Tetraorganylargentate(III) Complexes: Key Intermediates in Silver-Mediated Cross-Coupling Reactions

The use of silver as a catalyst in cross-coupling reactions remains underdeveloped. We show by means of electrospray-ionization mass spectrometry that the diorganylargentates LiAgR′2·Li­(CN) (R′ = Me, Bu) formed in situ react with a wide scope of alkyl and aryl halides RX to afford the tetraorganylargentate­(III) complexes R′3AgR–. Upon fragmentation in the gas phase, these high-valent species readily undergo reductive elimination. The trimethylorganylargentates Me3AgR– furnish the synthetically desired cross-coupling products MeR with high selectivity, whereas the tributylorganylargentates Bu3AgR– yield more of the homocoupling product Bu2. Quantum chemical calculations reproduce the experimentally observed trends in reactivity and moreover provide insight into the structures and energetics of the species involved. Our findings indicate that the facile formation of tetraorganylargentate complexes and their high tendency toward reductive elimination can be exploited for the development of silver-mediated cross-coupling reactions as a viable alternative to established synthetic methods.