  Controlled organic functionalization of silicon surfaces as integral part of
semiconductor technology offers new perspectives for a wide range of
applications. The high reactivity of the silicon dangling bonds, however,
presents a major hindrance for the first basic reaction step of such a
functionalization, i.e., the chemoselective attachment of bifunctional organic
molecules on the pristine silicon surface. We overcome this problem by
employing cyclooctyne as the major building block of our strategy.
Functionalized cyclooctynes are shown to react on Si(001) selectively via the
strained cyclooctyne triple bond while leaving the side groups intact. The
achieved selectivity originates from the distinctly different adsorption
dynamics of the separate functionalities: A direct adsorption pathway is
demonstrated for cyclooctyne as opposed to the vast majority of other organic
functional groups. The latter ones react on Si(001) via a metastable
intermediate which makes them effectively unreactive in competition with the
direct pathway of cyclooctyne's strained triple bond.
