Bidentate Acyclic Diamino Carbene-Stabilized Gold Nanoparticles from Symmetric and Asymmetric Gold(I) Complexes: Synthesis, Characterization, and Catalytic Activity.

A series of gold nanoparticles (AuNPs) stabilized by bidentate acyclic diamino carbenes (ADCs) were synthesized via the reduction of dimeric gold(I) complexes. The resulting ADC-AuNPs were characterized by NMR spectroscopy, UV-vis spectroscopy, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA), revealing nanoparticles with a narrow size distribution and sizes ranging from 1.7 to 3.3 nm. This synthetic approach was extended to an asymmetric dinuclear ADC-gold(I) complex, affording slightly larger AuNPs (∼4 nm) upon reduction. The ADC-AuNPs with shorter linkers exhibited significant catalytic activity for the reduction of 4-nitrophenol, demonstrating a versatile and efficient route to catalytically active gold nanoparticles stabilized by both symmetric and asymmetric ADC ligands.