-Alkylation and -Methylation of Amines with Alcohols Catalyzed by Nitrile-Substituted NHC-Ir(III) and NHC-Ru(II) Complexes.

A series of nitrile-modified -heterocyclic carbene (NHC) complexes of Ir(III) (-) and Ru(II) (-) have been prepared by transmetallation of [IrCp*Cl] and [RuCl(-cymene)] forming an NHC-Ag complex. The structures of all complexes were characterized by H NMR, C NMR, and Fourier transform infrared (FT-IR) spectroscopies. And the structures were clearly elucidated by performing X-ray diffraction studies on , , and single crystals. The complexes of NHC-Ir(III) (-) and NHC-Ru(II) (-) were investigated in the -alkylation reaction of aniline derivatives with benzyl alcohols to form -benzyl amines and in the -methylation reaction of aniline derivatives with methanol. Both reactions were performed in solvent-free media. The Ir(III) complexes (-) were found to perform essentially better than similar Ru(II) complexes (-) in the -alkylation and -methylation reactions. Among the Ir(III) complexes (-), the best results were obtained with . The catalytic mechanisms of both reactions were revealed by H NMR study. Formation of Ir-hydride species was observed for both reactions. This new report provides useful information to evaluate the activity of complexes and the differences in sensitivity between the NHCs.