The ligand protected gold cluster exhibitsdistinct structural pattern in contrast to the bare moieties. A most strikingfeature of ligand stabilized AuN is its high symmetricalAu-core. A big breakthrough was made recently by the crystallizations ofthiolate-protected gold cluster Au102(p-MBA)44 (pMBA= -SC7O2H5) and Au25(SR)18-,which are composed of highly symmetric cores and staple motifs (i.e. �RS-Au-RS-and �RS-Au-RS-Au-RS-). In this work, the core-structure of a newlysynthesized �magic cluster� Au20(SR)16 (R = -CH2CH2Ph)is predicted, using ab initio calculations and global-minimum searches. Thelowest-energy structure of Au20(SCH3)16 iscomposed of a prolate-shaped Au8-core and four level-3Au3(SR)4 staple motifs RS-Au-RS-Au-RS-Au-RS-). Thesimulated optical absorption spectra of the lowest-energy structures are ingood agreement with the measured spectrum. The Au20(SR)16cluster, with a low Au/SR ratio of 1.25:1, may represent a structural evolutionfrom core-free homoleptic clusters [Au(SR)]N to core-stackedclusters. 

Thiolate-protected Au20(SR)16
cluster: Prolate Au8 core with novel [Au3(SR)4]
staple motifs

239th National Meeting (2010)

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Thiolate-protected Au20(SR)16 cluster: Prolate Au8 core with novel [Au3(SR)4] staple motifs

Thiolate-protected Au₂₀(SR)₁₆ cluster: Prolate Au₈ core with novel [Au₃(SR)₄] staple motifs