EAGER: Molecular Rare-Earth Clusters in Reduced Oxidation States

该奖项是根据2009年《美国复苏和再投资法案》(公法111-5)提供资金的。该奖项提交给无机、生物无机和金属有机(IBO)计划，支持马里兰大学的布莱恩·艾希霍恩教授开展基础研究，以制备具有直接共价金属键的稀土原子(即La、Y、Gd)的分子簇。由于到目前为止还没有已知的此类化合物的例子，而且这种化学的发展将代表着无机和团簇科学的重大突破，该奖项是通过早期概念探索性研究(AGER)计划颁发的。艾希霍恩教授和他的团队使用一种独特的还原金属卤化物合成设备(施诺克尔反应堆)来制备稀土一卤化物和二卤化物的溶液。空间位阻的氨基和羧基配体被引入以促进低核度簇合物的形成，即La2和La4簇合物。在更高温度下的受控歧化反应正被用来产生具有高核度La核的更大的“类金属”团簇。目标f-块元素(即，Gd、Nd)被用来产生由f-电子直接耦合产生的高磁性团簇。这种磁性纳米团簇提供了对稀土元素直接金属-金属键性质的基本洞察，并可直接用作磁存储元件、磁性成像剂和有机转化催化剂。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). The award, as submitted to the Inorganic, Bioinorganic and Organometallic (IBO) program, supports work by Professor Bryan Eichhorn at the University of Maryland to carry out fundamental studies on the preparation of molecular clusters containing rare-earth atoms (i.e., La, Y, Gd) with direct, covalent metal-metal bonds. As there are no previous examples of such compounds known to date and the development of this chemistry will represent a major breakthrough in inorganic and cluster science, this award is made through the EArly-concept Grants for Exploratory Research (EAGER) Program. Professor Eichhorn and his group employ a unique, reduced metal halide synthesis device (the Schnockel reactor) to prepare solutions of the rare earth monohalides and dihalides. Sterically-encumbered amido and carboxylato ligands are incorporated to promote the formation of low-nuclearity clusters, i.e., La2 and La4 clusters. Controlled disproportionation reactions at higher temperatures are being used to generate larger "metalloid" clusters with high nuclearity La cores. The targeted f-block elements (i.e., Gd, Nd) are used to produce highly magnetic clusters resulting from direct coupling of f-electrons. Such magnetic nanoclusters provide fundamental insight into the nature of direct metal-metal bonding for rare-earth elements and could be directly applicable as magnetic storage components, magnetic imaging agents, and catalysts for organic transformations.