Small platinum cluster hydrides in the gas phase

Area of Science:

• Inorganic Chemistry
• Physical Chemistry
• Materials Science

Background:

• Cationic platinum clusters are model systems for catalysis.
• Understanding hydrogen binding on metal clusters is crucial for catalysis and materials science.
• Previous theoretical studies predicted specific hydrogen binding sites on platinum clusters.

Purpose of the Study:

• To investigate the reactions of small cationic platinum clusters (Pt2(+)-Pt7(+)) with molecular hydrogen.
• To determine the structures of the resulting hydride complexes.
• To compare experimental findings with theoretical predictions.

Main Methods:

• Infrared (IR) spectroscopy was used to analyze hydride complex structures.
• Infrared multiple-photon dissociation (IR-MPD) spectroscopy (550-2050 cm(-1)) was employed for structural analysis of saturated complexes.
• Density functional theory (DFT)-based calculations complemented experimental spectroscopic data.

Main Results:

• Relative reaction rates for the first H2 addition to platinum clusters were determined.
• High hydrogen saturation coverages were observed, yielding high H atom per Pt atom ratios.
• Experimental results revealed molecularly bound hydrogen, bridge-bound, and atop-bound hydrogen atoms in low-energy structures, contradicting prior theoretical predictions.

Conclusions:

• Cationic platinum clusters exhibit complex hydrogen binding behavior.
• Experimental structural analysis provides new insights into hydrogen-metal cluster interactions.
• The findings challenge existing theoretical models and necessitate revised understanding of hydrogen storage and catalysis on platinum clusters.