A Chemical View of the Giant Au₁₀₂(SR)₄₄ (SR = P‐Mercaptobenzoic Acid) Cluster: Metalloid Aluminum and Gallium Clusters as Path Making Examples of This Novel Type Open Our Eyes for Structure and Bonding of Metalloid Au_n(SR)_m (n > m) Clusters

Abstract

The outstanding position of metalloid clusters as intermediates between the bulk metals and bulk salts on the one hand and of naked metal atom clusters and salt-like clusters on the other hand is described first. Subsequently, a different more chemical description of structure and bonding of a recently published gold-thiolate Au 102 (SR) 44 cluster based on the results of aluminum-/gallium clusters is presented. This comparison shows that there is no principal but only a gradual difference between the Au 102 cluster and the large number of metalloid aluminum-/gallium clusters: both have a metalloid character, i.e. there is a highly mixed valent bonding situation of the metal atoms involved. Therefore these clusters represent a highly complex system and are far from being only nanoscaled metal particles surrounded by a shell of protecting ligands. In detail this comparison shows that the metalloid gold and the aluminum-/gallium clusters are similar in the center, as these metal-metal interactions are energetically similar to those of the

Structure, Thermodynamics, and Energy Content of Aluminum–Cyclopentadienyl Clusters

“…Very recent work by Schn€ ockel and co-workers provides some additional discussion on the asymmetry of the Al 8 core in relation to recently synthesized organometallic gold clusters. 30 We next consider in more detail the nature of the metalÀ ligand bond in AlÀCp complexes. It is instructive to examine the simple AlCp half-metallocene, as all the AlÀCp bonds in larger systems considered here display similar features.…”

Au108S24(PPh3)16: A Highly Symmetric Nanoscale Gold Cluster Confirms the General Concept of Metalloid Clusters

“…[18] Hence, the Au atoms in the 3rd shell of 1 show a completely different arrangement (Figure 2 d) and cap the super-octahedron at every tip with a planar Au 4 S 4 ring. These six Au 4 S 4 rings are each connected by four more Au atoms which results in a (Au 2 S) 24 sphere.…”

“…The most prominent examples (only one for each of the elements mentioned above) are [Al 77 (N(SiMe 3 ) 2 ) 20 ] 2À , [4] [Ga 84 (N(SiMe 3 ) 2 ) 20 ] 4À , [5] Ge 18 [Si-(SiMe 3 ) 3 ] 6 , [6] Sn 15 Ar 6 (Ar = NSiMe 3 Dipp; Dipp = 2,6-iPr 2 -C 6 H 3 ), [7] and Pb 10 [Si(SiMe 3 ) 3 ] 6 . [8] These metalloid clusters are synthesized via different synthetic strategies: [Al 77 6 were obtained via the reduction of a M II precursor.…”

“…In contrast, further calculations by Jiang et al [30] indicate that the staple motif is energetically more favorable, being actually the most favored structural motive in thiol-protected metalloid gold clusters. [18] However, the arrangement of Au and S atoms in the outer shell of 1 indicates that other structural motives also have to be taken into account, because Au 2 S units can act as a protecting ligand shell. [31] The (Au 2 S) 24 sphere only incompletely shields the inner Au 44 core and therefore additional 16 gold atoms are attached to the cluster which are further bound to one PPh 3 ligand each.…”

Coordination chemistry of 3- and 4-mercaptobenzoate ligands: Versatile hydrogen-bonding isomers of the thiosalicylate (2-mercaptobenzoate) ligand

“…[96] The relationship between Au102(4MBA)44 and large metalloid clusters of gallium and aluminium has also been explored. [97] The ESI mass spectrum of Au102(4MBA)44 showed a series of ions having m/z ratios that correspond to a series of ions in different protonation states, while MALDI TOF mass spectrometry showed a broad peak at around 22,000 Da consistent with a species containing 102 Au and 44 S atoms. [92] The UV-visible spectrum of Au102(4MBA)44 shows a peak at 269 nm due to the 4MBA ligand, but no surface plasmon resonance band, consistent with other gold clusters < 2 nm in size.…”