Eur. Phys. J. D 63, 311-314 (2011)
https://doi.org/10.1140/epjd/e2011-10603-9

Regular Article

Derivatives of the thiolate-protected gold cluster Au₂₅(SR)₁₈^-1

Department of Physics and Department of Chemistry, Nanoscience Center, University of Jyväskylä, 40014 Jyväskylä, Finland

^a e-mail: lopez@cc.jyu.fi

Received: 20 October 2010
Received in final form: 21 December 2010
Published online: 27 April 2011

Abstract

Loss of small fragments (like AuL, Au₂L₃, Au₄L₄) have been found systematically in several MALDI and FAB experiments on thiolate-protected gold clusters of different sizes. When using the cluster Au₂₅L₁₈^-1 as parent cluster, the fragmented cluster Au₂₁L₁₄^-1 has been reported to be obtained in high proportion (L = SCH₂CH₂Ph). Here we analyse a few possible fragmentation patterns of the well-known parent cluster Au₂₅L₁₈^-1 (L = SCH₃). Using DFT calculations we study the different atomic configurations obtained after a AuL fragment is lost from Au₂₅L₁₈^-1. We found energetically favourable configurations that can be written as Au₁₃ [Au₂L₃]_6-z[AuL₂]_z^-1, where the modification can be described as a replacement of the long protecting unit by a short one (Au₂L₃  →  AuL₂). A full replacement (z = 6) gives rise to a protected Au₁₉L₁₂^-1 cluster. This mechanism does not modify the super-atomic electronic structure of the gold core, i.e., all these fragments remain an 8 electron super-atom clusters exactly like the parent Au₂₅L₁₈^-1. We suggest that the Au₁₉L₁₂^-1 cluster could be realized by using a bulky thiolate, such as the tert-butyl thiolate SC(CH₃)₃ .