The focus of this project in the Inorganic, Bioinorganic and Organometallic Chemistry Program is the chemistry of compounds of main-group elements in aqueous solution. Main-group elements include sulfur, oxygen, chlorine, nitrogen and selenium, and the reactions of main-group compounds are involved in a variety of processes of great ecomomic and social importance, ranging from something as mundane as the action of chlorine bleach to the environmentally important formation of acid rain. The primary focus of this project is the oxidation and reduction of main-group compounds, especially through free radical intermediates. One set of reactions will use substitution-inert coordination compounds as the reaction partners, which will have the advantage of relatively predictable reaction mechanisms. Oxidation of sulfite by a Ru(III) complex will be used to estimate the standard redox potential of the sulfite radical, and is expected to demonstrate the novel process of free-radical sulfonation. This and studies with related complexes will be used to elucidate the factors affecting electron transfer at pyramidal molecules. Oxidation of NO by a Ni(III) complex will be studied to provide insight on the obscure phenomenon of nuclear tunneling. Nuclear tunneling will be probed further in studies of the outer-sphere reduction of BrCN and through kinetic isotope effects in the oxidations of nitrite ion and NO. The other class of reactions to be investigated is redox reactions between main-group molecules. The self-exchange rate for the dioxygen/superoxide couple will be measured directly. Other reactions in this class will probe the hypothesis that electron transfer between main-group species invariably proceeds with rates much greater than predicted by Marcus theory.
