Structural evolution of small ruthenium cluster anions.

Area of Science:

• Materials Science
• Computational Chemistry
• Physical Chemistry

Background:

• Understanding the structural properties of metal clusters is crucial for catalysis and materials design.
• Ruthenium clusters are of interest due to their catalytic activity and unique electronic properties.

Purpose of the Study:

• To determine the structural motifs of ruthenium cluster anions (Ru$_{n}^{-}$) from n=8 to 20.
• To investigate the size-dependent structural transitions in these clusters.
• To complement experimental findings with theoretical predictions for smaller clusters.

Main Methods:

• Trapped ion electron diffraction (TIED) was employed for experimental structural determination.
• Density functional theory (DFT) computations were utilized for theoretical analysis and prediction.
• A combination of experimental and computational methods provided a comprehensive structural investigation.

Main Results:

• Three distinct structural motifs were identified for Ru$_{n}^{-}$ (n=8-20): simple cubic (Ru$_{8-12}^{-}$), double-layered hexagonal (Ru$_{13-16}^{-}$), and close-packed structures (Ru$_{17-20}^{-}$).
• Hexagonal close-packed (HCP) stacking was observed for Ru$_{17}^{-}$ and octahedral structures for Ru$_{18-20}^{-}$.
• DFT calculations predicted simple cubic structures for smaller, experimentally inaccessible clusters (Ru$_{4-7}^{-}$).

Conclusions:

• Ruthenium cluster anions display a clear size-dependent structural evolution.
• The study reveals a transition from simple cubic to hexagonal and close-packed structures as cluster size increases.
• The combined experimental and computational approach provides valuable insights into the fundamental structures of ruthenium clusters.