Ag(I)-Induced C–C Reductive Elimination from Pt(II): Role of Ag(I) and Counteranion

Abstract Transition-metal-catalyzed C–C bond formation, including C–H functionalization reactions, often benefits from Lewis acid additives, among which Ag(I) salts are widely used in Pd-catalyzed transformations. Despite this, direct experimental evidence defining the mechanistic role of Lewis acid additives remains limited. Herein, we investigate the role of Ag(I) additives in C–C bond formation using (6-Fp)PtPh2 (1) (6-Fp = 8,8′-(1,2-phenylene)diquinoline) as the starting complex. The reaction of (6-Fp)PtPh2 with different Ag(I) compounds gives significantly different yields for the formation of biphenyl. Unexpectedly, our combined experimental, including 195Pt NMR spectroscopy and X-ray photoelectron spectroscopy, and computational studies reveal that Ag(I) becomes incorporated into the Pt bonding framework to form multimetallic Pt/Ag intermediates that can promote reductive elimination. The Ag(I) counteranion strongly influences the structure and reactivity of these intermediates, giving the rate trend AgTFA ≈ AgOTf > AgNO3 for the formation of biphenyl. These findings provide direct evidence for multimetallic cooperation involving Ag(I) in C–C bond formation.