Cationic gold clusters with eight valence electrons: possible spherical aromatic systems with Sigma holes

Abstract

The lowest energy structures of Au9+ and Au113+ are aromatic with relatively spherical polyhedra, like Au102+. However, the lowest energy Au124+ structure has a central planar unit with four Au4 tetrahedra. The surfaces of these clusters have σ-holes.

Photoluminescence control by atomically precise surface metallization of C-centered hexagold(i) clusters using N-heterocyclic carbenes

“…Au 4 , Au 10 , Au 20 ) have long been explored because they can be regarded as fragments of bulk gold and have been found or predicted to exhibit unique structural properties such as wide energy gap and spherical aromaticity. [48][49][50][51][52][53][54][61][62][63] Despite the fact that Au 4 has actually been reported, structure information on the latter two clusters is not yet available. As shown in the simplied CAu I 6 Ag I 4 structure in Fig.…”

“…By introducing an additional ligand in the wingtip group of the carbene ligand and increasing the number of Ag I ions bound to CAu I 6 , strong red phosphorescence with a QY of 0.40 and a lifetime of 1.41 μs was observed in CH 2 Cl 2 , both of which were significantly improved compared to cluster 3. The CAu I 6 Ag I 4 tetrahedron has edges of 5.544–5.947 Å, which is comparable to the Au 10 nanocluster, 48,49 one of the long pursued tetrahedral gold nanoclusters. This result indicates that not only the coverage of the cluster surface by additional metal ions but also the rigidity of the coordination structure is important for the strong and long-lived phosphorescent properties of metal clusters.…”

“…The structure will also provide a useful new idea for rational synthesis of tetrahedral Au 10 and Au 20 . [48][49][50][51][52][53][54]…”