Synthesis of novel nanometric clusters by controlled oxidation of negatively-charged metal species

这项提议的重点是提供一系列裸露的阴离子金属离子和团簇在溶液中的行为的详细研究，并将它们用作合成子来分离新的纳米团簇和分子合金。尽管存在与样品纯度和分散性有关的问题，但控制还原溶液中的阳离子金属物种经常被用作合成新型金属簇合物和纳米颗粒的方法。有趣的是，一种相反的方法，包括溶液中带负电荷的金属物种的氧化，还没有被用作团簇和纳米粒子合成的过程。这些阴离子物种可以通过在有碱金属存在的情况下将某些元素直接溶解在液氨或乙二胺等溶剂中来获得，或者通过将在高温下合成的预制前体合金在固态中溶解来获得。我们的研究将集中在一系列这样的阴离子物种的溶液反应性上，即阴离子金和银，铯铂化物和第14和15族的锌离子。我们设想用过渡金属试剂和后过渡金属和主族有机金属控制氧化这些物种将产生丰富的新的纳米簇合物物种。对这类物种的兴趣源于目前我们对化学键的理解的大小限制。随着团簇成核度的增加(n&gt；12)和团簇形状偏离球状几何形状，人们经常发现这些物种在缺电子团簇中不遵守传统的成键规则。如果我们要在纳米尺度上理解控制成键的因素，并随后发展新的理论来解释这种体系的奇异性，那么对更大范围的大类金属团簇的系统表征是必要的。

The focus of this proposal is to provide a detailed study of the behaviour of a series of naked anionic metal ions and clusters in solution and to employ them as synthons towards the isolation of novel nanometric clusters and molecular alloys. Controlled reduction of cationic metal species in solution is frequently employed as a route towards the synthesis of novel metal clusters and nanoparticles despite suffering from problems associated with sample purity and/or dispersity. Interestingly, an inverse approach, involving the oxidation of negatively-charged metal species in solution has yet to be exploited as a course towards cluster and nanoparticle synthesis. These anionic species can be obtained by direct dissolution of certain elements in solvents such as liquid ammonia or ethylenediamine in the presence of alkali metals, or alternatively by dissolution of preformed precursor alloys synthesized at high-temperature in the solid-state. Our research will focus on the solution reactivity of a series of such anionic species, namely anionic gold and silver, cesium platinide and the Zintl ions of groups 14 and 15. We envision that controlled oxidation of these species with transition metal reagents and post-transition metal and main-group organometallics will yield a wealth of new nanometric cluster species. The interest in such species arises due to the current size-limitation of our understanding of chemical bonding. As cluster nuclearity increases (n>12) and cluster shapes deviate from spherical geometries it is often found that such species fail to obey traditional rules for bonding in electron-deficient clusters. The systematic characterization of a greater breadth of large metalloid clusters is necessary if we are to form an understanding of the factors governing bonding at the nanometric scale and subsequently develop novel theories in order to account for the singularity of such systems.