Organometallic compounds are frequently used as catalysts for the conversion of one organic compound into another. Unfortunately, such conversions often result in mixtures of isomers, i.e., molecules comprised of the same atoms, but differing in their three-dimensional structures. This project involves the synthesis of highly unsymmetrical organometallic compounds designed to function as more specific catalysts to control the three-dimensional structures of reaction products. The three- dimensional structures of organic molecules are especially important in biological reactions, and these organometallic compounds are often used in the laboratory synthesis of natural products. Research will be undertaken to develop new methods using metal complexes for asymmetric and regioselective syntheses and to elucidate the mechanisms of stereoselective reactions which are synthetically useful. The potential utility of higher oxidation state organometallic complexes for these applications will be explored. X-ray crystallography has become a routine tool for structural characterization in solids. However, many organometallic compounds rearrange or exist as mixtures of conformational isomers in solution. It has been shown in this laboratory that the stability of these conformers plays a major role in the distribution of product stereochemistry. Reactive intermediates and catalytic species often exist in lower concentrations and cannot be isolated as solids. A new method will be developed to elucidate detailed structural information in solution. This will involve the design and synthesis of ligands containing paramagnetic metal ions which bind to organometallics. The isotropic shifts and the effects of field alignment produced by these paramagnetic ligands will allow detailed delineation (angles and distances) of intermediates and catalytic species in solution.
