Structural dynamics of molecular rearrangement in the NO release from nitrobenzene determined by ultrafast electron diffraction

PHYS 411

Yonggang He, hey@caltech.edu, Andreas Gahlmann, agahlman@caltech.edu, Jonathan S. Feenstra, Sang Tae Park, and Ahmed H. Zewail, zewail@caltech.edu. Department of Chemistry, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125
Nitro compounds release NO, NO2, and other species, but neither the structures during the reactions nor the time scales are known. Here, using ultrafast electron diffraction (UED), we provide our first study of the NO release from nitrobenzene. We determine the molecular pathways and the structures of transient species therein. It is observed, contrary to previous inferences, that nitric oxide and phenoxyl radicals are formed dominantly and that the time scale of formation is 8.8 2.2 ps. The structure of the phenoxyl radical is determined for the first time, and found to be quinoid-like. The mechanism proposed here involves a repulsive triplet-state, following intramolecular rearrangement. This efficient generation of NO may have important implications for the control of by-products in drug delivery and other applications.
 

Poster Session
7:30 PM-10:00 PM, Wednesday, 13 September 2006 Moscone Center -- Hall D, Poster

Sci-Mix
8:00 PM-10:00 PM, Monday, 11 September 2006 Moscone Center -- Hall D, Sci-Mix

Division of Physical Chemistry

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006