A Chiral Gold Nanocluster Au20 Protected by Tetradentate Phosphine Ligands

The chirality of a gold nanocluster can be generated from either an intrinsically chiral inorganic core or an achiral inorganic core in a chiral environment. The first structural determination of a gold nanocluster containing an intrinsic chiral inorganic core is reported. The chiral gold nanocluster [Au-20(PP3)(4)]Cl-4 (PP3=tris(2-(diphenylphosphino)ethyl)phosphine) has been prepared by the reduction of a gold(I)-tetraphosphine precursor in dichloromethane solution. Single-crystal structural determination reveals that the cluster molecular structure has C-3 symmetry. It consists of a Au-20 core consolidated by four peripheral tetraphosphines. The Au-20 core can be viewed as the combination of an icosahedral Au-13 and a helical Y-shaped Au-7 motif. The identity of this Au-20 cluster is confirmed by ESI-MS. The chelation of multidentate phosphines enhances the stability of this Au-20 cluster.