Single Cu Atom Doping on Au_{11} Nanocluster: Its Implication towards Selectivity in C-C Coupling Reaction
S. Mukherjee, A. Das, A.K. Das, A. Sheriff, K. Sunny, A.S. Nair, S. Bhandary, R. Bhowal, D. Chopra, B. Pathak, S. Yamazoe, S. Mandal
Chem. Mater., accepted.
Atom precise metal nanoclusters with customized surface structures are important for understanding the mechanism of surface engineering and appropriate applications. We are reporting a single copper doping on a very widely studied Au_{11}(PPh_{3})_{7}Cl_{3} nanocluster, in which one chloride ligand replaced by one Cu atomic site. Accordingly, a new bimetal nanocluster Cu1Au_{11}(PPh_{3})_{7}Cl_{2} is produced, which consisted of a unique Au-Cu surface motif, where the Cu is only bonded with Au atom. In such a motif, unsaturated Cu atom act as an active catalyst for the Sonogashira reaction in contrast to the catalytically inactive Au_{11} nanocluster. Moreover, it demonstrated a reversed selectivity in the Sonogashira cross-coupling reaction, where the major product obtained was homo-coupled Glaser products in contrast to the selectivity of previously reported cluster/bimetallic clusters towards Ullmann or Sonogashira products. Theoretical calculations support that the unsaturated Cu to be the active site on the NC and acting like a single-atom catalyst. This highlights the effect of mono copper atom doping on the unique selectivity in Sonogashira cross-coupling reaction.