Origin of Magic Stability of Thiolated Gold Clusters: A Case Study on Au25(SC6H13)18
The present work aims to test the validity of the electronic shell model for Au 25 (SC 6 H 13 ) 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 [Au 25 (SC 6 H 13 ) 18 ] x with a distribution of charge states, which shifts toward negative values with reduction time. The stable ions [Au 25 (SC 6 H 13 ) 18 ] 1+ and [Au 25 (SC 6 H 13 ) 18 ] 1- can be synthesized by chemical oxidation and reduction of [Au 25 (SC 6 H 13 ) 18 ] 0, respectively. These findings lead us to conclude that electronic shell closing is not a crucial factor for the high stability of [Au 25 (SC 6 H 13 ) 18 ] x ( x = 1−, 0, 1+). We ascribe magic stability to the core-in-cage structure predicted theoretically.