JACS Abstract

Abstract

A set of forty finite temperature ab initio molecular dynamics trajectories is employed to investigate the distribution of addition products and underlying microscopic mechanism of the addition of 1,3-butadiene to the Si(100)2x1 surface. The product yields are in good agreement with recent STM measurements and include a Diels-Alder [4+2] adduct with a surface dimer acting as the dienophile, a [4+2]-like adduct which bridges two dimers within a row, a [4+2]-like adduct which bridges two dimers in adjacent rows, and an interdimer [2+2] adduct. The trajectories indicate that a common mechanism underlies the distribution and is predominantly a non-concerted stepwise mechanism that proceeds via an intermediate zwitterion composed of a carbocation bonded to a negatively charged surface dimer.