RhI Ar/AuI Ar' Transmetalation: A Case of Group Exchange Pivoting on the Formation of M-M' Bonds through Oxidative Insertion.

By combining kinetic experiments, theoretical calculations, and microkinetic modeling, we show that Pf/Rf (C6 F5 /C6 Cl2 F3 ) exchange between [AuPf(AsPh3 )] and trans-[RhRf(CO)(AsPh3 )2 ] does not occur by typical concerted Pf/Rf transmetalation via electron-deficient double bridges. Instead, it involves asymmetric oxidative insertion of the RhI complex into the (Ph3 As)Au-Pf bond to produce a [(Ph3 As)Au-RhPfRf(CO)(AsPh3 )2 ] intermediate, followed by isomerization and reductive elimination of [AuRf(AsPh3 )]. Interesting differences were found between the LAu-Ar asymmetric oxidative insertion and the classical oxidative addition process of H2 to Vaska complexes.