Gold versus palladium catalyzed cross-coupling reactions: a DFT mechanistic study on the chemoselective arylation of alkyl nitriles

A DFT mechanistic study on the arylation of alkyl nitriles has been performed to shed light on the different chemoselectivity observed for gold and palladium complexes. Starting from the same substrates, recent experimental studies showed peculiar C-N coupling promoted by MeDalphosAuCl, whereas it is well known that P^P Pd complexes give C-C coupling. The routes for C-N and C-C coupling were investigated in detail for both catalytic systems, highlighting similarities and differences between the two metals with isoelectronic valence shell redox couples (Pd(0)/Pd(II) and Au(I)/Au(III)). The computational study disclosed the key role of water, in determining the chemoselectivity of the reaction promoted by the gold system, associated with the active participation of AgSbF₆, directly involved in relevant intermediates and transition states.