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

本提案的重点是提供一系列裸阴离子金属离子和团簇在溶液中的行为的详细研究，并利用它们作为合成子对新的纳米团簇和分子合金的分离。尽管存在与样品纯度和/或分散性相关的问题，但溶液中阳离子金属物种的受控还原经常被用作合成新型金属团簇和纳米颗粒的途径。有趣的是，一种涉及溶液中带负电的金属氧化的相反方法尚未被开发为簇和纳米颗粒合成的过程。这些阴离子可以通过在存在碱金属的溶剂中直接溶解某些元素，如液氨或乙二胺，或者通过在固态中高温合成的预成形前驱体合金的溶解来获得。我们的研究将集中在一系列这样的阴离子的溶液反应性，即阴离子金、银、铂化铯和14、15基团的锌离子。我们设想，这些物种与过渡金属试剂和后过渡金属和主基团有机金属化合物的控制氧化将产生丰富的新的纳米团簇物种。对这些物种的兴趣是由于我们目前对化学键的理解的尺寸限制而产生的。随着团簇核的增加（n bbb12）和团簇形状偏离球形几何形状，经常发现这些物质在缺乏电子的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键合的因素，并随后发展新的理论来解释这种系统的奇异性，那么对更大范围的大型类金属团簇进行系统的表征是必要的。

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.