All-N-Heterocyclic-Carbene Protected Superatomic Ag₈ Cluster

Area of Science:

• Materials Science
• Nanotechnology
• Inorganic Chemistry

Background:

• Atomically precise coinage metal nanoclusters (CMNCs) are gaining attention for their unique structures and properties.
• The synthesis of all-N-heterocyclic-carbene (NHC)-protected atomically precise silver nanoclusters remains an underexplored area.

Purpose of the Study:

• To report the synthesis and structural characterization of the first all-NHC-protected superatomic silver cluster.
• To investigate the bonding nature and stabilization mechanisms within the synthesized cluster.

Main Methods:

• One-pot synthesis involving Ag2O and a bisimidazolium salt under alkaline conditions.
• Characterization using single-crystal X-ray diffraction, multinuclear nuclear magnetic resonance (NMR) spectroscopy, and high-resolution electrospray-ionization (HR-ESI) mass spectrometry.
• Computational analysis using energy decomposition analysis (EDA) combined with natural orbital for chemical valence (NOCV).

Main Results:

• Successful synthesis and crystal structure determination of a novel NHC-stabilized Ag8 cluster (Ag8K2L4(CO3)2(PF6)6).
• Identification of a stable Ag8 ring at the cluster's core.
• Computational analysis revealed that stabilization arises from strong electrostatic attraction between the Ag8 ring and the NHC ligands.

Conclusions:

• This study presents the first all-NHC-protected superatomic silver cluster, expanding the scope of NHC-protected metal clusters.
• The findings highlight the significant role of electrostatic interactions in stabilizing these nanoclusters.
• This work is anticipated to foster new applications for NHC ligands in designing functional metal nanoclusters.