An alkynyl-protected Au40 nanocluster featuring PhCC–Au–P^P motifs

Abstract

An alkynyl-protected gold nanocluster [Au₄₀(PhCC)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 PhCC–Au–CCPh staple motifs are located around the central part of the Au₃₄ core, and four L-shaped PhCC–Au–P^P staple motifs are located at the four corners of the Au₃₄ core. Cluster 1 and [Au₃₈(PhCC)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.