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

Abstract

Complex IrH 5 (P i Pr 3 ) 2 (1) activates two different σbonds of 3-phenoxy-1-phenylisoquinoline, 2-(1H-benzimidazol-2yl)-6-phenylpyridine, 2- 6), and IrH{κ 3 -N,C,C-[py-C 6 HMe 2 -C 5 H 3 N]}(P i Pr 3 ) 2 (7), respectively. The activations are sequential, with the second generally being the slowest. Accordingly, dihydride intermediates IrH 2 {κ 2 -C,N-[C 6 H 4 -isoqui-O-C 6 H 5 ]}(P i Pr 3 ) 2 (2d), IrH 2 {κ 2 -N,N-[NBzim-py-C 6 H 5 ]}(P i Pr 3 ) 2 (3d), IrH 2 {κ 2 -N,N-[Ind-py-C 6 H 5 ]}(P i Pr 3 ) 2 (4d), and IrH 2 {κ 2 -N,C-[py-C 6 HMe 2 -py]}(P i Pr 3 ) 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(sp 3 )−H arylation of N,Ndimethylaniline 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.