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

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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.