New insight into the electronic shell of Au38(SR)24: a superatomic molecule

Abstract

Based on the recently proposed super valence bond model, in which superatoms can compose superatomic molecules by sharing valence pairs and nuclei for shell closure, the 23c-14e bi-icosahedral Au(23)((+9)) core of Au(38)(SR)(24) is proved to be a superatomic molecule. Molecular orbital analysis reveals that the Au(23)((+9)) core is an exact analogue of the F(2) molecule in electronic configuration. Chemical bonding analysis by the adaptive natural density partitioning method confirms the superatomic molecule bonding framework of Au(38)(SR)(24) in a straightforward manner.

Au13(8e): A secondary block for describing a special group of liganded gold clusters containing icosahedral Au13 motifs

“…[20] In 2008, Walter and Hä kkinen et al proposed the superatom complex (SAC) model to explain high stabilities of some spherical ligand-protected Au nanoclusters with total count of valence electrons of 2,8,18,34,58 (electronic shell closing) on basis of the jellium model. [21] Later, Cheng et al developed a super valence bond (SVB) model [22] and a superatom network (SAN) model [23] to interpret high stabilities of certain nonspherical thiolate-protected Au nanoclusters based on the adaptive natural density partitioning (AdNDP) analysis. [24] A key concept in SAN model is that the core of Au nanoclusters can be viewed as a network of n-centered two-electron (n = 2-6) superatoms, originally developed to describe some small-sized Au clusters by Sergeeva and Boldyrev.…”

Luminescent gold nanoclusters as biocompatible probes for optical imaging and theranostics

“…[97] In particular, core size of most stable clusters observed in solution, in general, does not correspond to "magic numbers" predicted for ligand-free gas phase clusters and it does not consider the effect of clusters ligands on clusters stability and properties. [57,60,61,98,99] These drawback have been partially overcome by more recent computational methods based on new approaches, including the "superatom complex", [22,100,101] the Super Valence Bond (SVB) [102][103][104][105][106] and the superatom- [101,107] models, that have been developed to describe clusters electronic structures, both in gas and in solution phase. [22,37,41,42,93,95,99,100,104,[108][109][110][111][112][113][114] …”

Superatom Networks in Thiolate‐Protected Gold Nanoparticles

“…Using the SVB model, the 23-center 14-electron (23c-14e) bi-icosahedral Au core of [Au 38 (SR) 24 ] is shown to be a superatomic molecule (super F 2 ) in electronic shells. [28] Exceptions were also found for some other clusters such as [Au 18 (SR) 14 ], [Au 20 (SR) 16 ], and [Au 24 (SR) 20 ]. [10][11][12] The three compounds have both four free valence electrons in the gold core, which disagrees with the counts of magic numbers in the superatom model, but are electronically very stable with large HOMO-LUMO gaps in about 1.6 eV, 2.1 eV, and 1.5 eV, respectively.…”

“…Besides the four crystallized Au-SR compounds, there are also a variety of Au-SR compounds which are experimentally isolated and measured by mass and/or optical spectra but not crystallized yet, such as [Au 44 (SR) 28 ] 2À , [7] [Au 144 (SR) 60 ], [8] [Au 12 (SR) 9 ] + , [9] [Au 18 (SR) 14 ], [10] [Au 20 (SR) 16 ], [11] [Au 24 (SR) 20 ], [12] [Au 40 (SR) 24 ], [13] [Au 19 (SR) 13 ], [14] and [Au 68 (SR) 34 ]. [15] Structures of the experimentally isolated Au-SR compounds can be theoretically predicted by density functional theory (DFT) calculations.…”

“…[24] The total number of free valence electrons associated with a Au-SR cluster Au M (SR) N q can be counted based on the formula n* = MÀNÀq, where M is the number of Au(6s 1 ) electrons, N and q are the number of electron-withdrawing ligands (thiol groups) and the charge state of the cluster, respectively. Based on the superatom model, stability of the experimentally measured clusters can be understood with the magic numbers, such as [Au 102 (SR) 44 ] (58e), [2] [Au 68 (SR) 34 ] (34e), [15] [Au 44 (SR) 28 ] 2À (18e), [7] [Au 25 (SR) 18 ] À (8e), [4] and [Au 12 (SR) 9 ] + (2e). [9] These clusters both have a spherical and symmetric gold core.…”