Institut Lavoisier de Versailles, UMR 8180, Université de Versailles Saint-Quentin en Yvelines, 45 Avenue des Etats-Unis, 78035 Versailles Cedex, France.
Chemistry. 2011 Dec 9;17(50):14129-38. doi: 10.1002/chem.201101754. Epub 2011 Nov 10.
The ε-PMo(V)(8)Mo(VI)(4)O(36)(OH)(4){Ln(III)(H(2)O)}(4) (Ln=La, Ce, Nd, Sm) polyoxocations, called εLn(4), have been synthesized at room temperature as chloride salts soluble in water, MeOH, EtOH, and DMF. Rare-earth metals can be exchanged, and (31)P NMR spectroscopic studies have allowed a comparison of the affinity of the reduced {ε-PMo(12)} 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 ε-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 ε-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.
ε-PMo(V)(8)Mo(VI)(4)O(36)(OH)(4){Ln(III)(H(2)O)}(4)（Ln=La、Ce、Nd、Sm）聚氧离子，称为 εLn(4)，已作为可溶于水、MeOH、EtOH 和 DMF 的氯化盐在室温下合成。稀土金属可以进行交换，并且（31）P NMR 光谱研究允许比较还原的{ε-PMo(12)}核的亲合力，从而表明 La(III)离子具有最高的亲合力，并且比 Eu(III)重的稀土元素不与 ε-Keggin 多金属氧酸盐反应。DFT 计算为研究的系统的几何形状提供了更深入的了解，从而为那些在晶体形式中存在无序的化合物提供了更准确的信息。通过假设的 La→Gd 取代反应能也得到了证实，Ln 离子超过 Eu 不能与 La 竞争配位 ε-Keggin 钼酸盐的表面。其中两个（Ln=La、Ce）簇已被测试证明，此类系统代表了一类新的高效路易斯酸催化剂家族。这是首次评估聚氧离子的催化活性。
