Homoleptic alkynyl-protected gold nanoclusters with unusual compositions and structures.

We report two novel homoleptic alkynyl-protected gold nanoclusters, which were synthesized by direct reduction of AuC[triple bond, length as m-dash]CR. Single-crystal X-ray structural analysis reveals that they have compositions of Au42(C[triple bond, length as m-dash]CC6H4-2-CF3)22 (1) and Au50(C[triple bond, length as m-dash]C6H4-3-F)26 (2), respectively. Cluster 2 is the first Au50 nanocluster, and the metal-to-ligand ratios of 1 and 2 are different from those of known Aun(SR)m or Aux(C[triple bond, length as m-dash]CR)y nanoclusters. In addition, the metal kernels of these two clusters are built up unprecedented units. This work offers further insights into the synthesis of all-alkynyl-protected gold nanoclusters via a direct reduction method.