New deployment of molybdenum giant cluster compounds

本研究旨在(1)建立一条新颖实用的钼巨簇合成路线，拓宽钼巨簇的应用领域；(2)合成各种金属阳离子的新型钼巨簇化合物；(3)开发钼巨簇的新应用。为了实现这一目标，我们首先尝试建立一条新的钼巨簇溶液的制备路线，该路线不含碱金属对抗或制备过程中的反应残留物等阻碍物种，从而适合于巨簇的广泛应用。将离子交换技术和质子在贵金属(H/Pd或H/Pt)上的还原反应相结合，建立了一条新的途径。然后，我们尝试从用上述方法得到的巨团簇溶液中制备新的巨团簇化合物。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。用单晶X射线衍射法测定了其中部分化合物的晶体结构。测定结果表明，存在一种新的空位类型的{Mo154}团簇，具有椭圆扭曲。这一发现可能对使用巨型团簇物种作为构建块的材料结构具有重要意义。此外，我们试图将巨型团簇的无定形特性应用于制备成分可控的均匀混合物，这些混合物适合作为低温合成的起始原料。我们可以证实，由巨团簇溶液制备的无定形混合物在较低的温度下提供了各种功能材料。

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.