Sigma Pi Interactions in Hydrocarbon Cation Radicals and SS Bonds

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With support from the Organic Dynamics Program, Dr. Nelsen will study the detailed mechanism of the reaction of alkene cation radicals with oxygen, and he will also investigate electronic interactions in compounds that contain sulfur-sulfur bonds. In the first part of this project, Dr. Nelsen will study carbon skeletal rearrangements that accompany the reaction of certain alkylated alkenes and dienes with ground state oxygen. These skeletal rearrangements cause some alkenes to produce five-membered ring peroxides in competition with four-membered rings. In the second part, experimental and theoretical studies will be performed that are designed to probe the influence of electronic effects on rotational barriers in compounds that contain S-S bonds. %%% A particularly fascinating group of peroxides, called "dioxetanes", have two carbons and two oxygens linked together in a four-membered ring. Dr. Nelsen has developed a new type of reaction in which dioxetanes are produced directly from ground-state oxygen and alkenes via an intermediate cation radical. His approach permits the synthesis of new dioxetanes that cannot be made by other, more traditional methods for preparing dioxetanes. In the first part of this project, Dr. Nelsen will study the detailed mechanism of this process. In the second part, experiments will be performed that are designed to clarify the mechanism by which electronic interactions in compounds that contain sulfur-sulfur (S-S) bonds affect their chemistry. Since the strength of the S-S bond has important consequences in biological systems, the results of this aspect of Dr. Nelsen's overall study may have impact upon drug design (in addition to their fundamental importance to physical-organic and theoretical chemistry).