Peer-reviewedCC BY-NC-ND 4.0ACS Omega12 Oct 2026

Water-Soluble Au–NHC Complexes for Aqueous A3 Coupling: Ligand Architecture, Catalyst Speciation, and Reuse

Liddier O. Pérez¹
Diana E. Vita²
Gustavo F. Silbestri²
Sebastián A. Testero¹

¹Instituto de Química Rosario-IQUIR (CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario , Suipacha 531 , ,
²Universidad Nacional Del Sur (UNS)-CONICET , , Avenue Alem 1253 , ,

Abstract

The development of water-soluble gold catalysts for reactions in water remains challenging because catalyst speciation and oxidation-state changes can strongly influence activity and stability. Herein, two water-soluble Au(III)–NHC complexes (2a–b)–selected for their distinct structural features–were synthesized and evaluated in the A3-coupling reaction in aqueous media, together with their corresponding Au(I) precursor. Among the Au(III)–NHC precatalysts 2a and 2b, complex 2b displayed superior activity compared to 2a, affording quantitative yields at 1 mol % and maintaining significant conversion even at 0.2 mol % loading. Steric analysis based on %VBur calculations showed that, upon Au–Cl bond cleavage, the sulfonate side chain in 2b cyclized and coordinates to the metal center, leading to a significant increase in buried volume. Recycling experiments showed progressive deactivation of both Au(III) precatalysts, while NMR monitoring in the presence of phenylacetylene provided evidence for changes in Au(III)/Au(I) speciation, including formation of Au(I) species. Addition of catalytic amounts of CuCl2 improved the recycling of 2b, although catalyst reuse remained limited to three cycles. These results establish a correlation between ligand-controlled steric modulation, oxidation-state stability, and catalytic performance in aqueous Au(III)–NHC systems for the multicomponent A3-coupling reaction.

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BibTeX RIS

BibTeX

@article{perez2026watersoluble,
  title = {{Water-Soluble Au–NHC Complexes for Aqueous A3 Coupling: Ligand Architecture, Catalyst Speciation, and Reuse}},
  author = {Liddier O. Pérez and Diana E. Vita and Gustavo F. Silbestri and Sebastián A. Testero},
  journal = {ACS Omega},
  year = {2026},
  month = oct,
  doi = {10.1021/acsomega.6c11361},
  url = {https://pubs.acs.org/acsodf/article/11/42/65917/5449259/Water-Soluble-Au-NHC-Complexes-for-Aqueous-A3},
  note = {CC BY-NC-ND 4.0},
}

RIS

TY  - JOUR
TI  - Water-Soluble Au–NHC Complexes for Aqueous A3 Coupling: Ligand Architecture, Catalyst Speciation, and Reuse
AU  - Liddier O. Pérez
AU  - Diana E. Vita
AU  - Gustavo F. Silbestri
AU  - Sebastián A. Testero
PY  - 2026
DA  - 2026/10/12
JO  - ACS Omega
DO  - 10.1021/acsomega.6c11361
UR  - https://pubs.acs.org/acsodf/article/11/42/65917/5449259/Water-Soluble-Au-NHC-Complexes-for-Aqueous-A3
AB  - The development of water-soluble gold catalysts for reactions in water remains challenging because catalyst speciation and oxidation-state changes can strongly influence activity and stability. Herein, two water-soluble Au(III)–NHC complexes (2a–b)–selected for their distinct structural features–were synthesized and evaluated in the A3-coupling reaction in aqueous media, together with their corresponding Au(I) precursor. Among the Au(III)–NHC precatalysts 2a and 2b, complex 2b displayed superior activity compared to 2a, affording quantitative yields at 1 mol % and maintaining significant conversion even at 0.2 mol % loading. Steric analysis based on %VBur calculations showed that, upon Au–Cl bond cleavage, the sulfonate side chain in 2b cyclized and coordinates to the metal center, leading to a significant increase in buried volume. Recycling experiments showed progressive deactivation of both Au(III) precatalysts, while NMR monitoring in the presence of phenylacetylene provided evidence for changes in Au(III)/Au(I) speciation, including formation of Au(I) species. Addition of catalytic amounts of CuCl2 improved the recycling of 2b, although catalyst reuse remained limited to three cycles. These results establish a correlation between ligand-controlled steric modulation, oxidation-state stability, and catalytic performance in aqueous Au(III)–NHC systems for the multicomponent A3-coupling reaction.
SN  - 2470-1343
ER  -

Abstract

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