多酸羰基金属衍生物的合成、表征及其催化二氧化碳转化研究

Polyoxometalates (POMs) are metal–oxygen clusters commonly consisting of W, Mo, and V, in high oxidation states. They have a wide variety of applications in such areas as catalysis and medicine and also have wide ranging sizes and properties. They are ideal catalysts for performing organic synthesis chemistry, especially in the field of esterification, condensation and olefin hydration. On the other hand, carbonyl compounds are of important catalysts for conversion of carbon dioxide. It is expected to obtain novel POM-based carbonyl metal derivatives that have excellent catalytic activity in the many organic reactions by combining them. .This project first aims to use their respective features of polyoxoanions and metal-carbonyl moiety M(CO)n (M = Mn, Re or Ir), and obtain POM-supported carbonyl derivatives with novel structure, which would be characterized systemically by IR, UV/Vis, elemental analysis, NMR, and single-crystal X-ray diffraction. Furthermore, the researchers focus on the studies of their physical-chemical properties, the investigation of their optical properties and their applications on catalytic carbon dioxide conversion. Once these target compounds are formed, they can stabilize some unstable components, which, in turn, is benefit for structure determination, and they can also be favor of the exploration of catalytic mechanism from atomic level, so that we can design and synthesize new catalysts with excellent performance. Meanwhile, they can activate the surface oxygen atoms of POMs to make them more reactive and generate new properties, and then exhibit excellent catalysis activity, better molecular recognition performance, higher selectivity and functionality, and so on. .Therefore, this project is expected to provide a platform for the systematic development of POM-based metallocene derivatives, which not only enrich their structural diversities and further broaden their research fields, but also provide technical support for developing novel materials and dealing with the problem of greenhouse gas. In summary, this research has important academic value as well as far-reaching reality significance.

由多酸阴离子与羰基金属化合物在一定条件下反应制备多酸阴离子担载的羰基金属衍生物，对所合成的化合物进行表征和晶体结构测定，研究化合物的物理化学性质，考察催化二氧化碳转化的活性。由于多酸对多种有机反应具有催化活性，而羰基金属化合物对二氧化碳转化具有一定的催化活性，形成多酸阴离子担载的羰基金属衍生物后，可以使某些不稳定的组分稳定化, 有利于确定其结构并对其性质进行研究；可以从原子水平对其结构和催化机理进行深入研究，以便设计出性能更为优良的催化剂；同时形成衍生物后，可以激活多酸阴离子表面的氧原子，使其更具反应活性并可能导致新性质的产生，进而表现出更优良的催化活性、更好的分子识别性能、更高的选择性及更优良的功能性等。开展本项目的研究，不仅可丰富该类化合物的的合成化学，拓宽多酸和羰基金属化合物的研究领域；并可为新型材料制备和温室气体处理等研究领域提供技术支持，具有重要的的理论意义和应用价值。

多酸为一大类多核配合物，由于该类化合物在催化、医药及材料科学等多个领域具有重要应用价值和广泛应用前景，受到了化学家、材料学家的广泛关注。多酸阴离子在一定条件下，可以和含金属-碳键的化合物反应，生成新型含有金属-碳键的化合物进而表现出新的特性。但多酸羰基金属衍生物的研究报道非常有限。本项目的主要研究内容是合成新颖多酸阴离子担载的羰基金属衍生物，对所合成的化合物进行表征和晶体结构测定，研究化合物的物理化学性质，考察催化二氧化碳转化的活性。.在本项基金资助下，从经典多酸前驱体或简单原料出发，采用混合溶剂法与羰基金属化合物反应，通过调控实验条件，成功制备出基于经典Keggin缺位杂多酸、经典Wells-Dawson缺位杂多酸、同多酸盐和非经典多酸盐担载的羰基金属衍生物，共4类10个系列30例具有新型结构的多酸羰基金属衍生物，得到了制备该类化合物的一般方法。同时，系统研究了其中9例化合物催化二氧化碳与环氧化合物的环加成反应活性，这是首次将多酸基羰基金属衍生物用于催化CO2的环加成反应。此外还探索了反应温度，压强，时间，助催化剂和催化剂用量等反应条件对催化反应的影响。在最优条件下进行循环实验，并对研究了CO2与其它反应底物的环加成反应。从中筛选出6例具有良好活性的多酸羰基衍生物。通过DFT计算2例化合物的前线轨道，发现其催化活性位点位于羰基基团，同时结合文献，我们提出了该化合物的催化机理。相关研究结果发表在国际知名期刊Inorg. Chem. ChemCatChem和 Dalton Trans.等上，受到同行的一致认可。通过开展本项目的研究，不仅可丰富了该类化合物的的合成化学，从理论上探索了多酸羰基衍生物的形成机理以利于指导新型化合物的设计与合成，而且拓宽了多酸和羰基金属化合物的研究领域；并为新型材料制备和温室气体处理等研究领域提供技术支持，具有重要的的理论意义和应用价值。