Synthesis and Study of Non-Keukule Molecules

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This grant from the Organic Dynamics Program supports the continuing work of Professor Paul Dowd at the University of Pittsburgh. The research is directed to the synthesis of reactive intermediates which possess two unbonded electrons. The project will further characterize the electronic state of these biradicals. There is an interest in biradical intermediates, since they are involved in ferromagnetism and some biological processes. Dr. Dowd's research will provide a bridge between theory and experiment in the area of biradical chemistry. In one project, the electronic structure of tetramethyleneethane will be probed experimentally in a rigid molecule. Previous studies in flexible systems have suggested that this biradical is a triplet, while molecular orbital calculations indicate a singlet. The use of a rigid system here will allow for an adequate comparison to the molecular orbital calculations. Simple molecular orbital theory predicts that non-alternant biradicals will be ground state singlets, yet this has not been tested. As a test of this theory, these biradicals will be generated and studied by spectrocopic methods and chemical trapping. Two other biradical systems, semilocalized biradicals and methylenecyclobutanone biradical, are to be prepared and characterized as well. Since biradicals are important intermediates in several chemical reactions, this work should add to our ability to understand and predict the course of reactions.