Mechanistic Chemistry of Transition Metal Oxygen and Oxo Complexes

该奖项将支持爱荷华州立大学化学系的James H.Espenson博士和Andreja Bakac博士在过渡金属介导的氧化反应方面所做的工作。许多研究将探索超氧铬(III)离子，它在铬(II)与氧反应时迅速形成。为了确定氧结合模式，将对相关的水和大环铬、钨和钼的络合物进行表征。离子的氧自交换机制将用放射性标记方法确定。将研究Ru、Rh和Cr与其他过渡金属氧受体之间的氧转移反应。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-过氧基或金属-超氧基络合物有望被观察到作为中间体。形成的金属-氧络合物将进行各种反应，包括电子转移和氢提取。在对细节的深入研究中，许多过渡金属离子与氧、Espenson和BaKac的相互作用将决定氧与金属结合的方式、氧与其他金属交换的速率和途径，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具有重要工业意义的有机氧化反应中的作用，以及金属氧离子在生物体系中的作用。

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.