C–H, N–H, and O–H Bond Activations to Prepare Phosphorescent Hydride-Iridium(III)-Phosphine Emitters with Photocatalytic Achievement in C–C Coupling Reactions

Complex IrH5 (PiPr3) 2 (1) activates two different σ-bonds of 3-phenoxy-1-phenylisoquinoline, 2- (1H-benzimidazol-2-yl) -6-phenylpyridine, 2- (1H-indol-2-yl) -6-phenylpyridine, 2- (2-hydroxyphenyl) -6-phenylpyridine, N- (2-hydroxyphenyl) -N′-phenylimidazolylidene, and 1, 3-di (2-pyridyl) -4, 6-dimethylbenzene to give IrHκ3-C, N, C-C6H4-isoqui-O-C6H4 (PiPr3) 2 (2), IrHκ3-N, N, C-NBzim-py-C6H4 (PiPr3) 2 (3), IrHκ3-N, N, C-Ind-py-C6H4 (PiPr3) 2 (4), IrHκ3-C, N, O-C6H4-py-C6H4O (PiPr3) 2 (5), IrHκ3-C, C, O-C6H4-Im-C6H4O (PiPr3) 2 (6), and IrHκ3-N, C, C-py-C6HMe2-C5H3N (PiPr3) 2 (7), respectively. The activations are sequential, with the second generally being the slowest. Accordingly, dihydride intermediates IrH2κ2-C, N-C6H4-isoqui-O-C6H5 (PiPr3) 2 (2d), IrH2κ2-N, N-NBzim-py-C6H5 (PiPr3) 2 (3d), IrH2κ2-N, N-Ind-py-C6H5 (PiPr3) 2 (4d), and IrH2κ2-N, C-py-C6HMe2-py (PiPr3) 2 (7d) were characterized spectroscopically. Complexes 3 and 5 are green phosphorescent emitters upon photoexcitation, exhibiting good absorption over a wide range of wavelengths, emission quantum yields about 0. 70 in solution, long enough lifetimes (10–17 μs), and reversible electrochemical behavior. In agreement with these features, complex 3 promotes the photocatalytic α-amino C (sp3) –H arylation of N, N-dimethylaniline and N-phenylpiperidine with 1, 4-dicyanobenzene and 4-cyanopyridine under blue LED light irradiation. The C–C coupling products are isolated in high yields with only 2 mol % of photocatalyst after 24 h.