusters (Ln=La, Ce) have been tested to evidence that such systems are representative of a new efficient Lewis acid catalyst family. This is the first time that the catalytic activity of polyoxocations has been evaluated.