Au57 Ag53 (C≡CPh)40 Br12 : A Large Nanocluster with C1 Symmetry.

The controlled synthesis and structure determination of a bimetallic nanocluster Au57 Ag53 (C≡CPh)40 Br12 (Au57 Ag53 ) is presented. The metal core has a four-shell Au2 M3 @Au34 @Ag51 @Au20 (M=1/3 Au+2/3 Ag) architecture. In contrast to the previously reported large nanoclusters that have highly symmetric kernel structures, the metal atoms in Au57 Ag53 are arranged in an irregular manner with C1 symmetry. This cluster exhibits excellent thermal stability and is robust under oxidative or basic conditions. The silver precursors play a key role in dictating the structures of the nanoclusters, which suggests the importance of the counteranions used.