Electrosynthesis of Atomically Precise Au Nanoclusters

Innovation in synthesis methodologies is crucial for advancing the discovery of new materials. This work reports the electrosynthesis of a [Au₁₃(4-^tBuPhC≡C)₂(Dppe)₅]Cl₃ nanocluster (Au₁₃ NC) protected by alkynyl and phosphine ligands. From simple precursor, HAuCl₄ and ligands, the whole synthesis is driven by a constant potential in single electrolytic cell. X-ray crystallography determines its total structure. Control experiments, cyclic voltammetry, Proton Nuclear Magnetic Resonance (¹H NMR), gas chromatography, and other characterizations demonstrate that a critical tetranuclear Au(I) complex defines the electrochemical redox behavior of the reaction solution. The critical role of a base (e.g., triethylamine) is to suppress the hydrogen evolution reaction at the cathode, paving the way for the reduction of Au ions. To resolve the problem of over-reduction and deposition of Au on the cathode, pulsed electrolysis, which is specific to electrosynthesis is employed. It significantly improves the reaction rate and the isolated yield of Au₁₃. To extend the application scope, another four NCs protected by different ligands, [Au₁₃(4-FPhC≡C)₂(Dppe)₅]Cl₃, [Au₈(2-CF₃PhC≡C)₂(Dppp)₄](PF₆)₂, [Au₁₁(Dppp)₅]Cl₃, and [Au₈(SC₂H₄Ph)₂(Dppp)₄]Cl₂ are synthesized electrochemically, demonstrating the versatility of the strategy.