Single Cu Atom Doping on Au₁₁ Nanocluster: Its Implication toward Selectivity in C–C Coupling Reaction

Abstract

Atom precise metal nanoclusters with customized surface structures are important for understanding the mechanism of surface engineering for appropriate applications. We are reporting a single copper doping on a very widely studied Au11(PPh3)7Cl3 nanocluster, in which one chloride ligand is replaced by one Cu atom. Accordingly, a new bimetal nanocluster Cu1Au11(PPh3)7Cl2 is produced, which consisted of a unique Au–Cu surface motif where the Cu is only bonded with an Au atom. In such a motif, the unsaturated Cu atom acts as an active catalyst for the Sonogashira reaction in contrast to the catalytically inactive Au11 nanocluster. Moreover, it demonstrated a reversed selectivity in the Sonogashira cross-coupling reaction, where the major product obtained was homocoupled Glaser products in contrast to the selectivity of previously reported cluster/bimetallic clusters toward Ullmann or Sonogashira products. Theoretical calculations support the unsaturated Cu to be the active site on the nanocluster (NC) and act like a single-atom catalyst. This highlights the effect of mono copper atom doping on the unique selectivity in the Sonogashira cross-coupling reaction.