Alkynyl-Protected Chiral Bimetallic Ag Cu Superatom with Multiple Chirality Origins.

Understanding the origin of chirality in the nanostructured materials is essential for chiroptical and catalytic applications. Here we report a chiral AgCu superatomic cluster, [Ag Cu (C≡CR) (PPh ) Cl ](PPh ), Ag Cu , protected by an achiral alkynyl ligand (HC≡CR: 3,5-bis(trifluoromethyl)phenylacetylene). Its crystal structure comprises a rare interpenetrating biicosahedral Ag Cu core, which is stabilized by four different types of motifs: one Cu(C≡CR) , four -C≡CR, two chlorides and one helical Ag Cu (C≡CR) (PPh ) Cl . Structural analysis reveals that Ag Cu exhibits multiple chirality origins, including the metal core, the metal-ligand interface and the ligand layer. Furthermore, the circular dichroism spectra of R/S-Ag Cu are obtained by employing appropriate chiral molecules as optical enrichment agents. DFT calculations show that Ag Cu is an eight-electron superatom, confirm that the cluster is chirally active, and help to analyze the origins of the circular dichroism.