Electronic Structure and Optical Properties of the Thiolate-Protected Au28(SMe)20 Cluster

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Vol. 117; no. 40; pp. 10526 - 10533
• Main Authors: Knoppe, Stefan, Malola, Sami, Lehtovaara, Lauri, Bürgi, Thomas, Häkkinen, Hannu
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 10.10.2013
• Subjects: Atomic and molecular physics; Calculations and mathematical techniques in atomic and molecular physics (excluding electron correlation calculations); Density-functional theory; Electronic structure of atoms, molecules and their ions: theory; Exact sciences and technology; Physics; Theoretical study; Density functional method; Electronic structure; Optical properties; Optical absorption; Circular dichroism
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/jp407494v

The recently reported crystal structure of the Au28(TBBT)20 cluster (TBBT: p-tert-butylbenzenethiolate) is analyzed with (time-dependent) density functional theory (TD-DFT). Bader charge analysis reveals a novel trimeric Au3(SR)4 binding motif. The cluster can be formulated as Au14(Au2(SR)3)4(Au3(SR)4)2. The electronic structure of the Au14 6+ core and the ligand-protected cluster were analyzed, and their stability can be explained by formation of distorted eight-electron superatoms. Optical absorption and circular dichroism (CD) spectra were calculated and compared to the experiment. Assignment of handedness of the intrinsically chiral cluster is possible.