Mechanistic Chemistry of Transition Metal Oxygen and Oxo Complexes

无机，生物无机和有机金属项目的这个奖项将支持博士的工作。爱荷华州立大学化学系的James H. Espenson和Andreja Bakac，研究过渡金属介导的氧化反应。许多研究将探索超氧铬（III）离子，当Cr（II）与氧反应时，超氧铬（III）离子迅速形成。相关的水和大环配合物的Cr， W和Mo将被表征，以确定氧结合模式。离子的氧自交换机制将用放射性标记方法确定。Ru， Rh和Cr与其他过渡金属氧受体之间的氧转移反应将被研究。此外，还将研究其他低价过渡金属离子与氧的快速反应，并确定这些反应的机理。金属-氧、金属-过氧或金属-超氧配合物可能作为中间体被观察到。形成的金属-氧配合物的各种反应将进行，包括电子转移和氢的提取。在对一些过渡金属离子与氧相互作用的详细研究中，Espenson和Bakac将确定氧与金属结合的方式、氧与其他金属交换的速率和途径。以及金属-氧配合物对氧化或还原的敏感性。这些基本结果有望有助于理解过渡金属在工业上重要的有机氧化反应中的作用，以及金属-氧离子在生物系统中的作用。

This award in the Inorganic, Bioinorganic, and Organometallic Program will support work by Drs. James H. Espenson and Andreja Bakac of the Chemistry Department, Iowa State University, on transition metal-mediated oxidation reactions. Many of the studies will explore the superoxochromium(III) ion, which is quickly formed when Cr(II) reacts with oxygen. Related aqua and macrocyclic complexes of Cr, W, and Mo will be characterized in order to determine the oxygen binding mode. The mechanism of oxygen self-exchange of the ion will be determined using radioactive labeling methods. Oxygen transfer reactions between Ru, Rh, and Cr and other transition metal oxo acceptors will be studied. In addition, the very rapid reactions of other low-valent transition metal ions with oxygen will be investigated and the mechanism of those reactions determined. Metal-oxo, metal-peroxo, or metal-superoxo complexes might be expected to be observed as intermediates. Various reactions of the metal-oxo complexes formed will be undertaken, including electron transfer and hydrogen abstraction. %%% In this thorough investigation of the details the interaction of a number of transition metal ions with oxygen, Espenson and Bakac will determine the way oxygen binds to the metal, the rates and pathways by which oxygen is exchanged with other metals, and the susceptibility of the metal-oxo complexes to oxidation or reduction. The fundamental results are expected to be helpful in understanding the role of transition metals in organic oxidation reactions, which are industrially important, and of metal-oxo ions in biological systems.