Polymorphism in Atomically Precise Cu₂₃ Nanocluster Incorporating Tetrahedral [Cu₄]⁰ Kernel

Area of Science:

• Materials Science
• Nanotechnology
• Inorganic Chemistry

Background:

• Copper nanoclusters typically exhibit instability, hindering precise structural determination.
• Atom-precise characterization of nanoclusters is crucial for understanding their properties and applications.

Purpose of the Study:

• To synthesize and structurally elucidate a stable copper nanocluster.
• To develop a controllable method for producing polymorphic copper nanoclusters.

Main Methods:

• Utilized a gradient reduction strategy (GRS) involving Cu(II), Cu(I), and Cu(0) intermediates.
• Employed specific precursors: Cu(CF3COO)2, t-BuC≡CH, Cu powder, and Ph2SiH2.
• Analyzed nanocluster structure using solid-state characterization techniques.

Main Results:

• Successfully synthesized an air- and moisture-stable 23-copper nanocluster (SD/Cu23a or SD/Cu23b).
• Determined the structure: a [Cu4]0 tetrahedral core within a Cu19 shell, stabilized by t-BuC≡C- and CF3COO- ligands.
• Identified the Cu23 nanocluster as a rare four-electron superatom with 1S21P2 electronic configuration.
• Observed two distinct polymorphs (R3c and R3̅) dependent on crystallization solvent, influenced by intermolecular interactions.

Conclusions:

• The gradient reduction strategy is effective for synthesizing stable, atom-precise copper nanoclusters.
• Demonstrated precise control over the polymorphic formation of copper nanoclusters.
• Advanced the fundamental understanding of copper nanocluster synthesis and structural diversity.