ORGN 572 |
| Density functional theory calculations (UB3LYP/6-31G(d,p)) were used to predict the singlet-triplet state energy gaps (DEST) for several different kinds of electron-deficient reactive intermediates, including arylnitrenium ions (Ar-NH+), benzyl cations (Ar-CH2+), aryl silylenium ions (Ar-SiH2+), and aryl oxenium ions (Ar-O+). Substituting the meta positions of these electron-deficient species with pi donors stabilizes a p,p* triplet state with an electronic structure analogous to the non-Kekule diradical m-xylylene. This electronic state was confirmed by viewing the Kohn-Sham orbital distributions, the Mulliken (and NPA) atomic spin densities, and geometries for the triplet states of these species. In most cases, substituting the meta position of these electron-deficient intermediates with strong pi donors (e.g. NMe2) was sufficient to make this p,p* triplet state the predicted ground electronic state. Experimental work to confirm this prediction will be discussed. |
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Asymmetric Reactions, Heterocycles, Aromatics, Combinatorial, and Physical Organic Chemistry
8:00 PM-10:00 PM, Wednesday, 31 August 2005 Washington DC Convention Center -- Hall A, Poster
Division of Organic Chemistry |