New Perspectives on the Electronic and Geometric Structure of Au70S20(PPh3)12 Cluster: Superatomic-Network Core Protected by Novel Au12(µ3-S)10 Staple Motifs

Abstract

In order to increase the understanding of the recently synthesized Au70S20(PPh3)12 cluster, we used the divide and protect concept and superatom network model (SAN) to study the electronic and geometric of the cluster. According to the experimental coordinates of the cluster, the study of Au70S20(PPh3)12 cluster was carried out using density functional theory calculations. Based on the superatom complex (SAC) model, the number of the valence electrons of the cluster is 30. It is not the number of valence electrons satisfied for a magic cluster. According to the concept of divide and protect, Au70S20(PPh3)12 cluster can be viewed as Au-core protected by various staple motifs. On the basis of SAN model, the Au-core is composed of a union of 2e-superatoms, and 2e-superatoms can be Au3, Au4, Au5, or Au6. Au70S20(PPh3)12 cluster should contain fifteen 2e-superatoms on the basis of SAN model. On analyzing the chemical bonding features of Au70S20(PPh3)12, we showed that the electronic structure of it has a network of fifteen 2e-superatoms, abbreviated as 15 × 2e SAN. On the basis of the divide and protect concept, Au70S20(PPh3)12 cluster can be viewed as Au4616+[Au12(µ3-S)108−]2[PPh3]12. The Au4616+ core is composed of one Au2212+ innermost core and ten surrounding 2e-Au4 superatoms. The Au2212+ innermost core can either be viewed as a network of five 2e-Au6 superatoms, or be considered as a 10e-superatomic molecule. This new segmentation method can properly explain the structure and stability of Au70S20(PPh3)12 cluster. A novel extended staple motif [Au12(µ3-S)10]8− was discovered, which is a half-cage with ten µ3-S units and six teeth. The six teeth staple motif enriches the family of staple motifs in ligand-protected Au clusters. Au70S20(PPh3)12 cluster derives its stability from SAN model and aurophilic interactions. Inspired by the half-cage motif, we design three core-in-cage clusters with cage staple motifs, Cu6@Au12(μ3-S)8, Ag6@Au12(μ3-S)8 and Au6@Au12(μ3-S)8, which exhibit high thermostability and may be synthesized in future.

Density-functional tight-binding for phosphine-stabilized nanoscale gold clusters

“…Density functional theory (DFT) methods are most oen employed in theoretical investigations, as they are capable to accurately describe electronic, geometrical, and vibrational structure of gold clusters and nanoparticles. [16][17][18][19][20][21][22][23][24][25][26][27][28][29] In particular, the DFT-based simulation of IR, Raman, and UV-vis spectra has been achieved for a range of gold clusters, thus providing useful theoretical ngerprints to distinguish between bonding arrangements and orientations between gold atoms and ligands, and ligandligand interactions within clusters. 23,[30][31][32][33][34] Unfortunately, DFT calculations can become prohibitively expensive with system size, 35 and routine theoretical investigations are limited to moderate system sizes.…”

“…triphenylphosphine (PPh 3 ) is replaced by phosphine (PH 3 ) or trimethylphosphine (PMe 3 ). 17,18,22,25,26,28,29,36 This, as with the complete ligand removal approach, has the additional benet that conformational searching is simplied, as the torsions of the three phenyl groups per ligand give rise to a large number of local minima with similar energies. Nevertheless, it is well known that the electronic effects of the larger ligands are different from those of the smaller ones, for instance inductive effects, [36][37][38][39] and a computational truncation of the ligands will inuence the chemistry and therefore description of the catalytic properties in calculations.…”

Supramolecular Gold Chemistry: From Atomically Precise Thiolate-Protected Gold Nanoclusters to Gold-Thiolate Nanostructures

“…The aim of this Special Issue on "Supramolecular Gold Chemistry" was to provide a unique international forum aimed at covering a broad description of results involving the supramolecular chemistry of gold with a special focus on the gold-sulfur interface leading to hybrid materials, ranging from gold-thiolate complexes, [3] to thiolate-protected gold nanoclusters [4][5][6][7][8][9][10][11] and gold-thiolate supramolecular assemblies or nanoparticles. [12][13][14] The role of thiolates on the structure and optical features of gold nanohybrid systems (ranging from plasmonic gold nanoparticles and fluorescent gold nanoclusters to self-assembled Au-containing thiolated coordination polymers) has been highlighted in the review article by Csapó and coworkers [14].…”

“…Cheng and coworkers theoretically investigate Au 70 S 20 (PPh 3 ) 12 using density functional theory calculations. The electronic and geometric structure of Au 70 S 20 (PPh 3 ) 12 is further addressed based on the popular divide and protect concept and the superatom network model [7].…”

Metalloid gold clusters – past, current and future aspects

“…Cheng and coworkers also performed quantum chemical calculations on Au70 and showed that Au70 might be described via a superatom 133 network model exhibiting 2e-Au 4 superatoms. 134 In much broader studies Zhou et al and Cheng et al showed the important impacts of the Au 4 motif onto the structures of metalloid Au clusters. 135,136 …”