Crystal Structure of the PdAu24(SR)18(0) Superatom

Area of Science:

• Inorganic Chemistry
• Materials Science
• Nanotechnology

Background:

• Gold clusters (Au25(SR)18) are nanoscale materials with unique electronic and optical properties.
• Doping these clusters with other metals, like palladium (Pd), can further tune their characteristics.
• Understanding the precise atomic arrangement in doped clusters is crucial for predicting their behavior.

Purpose of the Study:

• To determine the single-crystal X-ray structure of palladium-doped gold clusters, specifically PdAu24(SR)18.
• To elucidate the site-specific localization of the palladium atom within the gold cluster.
• To investigate the electronic structure and stability of the doped cluster in relation to undoped counterparts.

Main Methods:

• Single-crystal X-ray diffraction was employed to solve the crystal structure of Pd-doped Au25(SR)18.
• Electrochemical methods were used for comparison of charge states.
• Analysis of bond lengths and electronic properties (Jahn-Teller effect) was performed.

Main Results:

• The single-crystal X-ray structure confirmed that the palladium atom is exclusively located at the centroid of the Au25(SR)18 cluster.
• The PdAu24(SR)18(0) cluster is isoelectronic with Au25(SR)18(+1), exhibiting a similar magnitude of the first-order Jahn-Teller effect.
• Shorter Pd-Au bonds compared to Au-Au bonds in the undoped cluster explain the enhanced stability of PdAu24(SR)18.

Conclusions:

• The precise localization of palladium at the cluster centroid is confirmed by X-ray crystallography.
• The PdAu24(SR)18(0) cluster aligns with superatom theory and exhibits electronic properties comparable to Au25(SR)18(+1).
• Enhanced cluster stability is attributed to favorable Pd-Au bonding, offering insights for designing novel doped nanoclusters.