Oligomeric Gold Clusters with Vertex-Sharing Bi- and Triicosahedral Structures

Abstract

We present density functional studies of the geometric and electronic structures of a gold cluster compound [Au 25 (PH 3 ) 10 (SCH 3 ) 5 Cl 2 ] 2+ . The cluster has a unique geometric structure consisting of two icosahedral Au 13 clusters bridged by methanethiolates sharing a vertex gold atom and terminated by chlorine atoms. This structure is very close to the biicosahedral gold cluster [Au 25 (PPh 3 ) 10 (SC 2 H 5 ) 5 Cl 2 ] 2+ reported in a recent experiment. We further demonstrate that a vertex-sharing triicosahedral gold cluster [Au 37 (PH 3 ) 10 (SCH 3 ) 10 Cl 2 ] + is also achieved through bridging with the methanethiolates. A comparison between the absorption spectra of the biand triicosahedral clusters shows that the new electronic levels due to each oligomeric structure appear sequentially, whereas other electronic properties remain almost unchanged compared to the individual icosahedral Au 13 cluster.

Toward an Atomic-Level Understanding of Size-Specific Properties of Protected and Stabilized Gold Clusters

“…The emergent absorption peak is a direct consequence of dimerization of the Au 13 units as supported by a recent theoretical study by Nobusada and Iwasa. 129 This absorption has been assigned to the optical transition from the HOMO to the LUMO, which are localized within five atoms of the central axis. The observed PL (yield µ10%) is also a consequence of dimerization.…”

A unified view of ligand-protected gold clusters as superatom complexes

“…We discuss the relevance of our findings with respect to identification of the precise compositions of other known allthiolate-protected gold clusters, as well as the importance of the atomic structure of the interface of the gold core and the goldthiolate shell in compounds 1 and 2 regarding the structure of the interface of the bulk Au(111) and the self-assembled monolayer (SAM). The theoretical concepts laid out here provide a solid background for further understanding of the distinct electrical, optical, and chemical properties of the stable monolayer-protected Au nanoclusters (MPCs) (18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30), which eventually can parallel the wealth of information gained from investigations of nanosized gold clusters in the gas phase (10,11,(31)(32)(33)(34)(35) and should facilitate engineering of nano-applications, made out of MPC building blocks, for catalysis, sensing, photonics, biolabeling, and molecular electronics.…”

Chemically Induced Magnetism in Atomically Precise Gold Clusters

“…It has been shown earlier, that following Mingos's electron counting rule, this cluster can be regarded as a dimer of a closed-shell, 8-electron system. [ 29,30 ] Based on this interpretation, the cluster can be expected to be diamagnetic. The curve for thiol-stabilized Au 25 clusters (red) shows a paramagnetic behavior with an experimentally observed saturation magnetic moment of μ B = 0.0516/cluster or μ B = 0.0020/Au atom.…”