A Unique Au–Ag–Au Triangular Motif in a Trimetallic Halonium Dication: Silver Incorporation in a Gold(I) Catalyst

Abstract

As a result of explorations into the solution chemistry of silver/gold mixtures, a unique diphosphine trimetallic chloronium dication was discovered that incorporates silver-arene chelation and a triangular mixed gold/silver core in the solid state. Notably, it was isolated from a Celite prefiltered solution initially thought to be silver-free. The crystal structure also incorporates the coordination to silver of one fluorine atom of one SbF6(-) counterion. The structure was compared to two new, but well-precedented, phosphine digold chloride cations. DFT calculations supported significant silver-halide and silver-arene interactions in the mixed gold/silver complex and metallophilic interactions in all three complexes. Comparison of computed data revealed that the ωB97X-D functional, which has a long-range corrected hybrid with atom-atom dispersion corrections, gave a better fit to the experimental data compared with the PBE0 functional, which has previously failed to capture aurophilic interactions. Preliminary studies support the presence of the mixed gold/silver structure in solution.

Gold(I)‐Catalysed Asymmetric Hydroamination of Alkenes: A Silver‐ and Solvent‐Dependent Enantiodivergent Reaction

“…We found a good agreement between diffusion coefficient D and hydrodynamic radius rH of all species. This therefore confirmed the presumed nuclearity and coordination of our catalysts, that is to say, two gold atoms coordinated to one diphosphine ligand, and tended to prove any chloride and/or silver‐bridged species, was unlikely. Indeed, compounds with higher molecular volumes and weights would have displayed lower diffusion coefficient D and higher hydrodynamic radius rH.…”

Controlled Interconversion of a Dinuclear Au Species Supported by a Redox‐Active Bridging PNP Ligand Facilitates Ligand‐to‐Gold Electron Transfer

“…Scheme9.Interconversion between species 5 and 7 with AgNTf 2 or HCl and preparation of species 6 from 7 by two-electron oxidation using PhICl 2 ; Au = Au I ; Au = Au III . (12);A u1ÀN2 2.1189(39); P2ÀAu2 2.2362(13);Au2ÀN3 2.1120(41); N2-Au1-P1 174.40 (13); N3-Au2-P2 176.67 (15). ture of these compounds in dichloromethane.…”

Intriguing mechanistic labyrinths in gold(i) catalysis

“…The active species are often generated in situ by chloride abstraction using a silver salt with distinct anions. The innocence of silver in the reaction mixture has been recently questioned, 10 although this aspect merits additional scrutiny. The most convenient catalysts are gold complexes [AuLL′]X or [AuLX] with weakly coordinating neutral (L′) 11 or anionic ligands (X), 12 which could enter catalytic cycles by associative ligand exchange with the substrate.…”