This project titled "The Solvent Cage Effect in Organometallic Chemistry" will be carried out by Thomas W. Koenig and David R. Tyler of the University of Oregon and is funded within the Inorganic, Bioinorganic and Organometallic Chemistry Program. The research will examine the fate of organometallic radicals in a solvent cage. The results of this study are expected to lead to enhanced knowledge of the reactivity of organometallic radicals and thus a greater understanding of the mechanism by which many organometallic reactions occur. Studies will be carried out on cage radical pairs that are formed both reversibly and irreversibly from selected precursor molecules. The reversibly formed cage pairs will be generated by thermolysis of metal-metal or metal-carbon bonds, such as in octacarbonylbis(triphenylphosphine)dimanganese(0). The irreversibly formed cage pairs will be generated by photolysis of dimetallic complexes which eliminate an intervening atom or molecule, such as bis(tetracarbonylcobalt)mercury in which the mercury atom is eliminated as the small spacer molecule between the cobalt groups. Specific goals in addition to the increased understanding of radical reactivity are: determining substantially improved values of bond dissociation energies for organometallic complexes; determining the cage efficiency, i.e., cage combination compared to cage escape of radicals; and assessing the effects of steric size and mass of the radical as well as the viscosity of the solvent on the cage efficiency.
