EXCITED STATE GEOMETRY OF BENZIL
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Date
1978
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Publisher
Ohio State University
Abstract
Geometry of benzil in its lower excited states is known to be different from that of the ground state. Indeed there are speculations that the dicarbonyl fragment of benzil is actually trans-planar in the triplet $state^{1}$ We have undertaken a systematic ENDOR study of the molecule in order to determine its precise geometry In the lowest triplet. ENDOR transitions of both the ring protons and the $^{13}C$’s in the dicarbonyl fragment have been utilized. The chemical shift of the protons are relatively small, implying a small delocalization of the excited electron into the rings. The two $^{13}C$ hyperfine tensors have different principal axes. This observation excludes the possibility that the dicarbonyl fragment is trans-planar, as previously suggested. A quantitative model for the geometry and spin distribution of triplet state benzil will be discussed.
Description
$^{1}$ J. F. Arnett and S. P. McGlynn, J. Phys. Chem., 79, 626 (1975); I. Y. Chan and B. N. Nelson, J. Chem Phys., 62, 4080 (1975). Present address of Barbara A. Heath: Bell Telephone Labs, Murray Hill, New Jersey, 07974""
Author Institution: Department of Chemistry, Brandeis University
Author Institution: Department of Chemistry, Brandeis University