Yan Jiang#, Le-Jie Liu#, Jia-Jia Ma, Xiao-Ya Dou, Ling-Ya Peng*, Ganglong Cui*, and Yu Fang. JACS Au. 2026, DOI: 10.1021/jacsau.5c01536

Metal complex-catalyzed cross-coupling reactions have achieved remarkable progress in organic synthesis. The introduction of Au complexes has further revitalized this field, leveraging their strong π-acidity to efficiently activate unsaturated C–C bonds. However, the use of external oxidants and photosensitizers becomes a prerequisite for the cross-coupling reaction. The direct photocatalytic cross-coupling reaction of diazonium salts using a standalone Au(I) complex is still in its infancy. In 2024, Peris et al. reported an Au complex [(NDI-NHC)–Au–Cl], which catalyzes the cross-coupling reaction of aryldiazonium salts and alkynyl-silanes. However, the mechanistic understanding of single-component Au photocatalytic cross-coupling reactions remains underdeveloped, which would be crucial for the design of catalytic systems.

Figure 1. Calculated radiative and nonradiative processes of [(NDI-NHC)−Au−Cl], the adiabatic energies at the MS-CASPT2 level of the excited states, the largest Huang−Rhys factors, and their associated vibrational modes are presented.

Upon photoexcitation, a four-state model (S₀, S₁, T₂, and T₁) of the photophysical process is identified. The reaction proceeds via a triplet-state-initiated tandem comprising single electron transfer (SET), N₂ extrusion, radical addition, and intersystem crossing, culminating in reductive elimination to complete the catalytic cycle. Furthermore, introducing electron-withdrawing groups such as the cyano group into the aryldiazonium scaffold enhances SET efficiency by a certain cancellation of the reorganization energy by driving energy, thereby reducing the free energy barrier. The nonradiative decay dominates the reaction coordinates. Leveraging these mechanistic insights, the SET modulation strategy is theoretically extended to Ag and Cu complexes, which exhibit comparably high performance in C–C coupling reactions along with improved cost-effectiveness. This work not only establishes fundamental structure-reactivity relationships in Au-photocatalyzed cross-couplings but also provides a general framework for optimizing photoinduced electron transfer processes.

This work systematically elucidates the underlying mechanism of the reaction between aryldiazonium salts and alkynylsilanes catalyzed by N-heterocyclic carbene Au(I) complexes. By effectively modulating the single-electron transfer process based on Marcus theory, the established model was further extended to other d¹⁰ metal complex systems, providing an important theoretical foundation for subsequent research on C–C coupling reactions and the rational design of catalysts.

First Authors: Jiang Yan and Liu Lejie, master’s student, Shaanxi Normal University

Correspondence Authors: Dr. Peng Lingya, Shaanxi Normal University; Prof. Cui Ganglong, Beijing Normal University

Full Text Link: https://pubs.acs.org/doi/10.1021/jacsau.5c01536?ref=PDF