Chemistry, Ames Laboratory
Journal or Book Title
Journal of the American Chemical Society
Multi-reference as well as single-reference quantum mechanical methods were adopted to study the potential energy surface along three possible surface reaction mechanisms of acrylonitrile on the Si(100)-2×1 surface. All three reactions occur via stepwise radical mechanisms. According to the computed potential energy surfaces, both [4+2] and [2+2]CNcycloaddition products resulting from the reactions of surface dimers with the C⋮N of acrylonitrile are expected, due to the negligible activation barriers at the surface. Another possible surface product, [2+2]CC, requires a 16.7 kcal/mol activation energy barrier. The large barrier makes this route much less favorable kinetically, even though this route produces the thermodynamically most stable products. Isomerization reactions among the surface products are very unlikely due to the predicted large activation barriers preventing thermal redistributions of the surface products. As a result, the distribution of the final surface products is kinetically controlled leading to a reinterpretation of recent experiments. An intermediate Lewis acid−base type complex appears in both the [4+2] and [2+2]CNcycloadditions entrance channels, indicating that the surface may act as an electrophile/Lewis acid toward a strong Lewis base substrate.
American Chemical Society
Choi, Cheol Ho and Gordon, Mark S., "Cycloaddition Reactions of Acrylonitrile on the Si(100)-2×1 Surface" (2002). Ames Laboratory Publications. 324.