Rh Ar/Au 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 (C F /C Cl F ) exchange between [AuPf(AsPh )] and trans-[RhRf(CO)(AsPh ) ] does not occur by typical concerted Pf/Rf transmetalation via electron-deficient double bridges. Instead, it involves asymmetric oxidative insertion of the Rh complex into the (Ph As)Au-Pf bond to produce a [(Ph As)Au-RhPfRf(CO)(AsPh ) ] intermediate, followed by isomerization and reductive elimination of [AuRf(AsPh )]. Interesting differences were found between the LAu-Ar asymmetric oxidative insertion and the classical oxidative addition process of H to Vaska complexes.