9314894 Platz The generation of carbenes by photochemical methods and reactions of these transient intermediates will be studied. Experiments will be carried out to provide fundamental information about the geometry, singlet/triplet energy levels, heats of formation, and rates of intra-and intermolecular reactions of carbenes. An emphasis will placed on understanding the rearrangement of alkyl carbenes, where low activation enthalpies and large negative entropies of activation have been observed. In particular, the possibility of tunneling as an explanation for the unusual activation parameters will be pursued. The chemistry of excited state diazirines will be studied in detail, since these precursors to carbenes may mimic some of the chemistry of carbenes. Several points along the reaction surface will be characterized for the reaction of excited state diazirines. %%% This grant from the Organic Dynamics Program supports the continuing work of Professor Matthew S. Platz at Ohio State University. Carbenes are high energy compounds which contain only two bonds to other elements from carbon, while stable compounds of carbon contain four bonds to other elements. In a large number of reactions, carbene intermediates are generated. The lifetimes of these fleeting intermediates will be determined as a function of structure of the carbene, solvent polarity, and temperature. These studies will lead to a basic understanding of these important intermediates and to their use in synthesis. ***
