title: Thiolate-protected Au20(SR)16 cluster: prolate Au8 core with new [Au3(SR)4] staple motif.
abstract: The precise atomic structure of the recently synthesized "magic cluster" Au(20)(SR)(16) is predicted using ab initio calculations and global-minimum searches. The cluster contains a prolate Au(8) core and four level-3 extended staple motifs (-RS-Au-RS-Au-RS-Au-RS-). The simulated optical absorption spectra of the lowest-energy structures are in good agreement with the measured spectrum. The Au(20)(SR)(16) cluster, with a low Au/SR ratio of 1.25:1, may represent a structural evolution from core-free homoleptic clusters [Au(SR)](N) to core-stacked clusters.
authors.affiliation: Department of Chemistry and Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, USA.
authors.forename: Yong
authors.initials: Y
authors.lastname: Pei
authors.forename: Yi
authors.initials: Y
authors.lastname: Gao
authors.forename: Nan
authors.initials: N
authors.lastname: Shao
authors.forename: Xiao Cheng
authors.initials: XC
authors.lastname: Zeng