Cycloaddition reactions of dienes on the Si(100)-2X1 surface

Quantum mechanical methods were adopted to study the surface reaction mechanisms of 1,3-cyclohexadiene and acrylonitrile on the Si(100)-2x1 surface. According to the computed potential energy surfaces, both [4+2] and [2+2] cycloaddition products resulting from the reactions of surface dimers are possible due to the negligible activation barriers at the surface. 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] cycloadditions of acrylonitrile entrance channels, indicating that the surface may act as an electrophile/Lewis acid towards a strong Lewis base substrate.