An alkynyl-protected Au40 nanocluster featuring PhC≡C–Au–P^P motifs

An alkynyl-protected gold nanocluster [Au40(PhC≡C)20(dppm)4](SbF6)4 (dppm = bis(diphenylphosphino)methane) (1) has been synthesized. Single-crystal X-ray diffraction reveals that the cluster has a face-centered cubic (FCC) Au34 kernel that is made up of two Au20 units via sharing a rectangular face. Two linear PhC≡C–Au–C≡CPh staple motifs are located around the central part of the Au34 core, and four L-shaped PhC≡C–Au–P^P staple motifs are located at the four corners of the Au34 core. Cluster 1 and [Au38(PhC≡C)20(PPh3)4](CF3SO3)2 both have the FCC Au34 core, and it is found that the diphosphine ligands bringing two more Au atoms into the system have significant effects on the optical properties and stability of the clusters. The combination of a diphosphine ligand and an alkynyl ligand is helpful in generating new ligand-protected metal nanoclusters.