New deployment of molybdenum giant cluster compounds

本研究旨在：(1)建立一条新的有用的钼巨团簇合成路线，拓宽巨团簇的应用领域；(2)合成含多种金属阳离子的巨团簇新化合物；(3)开发巨团簇的新应用。为了实现这一目标，我们首先尝试建立一种新的钼巨团溶液的制备路线，该溶液不含碱金属反阳离子或由于制备过程而产生的反应残渣等阻碍物质，从而使钼巨团的应用更加广泛。将离子交换技术与质子在贵金属（H/Pd或H/Pt）上的还原反应相结合，可以建立这一途径。然后，我们尝试从上述方法得到的巨团溶液中制备新的巨团化合物。通过在溶液中加入所需的金属阳离子，成功地合成了各种化合物。其中部分材料的晶体结构通过单晶XRD分析确定。测定结果表明存在一种具有椭圆畸变的新型凹形{Mo154}星团。这一发现可能对材料构建具有重要意义，因为它使用巨大的集群物种作为构建块。此外，我们试图将巨大团簇的无定形特性应用于制备成分控制良好的均质混合物，这些混合物适合作为低温合成的起始材料。我们可以证实，由巨团簇溶液制备的非晶态混合物在较低温度下提供了多种功能材料。

This research aimed at (1) establishment of a novel and useful synthetic route for molybdenum giant clusters, which route would broaden the application field of the giant clusters, (2) syntheses of novel compounds of the giant clusters with various metal cations, and (3) development of new applications of the giant clusters.In order to achieve the aim we first tried to establish a novel preparation route of molybdenum giant cluster solution, which solution contained no impediment species, such as alkali metal counter cation or reaction residue due to preparation procedures, and would thus become comfortable for broadened applications of the giant clusters. The route could be established by combining an ion-exchange technique and a reducing reaction with proton on noble metal (H/Pd or H/Pt).We then tried to prepare novel compounds of the giant clusters from the giant cluster solution obtained by the above method. Various compounds were successfully synthesized by adding desired metal cations to the solution. For some of them the crystal structures were determined by single crystal XRD analysis. The determination revealed the existence of a novel lacunary type of {Mo154} cluster with elliptic distortion. This finding might be of importance for material construction, which uses giant cluster species as building blocks.Furthermore, we tried to apply the amorphous character of the giant clusters, which results from difficulties of positioning extremely large species into a highly ordered state, to preparation of compositionally well-controlled homogeneous mixtures, which are suitable for a starting material of low temperature syntheses. We could confirm that the amorphous mixtures prepared from the giant cluster solution provided various kinds of functional materials at lower temperatures.