Hydride-Containing Eight-Electron Pt/Ag Superatoms: Structure, Bonding, and Multi-NMR Studies

Area of Science:

• Inorganic Chemistry
• Materials Science
• Nanotechnology
• Superatomic Chemistry

Background:

• Hydride-doped noble metal nanoclusters are of interest, with hydride suggested to be part of the superatom core.
• Experimental evidence for the precise location of encapsulated hydride in these nanoclusters has been lacking.
• Understanding the structure-property relationships of superatomic nanoclusters is crucial for their application.

Purpose of the Study:

• To experimentally determine the exact location of hydride within a platinum/silver alloy nanocluster.
• To characterize the solid-state and solution structures of hydride-doped platinum/silver nanoclusters.
• To investigate the electronic structure and bonding of the superatomic core using computational methods.

Main Methods:

• Synthesis of hydride-doped platinum/silver alloy nanoclusters: [PtHAg₁₉(dtp/desp)₁₂].
• Single-crystal X-ray diffraction to determine solid-state structures.
• Neutron diffraction to precisely locate the four-coordinated hydride.
• Nuclear Magnetic Resonance (NMR) spectroscopy (¹H, ¹⁹⁵Pt, multi-NMR) to study solution structures and isomers.
• Density Functional Theory (DFT) calculations to analyze electronic structure and isomer energies.

Main Results:

• The precise location of a four-coordinated hydride was determined by neutron diffraction for the first time, situated within a central PtH unit.
• X-ray structures revealed a [PtH@Ag₁₂] core encapsulated by silver atoms and dichalcogenolates, exhibiting different symmetries (C₁ and C₃) in solid state.
• NMR studies indicated the coexistence of C₁ and C₃ isomers in solution, supported by DFT calculations showing similar energies.
• DFT calculations confirmed the [PtH@Ag₁₂]⁵⁺ kernel as a closed-shell eight-electron superatomic core, with hydride contributing significantly to its electron count.

Conclusions:

• This study provides the first experimental proof of the hydride's location within the superatom core of a noble metal nanocluster.
• The results highlight the structural diversity and isomeric complexity of hydride-doped platinum/silver nanoclusters in both solid and solution states.
• The findings advance the understanding of superatom chemistry and the role of encapsulated hydride in stabilizing these unique nanostructures.