Highly Stable Carboranyl Ligated Gold Nano-Catalysts for Regioselective Aromatic Bromination

Abstract

Achieving electronic/steric control and realizing selectivity regulation in nanocatalysis remains a formidable challenge, as the dynamic nature of metal-ligand interfaces, including dissolution (metal leaching) and structural reconstruction, poses significant obstacles. Herein, we disclose carboranyls (CBs) as unprecedented carbon-bonded functional ligands (Eads.CB-Au(111)=−2.90 eV) for gold nanoparticles (AuNPs), showcasing their exceptional stabilization capability that is attributed by strong Au−C bonds combined with B−H⋅⋅⋅Au interactions. The synthesized CB@AuNPs exhibit core(Aun)-satellite(CB2Au−) structure, showing high stability towards multiple stimuli (110 °C, pH=1–12, thiol etchants). In addition, different from conventional AuNP catalysts such as triphenylphosphine (PPh3) stabilized AuNPs, dissolution of catalytically active gold species was suppressed in CB@AuNPs under the reaction conditions. Leveraging these distinct features, CB@AuNPs realized outstanding p : o selectivities in aromatic bromination. Unbiased arenes including chlorobenzene (up to >30 : 1), bromobenzene (15 : 1) and phenyl acrylate were examined using CB@AuNPs as catalysts to afford highly-selective p-products. Both carboranyl ligands and carboranyl derived counterions are crucial for such regioselective transformation. This work has provided valuable insights for AuNPs in realizing diverse regioselective transformations.