Hydrogen Migration Reaction in Reactive Organic and Organometallic Intermediates

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The mechanistic basis underlying intramolecular hydrogen migration reactions in reactive organic and organometallic intermediates will be studied. Low-temperature matrix isolation spectroscopy, low- temperature NMR spectroscopy, and time-resolved absorption spectroscopy will be used to establish rearrangement pathways and to characterize the reactive species. Organic carbenes, organic nitrenes, and certain coordinately unsaturated 16-electron organometallic intermediates comprise an isolobal class of electron-deficient reactive intermediates that will be studied. In the organometallic studies, low-temperature NMR will be used to follow the chemistry of reactive allyl hydride intermediates and the involvement of these species in alkene isomerization processes. Iron, Osmium, and Ruthenium metal atoms will be incorporated in the organometallic intermediates. In particular, studies will be directed to allylic C-H and beta C-H insertion reactions. In the organic studies, experiments will focus on direct observation of hydrogen migration reactions of carbenes and 1,4-biradicals by time-resolved spectroscopy. %%% This grant from the Organic Dynamics Program supports the work of Professor Robert J. McMahon at the University of Wisconsin. The details of how hydrogen atoms migrate in reactive electron- deficient organic and organometallic intermediates by intramolecular processes will be studied. These elusive intermediates will be studied at low temperatures by various spectroscopic methods in order to characterize the intermediates and individual steps in the overall reaction. The reactive intermediates that will be studied include carbenes (divalent carbon species), nitrenes (monovalent nitrogen species), and organometallic intermediates that have 16 electrons rather than the stable 18-electron complement about the metal atom. Iron, Osmium, and Ruthenium metal atoms will be incorporated in the organometallic intermediates.