Origin of Magic Stability of Thiolated Gold Clusters: A Case Study on Au₂₅(SC₆H₁₃)₁₈

Abstract

The present work aims to test the validity of the electronic shell model for Au25(SC6H13)18 by monitoring the charge state of the Au:S core and thereby to elucidate the origin of magic stability. Electrospray ionization mass spectrometry revealed that the Schiffrin method yields [Au25(SC6H13)18]x with a distribution of charge states, which shifts toward negative values with reduction time. The stable ions [Au25(SC6H13)18]1+ and [Au25(SC6H13)18]1- can be synthesized by chemical oxidation and reduction of [Au25(SC6H13)18]0, respectively. These findings lead us to conclude that electronic shell closing is not a crucial factor for the high stability of [Au25(SC6H13)18]x (x = 1−, 0, 1+). We ascribe magic stability to the core-in-cage structure predicted theoretically.