Ion-molecule reactions catalyzed by a single gold atom.

We report that Au atoms within van der Waals complexes serve as catalysts for the first time. This was observed in ionization-induced chemistry of 1,6-hexanediol-Au and 1,8-octanediol-Au complexes formed in superfluid helium nanodroplets, where the addition of Au atom(s) made C2H4 + the sole prominent product in dissociative reactions. Density functional theory (DFT) calculations showed that the Au atom significantly strengthens all of the C-C bonds and weakens the C-O bonds in the meantime, making the C-C bonds stronger than the two C-O bonds in the ionized complexes. This leads to a preferential cleavage of the C-O bonds and thus a strong catalytic effect of the Au atoms in the reactions.