Dr. Michael T. Ashby, Department of Chemistry, University of Oklahoma, is supported by the Inorganic, Bioinorganic, and Organometallic Program of the Chemistry Division for a study of metal complexes containing ligands that are geometrically constrained so that they cannot donate pi electrons to the metal. Because their orientation precludes them from utilizing their maximum number of electrons in bonding with the metal, these ligands are termed `misdirected.` The project will address the fundamental questions of how can a ligand be `misdirected,` but still be firmly attached to a metal; the effects of `misdirected` ligands on the ground-state and transient properties of transition metal complexes; and the possibility that ligand `misdirection` and `redirection` can have practical application. To address these questions a series of complexes will be synthesized utilizing ligands that can be forced to shuttle between a conformation that allows pi interaction with the metal and one that is `misdirected.` The dynamic conformational properties of these complexes will be studied and the influence of ligand `misdirection` on the chemical properties of the complexes will be assessed. Many chemical reactions carried out in the laboratory, in industry, and by biological systems involve the participation of metal ions. Much of the unique reactivity of the metals is a reflection of variations, during the course of reactions, in the number of electrons surrounding the metal. This project will probe fundamental questions of how complexes can be designed so that groups attached to metal ions can be forced to provide variable numbers of electrons. Systems will be studied to determine both how to obtain such compounds and how controlled alterations in the metal electron counts can change chemical reactivity. This will set the ground work both to understand existing processes and to rationally design new ones.
