Synthesis and Structural Characterization of Lanthanide Containing Polyoxoanions Functionalized by Peroxo Groups, and Investigation of Their Catalytic Properties

我们提出合成新型的镧系中心取代的多钨酸盐，其末端的水相配体已被过氧基团取代。到目前为止，还没有发现这样的物种。我们还将研究这种新型的聚氧乙烯酸酯（POM）的均相和非均相氧化催化性能。我们将研究镧系元素离子与各种水溶性聚钨酸盐前体的相互作用，然后使用过氧化氢水溶液进行官能化。我们最初的重点将是已知镧系元素-POM的官能化，例如，壮观的含20-铈的100-钨锗酸盐[Ce 20 Ge 10 W100 O376（OH）4（H2O）30]56- 21该物种具有与20个铈中心相关的总共30个末端水配体，因此代表了用过氧基团官能化的良好候选者。我们的新型镧系元素-过氧-POM将像往常一样通过单晶X射线衍射，FTIR，TGA-DSC，多核NMR（例如183 W，31 P，29 Si）和元素分析进行表征。初步的催化试验（例如烯烃的过氧化物氧化）也将在雅各布斯大学进行。将镧系元素引入到缺位的聚钨酸盐框架中已经导致了几种在发光、磁性和刘易斯酸型催化领域具有有趣性质的多金属氧酸盐。由于其较大的尺寸和配位数，与3d过渡金属相比，镧系离子不能完全插入到缺位POM前体的空位中，通常导致2个或更多个末端、空间可及且不稳定的水配体。这反过来又允许那些水分子被有机配体（包括手性的）或用于与其它POM片段配位，导致非常大的离散的分子结构或延伸的框架。到目前为止，一些过氧-POM是已知的，它们是非常好的氧化催化剂。29另一方面，没有镧系元素-过氧-POM的报道。我们相信这种POM应该存在，因为侧-对-过氧桥接的镧系元素基配位络合物的形成是众所周知的。

We propose to synthesize novel polyoxotungstates substituted by lanthanide centers for which the terminal aqua ligands have been substituted by peroxo groups. To date no such species are known at all. We will also investigate the homogeneous and heterogeneous oxidation catalysis properties of this novel subclass of polyoxometalates (POMs). We will investigate the interaction of lanthanide ions with a variety of water-soluble polytungstate precursors, followed by functionalization using aqueous hydrogen peroxide. Our initial focus will be on the functionalization of known lanthanide-POMs, e.g. the spectacular 20-cerium containing 100- tungstogermanate [Ce20Ge10W100O376(OH)4(H2O)30]56- published very recently by our group.21 This species has a total of 30 terminal aqua ligands associated with the 20 cerium centers and hence represents a good candidate for functionalization with peroxo groups. Our novel lanthanide-peroxo-POMs will be characterized as usual by single-crystal X-ray diffraction, FTIR, TGA-DSC, multinuclear NMR (e.g. 183W, 31P, 29Si) and elemental analysis. The preliminary catalytic tests (e.g. peroxide-based oxidation of olefins) will also be carried out at Jacobs University. Incorporation of lanthanides into lacunary polytungstate frameworks has already resulted in several POMs with interesting properties in the areas of luminescence, magnetism, and Lewis acid-type catalysis. Due to their larger size and coordination number, compared to 3d transition metals, lanthanide ions cannot be fully inserted into the vacant sites of the lacunary POM precursors, usually resulting in 2 or more terminal, sterically accessible and labile water ligands. This in turn allows for substitution of those water molecules by organic ligands (incl. chiral ones) or for coordination to other POM fragments leading to very large discrete, molecular architectures or extended frameworks. To date some peroxo-POMs are known and they are very good oxidation catalysts.29 On the other hand, no lanthanide-peroxo-POMs have ever been reported. We believe that such POMs should exist, as formation of side-on -peroxo bridged lanthanide based coordination complexes are well known.30