Dr. James Espenson and Dr. Andreja Bakac of the Department of Chemistry, Iowa State University, are supported by the Inorganic, Bioinorganic, and Organometallic Program of the Chemistry Division for studies to develop a molecular level understanding of oxygen atom transfer. They will probe the mechanisms of oxygen atom transfer reactions of transition metal oxygen and oxo complexes. The studies include the use of the complex, methylrhenium dioxide (MDO), as a prototype oxygen atom acceptor, and inorganic oxyanions and transition metal oxo complexes as oxygen donors. Kinetic and thermodynamic determinations will be carried out to construct a scale of oxygen atom transfer reactivities on the basis of the Marcus equation. The effects of hydrogen bonding on the stability of superoxometal complexes will be studied using deuterium isotope effects, and the chemistry of superoxo and oxo ions of biologically relevant chromium complexes will be investigated. Chemical reactions in which oxygen atoms are transferred from one metal to another or from metals to non-metals are fundamental to many biological and industrial processes. However, advances in this area are currently hindered by the lack of a fundamental understanding of these processes. In this project, Espenson and Bakac will determine the rates and pathways by which oxygen is exchanged between various atoms, and they will relate these studies to the current theory which describes electron transfer reactions. They will explore oxygen transfer systems with industrial and biological relevance.
