Bonding of Two 8‐Electron Superatom Clusters

Abstract

We report the observation of dimerization of two 8electron superatom cluster units in the crystallographic structures of Au 2 Ag 42 (SAdm) 27 (BPh 4 )a nd [Au 2 Ag 48 (S-t Bu) 20 -(Dppm) 6 Br 11 ]Br(BPh 4 ) 2 nanoclusters.T he crystallographic analysis reveals that both nanoclusters have aA u 2 Ag 24 core made of two separated icosahedral without sharing metal atoms,and each icosahedron has an eight-electron (8e) closed shell (1S 2 1P 6 ). The valence electronic structures of these two nanoclusters are analogous to that of aN ea tom dimer (Ne 2 ) according to the density functional theory (DFT) analysis.This is the first crystallographic observation of the dimerization of 8-electron superatom units.This study enriches the fundamental knowledge on metal superatom clusters and implies the possibility for further assembling metal superatom building blocks into higher order superatom molecules.Metal clusters,w hich can be bare (in molecular beams) or ligated (in solid-state or solution phase), have attracted wide research interest. [1][2][3][4][5][6] Clusters such as sodium (Na n ), [7,8] aluminum (Al n ), [9][10][11] gold (Au n ), [12,13] and alloy clusters, [14,15] with certain numbers of atoms have been discovered to exhibit pronounced intensities in their mass spectra. Among these,t he "magic-sized" clusters with analogous valence electron configuration to atomic electron structure are regarded as superatoms,and ac losed-shell electronic configuration for such clusters in as phere model has been developed for understanding their extraordinary stability. [16][17][18] Further,several experimental and theoretical studies present that the superatom clusters can serve as the building block to form assemblies or compounds in combination with other atoms or superatom. [19][20][21][22][23] Ther esearch on the superatom-superatom interactions provide nanomaterials with new structure,s uperior bonding models,a nd various properties, promote the development of chemistry and materials science. [19][20][21][22][23][24][25] Thel igand-protected gold clusters having closed electronic shells are considered as superatoms owing to their noble-gas-atom-like valence electron configurations. [1] Several prototype gold superatom clusters,s uch as [Au 13 -(PMe 2 Ph) 10 Cl 2 ] 3+ (8e), [26] Au 39 (PR 3 ) 14 Cl 6 À (34e), [27] Au 25 -(SR) 18 À (8e) [28,29] and Au 102 (p-MBA) 44 (58e) [30] have been reported. Among nanoclusters,t he icosahedral metal cores which contain 8f ree valence electrons have been widely found in many gold/silver or doped superatom clusters such as [Au 13 (PMe 2 Ph) 10 Cl 2 ] 3+ , [26] MAu 24 (SR) 18 (M = Au/Pt/ Pd), [28,29,[31][32][33][34] MAg 24 (SR) 18 (M = Au/Ag/Pt/Pd), [35][36][37] [M 1 Ag 20 {S 2 P(OiPr) 2 } 12 ] + /[M 1 Ag 20 {Se 2 P(OEt) 2 } 12 ] + (M = Ag/ Au), [38,39] [M 1 Ag 19 {S 2 P(OR) 2 } 12 ]( M = Ag/Au), [40,41] [M 1 Ag 16 -(SR) 12 ] 3À . [42,43] In all known superatom and supermolecule clusters,t he 8e icosahedral superatom units typically share at least one metal atom when they form assembled str...

Insight into the Geometric and Electronic Structures of Gold/Silver Superatomic Clusters Based on Icosahedron M13 Units and Their Alloys

“…By comparing assembly methods for phosphine‐capped nanoclusters, more methods were observed for thiolated‐ or dual‐ligand‐capped supermolecules . The thiolated cluster obtained by superatomic M 13 assembly was Au 38 (SR) 24 .…”

“…), as a superatomic unit, has been reported for many years . As a building block, this unit can be assembled into different supramolecular structures by controlling the capping ligands . Different assembly forms of the M 13 unit not only contribute to the construction of superatomic aggregates with novel structures, but also have a remarkable effect on the optical, catalytic, and other properties of the superatomic aggregates .…”

“…Different assembly forms of the M 13 unit not only contribute to the construction of superatomic aggregates with novel structures, but also have a remarkable effect on the optical, catalytic, and other properties of the superatomic aggregates . This greatly encourages us to continue exploring the superatomic assembly of M 13 elements …”

“…In this review, we focus on gold/silver metal superatomic clusters based on the assembly of M 13 units, which have become a new class of nanomaterial and shown intriguing properties . Benefiting from single‐crystal X‐ray crystallography, the well‐determined structures have explicitly revealed the surface structure, the type of bonding, and the assembly method for nanoclusters consisting of M 13 units . We take some superatomic clusters as examples to present the geometric and electronic structures of superatomic clusters of gold/silver and clusters of their alloys based on M 13 units, such as [Au 13 Cl 2 (PR 3 ) 10 ] 3+ , Au 25 (SR) 18 − , Ag 25 (SR) 18 − Au 38 (SR) 24 and [Au 2 Ag 42 (SAdm) 27 ] + (SAdm=adamantanethiol .…”

“…Benefiting from single‐crystal X‐ray crystallography, the well‐determined structures have explicitly revealed the surface structure, the type of bonding, and the assembly method for nanoclusters consisting of M 13 units . We take some superatomic clusters as examples to present the geometric and electronic structures of superatomic clusters of gold/silver and clusters of their alloys based on M 13 units, such as [Au 13 Cl 2 (PR 3 ) 10 ] 3+ , Au 25 (SR) 18 − , Ag 25 (SR) 18 − Au 38 (SR) 24 and [Au 2 Ag 42 (SAdm) 27 ] + (SAdm=adamantanethiol . The insights gained will help to understand the metal superatomic cluster and provide a basis for specific applications through the regulation of assembly.…”