Isolation and Total Structure Determination of an All-Alkynyl-Protected Gold Nanocluster Au.

Total structure determination of a ligand-protected gold nanocluster, Au , has been successfully carried out. The composition of title nanocluster is Au (C≡CAr) (1; Ar=2-FC H -). The cluster 1 exhibits a quasi-spherical Russian doll-like architecture, comprising a Au two-shelled Mackay icosahedron (Au @Au ), which is further enclosed by a Au anti-Mackay icosahedral shell. The Au kernel is enwrapped by thirty linear ArC≡C-Au-C≡CAr staple motifs. The absorption spectrum of 1 shows two bands at 560 and 620 nm. This spectrum is distinctly different from that of thiolated Au , which was predicted to have an almost identical metal kernel and very similar ligands arrangement in 1. These facts indicate the molecule-like behavior of 1 and significant involvement of ligands in the electronic structure of 1. The cluster 1 is hitherto the largest coinage metal nanocluster with atomically precise molecular structure in the alkynyl family. The work not only addresses the concern of structural information of Au , which had been long-pursued, but also provides an interesting example showing ligand effects on the optical properties of ligand protected metal nanoclusters.