取代型金属氧簇的合成、结构及催化性能研究

Lacunary oxo-metal cluster is a kind of soft basic ligands. They can react with metal ions, yielding substituted oxo-metal clusters. The electron density and the catalytic properties of the metal ions can be tuned via the substitution. In the cyclopropanation of alkenes with α-diazo carbonyl compounds as the carbene sources, the electronic properties of metal catalysts have great impact on the activation of α-diazo carbonyl compounds and the activity of the intermediate M=C. Thus, rapid and effective cyclopropanation of alkenes can be realized by varying the electronic properties of active metal centre using lacunary oxo-metal cluster as the ligand. In this project, a series of substituted oxo-metal clusters will be synthesized using abundant metal salts or oxides as the substituting metal sources and lacunary oxo-metal clusters as the ligands. The synthetic process will proceed via lacunary direction of lacunary sites of the ligands. Many parameters of the reactions such as temperature, acidity, as well as the concentration and ratio of reactants should be optimized carefully. The substituted oxo-metal clusters will be characterized thoroughly. The following step will focus on the catalytic properties of these substituted oxo-metal clusters for the cyclopropanation of alkenes. The effects of ligands and substituting metals on the catalytic reactions will be examined, and the relationship between the structures and catalytic properties of substituted oxo-metal clusters will be disclosed. Finally, the substituted catalysts with high activities and selectivities will be selected for generality and mechanism study. The project will be scientifically significant for the developments of novel catalysts for alkene cyclopropanation and catalysis chemistry of oxo-metal clusters.

缺位金属氧簇是一类良好的软碱配体，可与金属离子配位生成取代型金属氧簇，从而调节金属中心的电子密度及相关的催化性能。在α-重氮羰基化合物参与的烯烃环丙烷化反应中，金属催化剂活性中心的电子效应对α-重氮羰基化合物的活化及中间体M=C双键的反应活性有重要影响。因此，可以通过缺位金属氧簇配体来调节催化剂活性金属中心的性质，进而快速、有效地实现烯烃环丙烷化。本项目将以“缺位点结构导向”思想为指导，以廉价金属盐/氧化物为金属源，通过调节反应体系的温度、酸度、反应物浓度及配比等条件合成一系列含缺位金属氧簇配体的取代型金属氧簇，并对其结构进行详细表征。重点研究这些取代型金属氧簇在烯烃环丙烷化反应中的催化性能。考察缺位金属氧簇类型及取代金属属性对催化反应的影响，建立构效关系。筛选出催化性能优良的催化剂，研究其普适性和反应机理。本项目在发展烯烃环丙烷化新型催化剂及金属氧簇催化化学领域具有重要的科学意义。

金属氧簇化合物因其丰富的结构、灵活的电子流动性及方便的可修饰性在催化化学中受到广泛关注，尤其在酸催化和氧化催化反应中发挥不可忽视的作用。而取代型金属氧簇因第二金属的引入，增加了新的催化活性位，使其促进的反应类型得到进一步延伸。项目最先以烯烃的环丙化为探针反应，对取代型金属氧簇进行研究，经过对催化剂结构的调整及催化反应条件的优化，只获得了中等的催化反应结果。项目继而转向金属氧簇基有机-无机杂化催化材料的设计合成及其在染料降解和醇类的氧化中的光催化性能研究，结果发现3-bpo和萘酰亚胺配体参与的材料具有较好的光催化活性,为进一步研究金属氧簇类催化剂在光催化反应中的应用打下坚实的基础。