Cross-Dehydrogenative Coupling of Secondary Amines with Silanes Catalyzed by Agostic Iridium-NSi Species.

An active catalytic system for the cross-dehydrogenative coupling (CDC) of a wide range of secondary amines with silanes is reported. The iridium(III) derivatives [Ir(H)(X)(κ-NSi)(L)] (NSi = {4,8-dimethylquinoline-2-yloxy}dimethylsilyl; L = coe, X = Cl, ; L = coe, X = OTf, ; L = PCy, X = Cl, ; L = PCy X = OTf, ), which are stabilized by a weak yet noticeable Ir···H-C agostic interaction between the iridium and one of the C-H bonds of the 8-Me substituent of the NSi ligand, have been prepared and fully characterized. These species have proven to be effective catalysts for the CDC of secondary amines with hydrosilanes. The best catalytic performance (TOF = 79,300 h) was obtained using (0.25 mol %), -methylaniline, and HSiMePh. The catalytic activity of the species [Ir(H)(OTf)(κ-NSi)(PCy)] (, NSi = {quinoline-2-yloxy}dimethylsilyl) and [Ir(H)(OTf)(κ-NSi)(PCy)] (, NSi = {4-methylquinoline-2-yloxy}dimethylsilyl), related to but lacking the 8-Me substituent, is markedly lower than that found for . This fact highlights the crucial role of the 8-Me substituent of the NSi ligand in enhancing the catalytic performance of these iridium complexes.