Structural Transformation of Metastable Two-Electron Superatom Au-Doped Cu-Rich Alloy Nanocluster

The ability to fabricate bimetallic clusters with atomic precision offers promising prospects for elucidating the correlations between their structures and properties. Nevertheless, achieving precise control at the atomic level in the production of clusters, including the quantity of dopant, characteristic of ligands, charge state of precursors, and structural transformation, have remained a challenge. Herein, we report the synthesis, purification, and characterization of a new bimetallic hydride cluster, [AuCu₁₁(H){S₂P(OPr)₂}₆(C≡CPh)₃] (AuCu). The hydride position in AuCu was determined using DFT calculations. AuCu comprises a ligand-stabilized defective fcc Au@Cu₁₁ cuboctahedron. AuCu is metastable and undergoes a spontaneous transformation through ligand exchange into the isostructural [AuCu₁₁(Cl){S₂P(OPr)₂}₆(C≡CPh)₃] (AuCu) and into the complete cuboctahedral [AuCu₁₂{S₂P(OPr)₂}₆(C≡CPh)₄]⁺ (AuCu) through an increase in nuclearity. These structural transformations were tracked by NMR and mass spectrometry.