Isolation and Total Structure Determination of an All-Alkynyl-Protected Gold Nanocluster Au 144 .

Total structure determination of a ligand-protected gold nanocluster, Au ₁₄₄ , has been successfully carried out. The composition of title nanocluster is Au ₁₄₄ (C≡CAr) ₆₀ (1; Ar=2-FC ₆ H ₄ -). The cluster 1 exhibits a quasi-spherical Russian doll-like architecture, comprising a Au ₅₄ two-shelled Mackay icosahedron (Au ₁₂ @Au ₄₂ ), which is further enclosed by a Au ₆₀ anti-Mackay icosahedral shell. The Au ₁₁₄ 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 ₁₄₄ , 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 ₁₄₄ , which had been long-pursued, but also provides an interesting example showing ligand effects on the optical properties of ligand protected metal nanoclusters.
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