Evidence of superatom electronic shells in ligand-stabilized aluminum clusters

Ligand-stabilized aluminum clusters are investigated by density functional theory calculations. Analysis of Kohn-Sham molecular orbitals and projected density of states uncovers an electronic shell structure that adheres to the superatom complex model for ligand-stabilized aluminum clusters. In this current study, we explain how the superatom complex electron-counting rule is influenced by the electron-withdrawing ligand and a dopant atom in the metallic core. The results may guide the prediction of new stable ligand-stabilized (superatom) complexes, regardless of core and electron-withdrawing ligand composition.

A 58-electron superatom-complex model for the magic phosphine-protected gold clusters (Schmid-gold, Nanogold®) of 1.4-nm dimension

We have re-investigated the structural identity of the famous gold-phosphine-halide Au:PR3:X compound having 55–69 gold atoms and core size of 1.4 nm (similar to “Schmid gold” or Nanogold®) from the viewpoint of the Superatom-Complex (SAC) model for ligand protected metal clusters, and in consideration of the ligand-adatom groups observed previously for the structurally known 39-atom cluster [Au39(PR3)14Cl6]−1. Density functional theory is used to define the formation energy of various compositions and structures, enabling a comparison of the stability of different cluster-sizes. In agreement with the SAC model, we find a strong correlation between optimal energy and delocalized electron sh…

A unified view of ligand-protected gold clusters as superatom complexes

Synthesis, characterization, and functionalization of self-assembled, ligand-stabilized gold nanoparticles are long-standing issues in the chemistry of nanomaterials. Factors driving the thermodynamic stability of well documented discrete sizes are largely unknown. Herein, we provide a unified view of principles that underlie the stability of particles protected by thiolate (SR) or phosphine and halide (PR 3 , X) ligands. The picture has emerged from analysis of large-scale density functional theory calculations of structurally characterized compounds, namely Au 102 (SR) 44 , Au 39 (PR 3 ) 14 X 6 − , Au 11 (PR 3 ) 7 X 3 , and Au 13 (PR 3 ) 10 X 2 3+ , where X is either a halogen or a thiol…

On the Structure of Thiolate-Protected Au25

Density functional theory is used to explore the structure of Au25(RS)18. The preferred structure consists of an icosahedral Au13 core protected by 6 RS-Au-RS-Au-RS units. The enhanced stability of the structure as an anion is found to originate from closure of an eight-electron shell for delocalized Au(6s) electrons. The evaluated XRD pattern and optical spectra are in good agreement with experimental data.

The Al 50 Cp* 12 Cluster – A 138‐Electron Closed Shell ( L = 6) Superatom

Metal clusters stabilized by a surface ligand shell represent an interesting intermediate state of matter between molecular metal-ligand complexes and bulk metal. Such "metalloid" clusters are characterized by the balance between metal-metal bonds in the core and metal-ligand bonds at the exterior of the cluster. In previous studies, the electronic stability for the Al50Cp*(12) cluster was not fully understood. We show here that the known cluster Al50Cp*(12) can be considered as an analogue to a giant atom ("superatom") with 138 sp electrons organized in concentric angular momentum shells up to L = 6 symmetry.

Protected Metallic Clusters, Quantum Wells and Metal-Nanocrystal Molecules