Site-Selective Coordination Controls Chirality Transfer in an Atomically Precise Au8 Cluster

Atomically precise metal clusters possess multiple inequivalent coordination sites, enabling site-selective ligand coordination to regulate their structures and chiroptical properties. However, the impact of coordination site on chirality transfer remains poorly understood. Herein, we report the selective functionalization of an Au8 cluster by installing chiral ligands at two distinct coordination sites, generating two chiral clusters. Coordination of chiral bidentate phosphine ligands at the core-Au sites dramatically enhances the chiroptical response, whereas functionalization of the exo-Au sites with chiral alkynyl ligands produces only a weak effect. Time-dependent density functional theory calculations show that the core-Au coordinated chiral phosphine ligands induce more pronounced distortion of the Au8 framework than the exo-coordinated alkynyl ligands, thus enhancing the intensity of electronic circular dichroism transitions. This work highlights that the coordination site is a key factor in chirality transfer and chiroptical activity in atomically precise metal clusters.