Base-Promoted Transmetalation Reactions of Protic N-Heterocyclic Carbenes and Acyclic Diamino Carbenes from MnI to AuI: A Mechanistic Study

DFT theoretical calculations for the base-induced transmetalation process of protic N-heterocyclic carbenes of imidazol-2-ylidene type from Mn(I) to Au(I) have been carried out. The reaction mechanism found involves the formation of key reaction intermediates bearing a pure bridging imidazolyl ligand between manganese and gold, as well as transition states showing eta(2) coordination of this ligand, first to gold and then to manganese, before the transmetalation process is completed. In addition, similar DFT calculations have been performed on protic acyclic diamino carbene complexes, showing analogous transferring of the carbene moiety from Mn(I) to Au(I) to afford remarkable mangana-N-heterocyclic carbenes of gold.