David Rohrabacher of Wayne State University and Michael Taschner of the University of Akron are supported by the Inorganic, Bioinorganic, and Organometallic Chemistry Program for research on effects of coordination site geometry on rates of electron transfer reactions of cuprous (Cu(I)) and cupric (Cu(II)) complexes. The main focus of the research will be to explore how ligands that constrain geometry about one or both copper centers influence the kinetics and mechanism of electron transfer (ET) between the two copper atoms. Main interest will be on the influence of solvent molecules on the ET rates of complexes involving macrocyclic and tripodal ligands, effects of trigonal and trigonal-pyramidal ligands that mimic coordination sites in specific copper proteins, and reorganization barriers in metastable intermediate species in reactions that involve macrocyclic ligands. Electron transfer reactions in related complexes containing both ruthenium and copper will also be investigated. New ligands to be used in each of these research areas will be synthesized at The University of Akron. Kinetic, electrochemical and spectroscopic studies will be performed at Wayne State University.
Electron transfer reactions involving transition metal ions are of central importance in many areas of industrial chemistry and biochemistry and also in the emerging field of molecular electronics. This study focuses on rate processes that are known to be controlled, in greater or less degree, by conformational changes in the first coordination shells of the metal ions. This type of process has also been identified (sometimes quite tentatively) as playing a major role in many more-complex systems of practical interest. The relatively uncomplicated cases that are studied in this project are exceptionally suitable for developing and testing understandings that can then be applied to the more complicated cases that are of central importance in biological and technological applications.
