Diradical mechanism for the [2 + 2] cycloaddition of ethylene on Si(100) surface

A study showed that by means of density functional cluster model calculations, the adsorption of ethylene on Si(100) surface follows a diradical mechanism, proceeding visa pai-complex precursor and a singlet diradical intermediate. The calculations confirmed the scanning tunneling microscopy (STM) observation that the adsorption of an alkene on Si(100) is not stereospecific but highly stereoselective in nature.