RhIAr/AuIAr′ Transmetalation: A Case of Group Exchange Pivoting on the Formation of M−M′ Bonds through Oxidative Insertion

Transmetalation, but not as you know it: A combination of kinetic studies, theoretical calculations, and microkinetic modeling showed that C₆F₅ (Pf)/C₆Cl₂F₃ (Rf) 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, nucleophilic attack of Rh^I at the gold center triggers asymmetric oxidative insertion of Rh into the Au−aryl bond (see scheme).

Abstract

By combining kinetic experiments, theoretical calculations, and microkinetic modeling, we show that Pf/Rf (C₆F₅/C₆Cl₂F₃) 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 Rh^I complex into the (Ph₃As)Au−Pf bond to produce a [(Ph₃As)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.

from A via a.sfakia on Inoreader http://bit.ly/2CMAfxM