Pseudo-tris(heteroleptic) red phosphorescent Iridium(III) complexes bearing a dianionic C,N,C′,N′-tetradentate ligand

1-Phenyl-3-(1-phenyl-1-(pyridin-2-yl)ethyl)isoquinoline (H2MeL) has been prepared by Pd(N-XantPhos)-catalyzed “deprotonative cross-coupling processes” to synthesize new phosphorescent red iridium(III) emitters (601–732 nm), including the carbonyl derivative Ir(κ4-cis-C,C′-cis-N,N′-MeL)Cl(CO) and the acetylacetonate compound Ir(κ4-cis-C,C′-cis-N,N′-MeL)(acac). The tetradentate 6e-donor ligand (6tt′) of these complexes is formed by two different bidentate units, namely, an orthometalated 2-phenylisoquinoline and an orthometalated 2-benzylpyridine. The link between the bidentate units reduces the number of possible stereoisomers of the structures [6tt′ + 3b] (3b = bidentate 3e-donor ligand), with respect to a [3b + 3b′ + 3b″] emitter containing three free bidentate units, and it permits a noticeable stereocontrol. Thus, the isomers fac-Ir(κ4-cis-C,C′-cis-N,N′-MeL){κ2-C,N-(C6H4-py)}, mer-Ir(κ4-cis-C,C′-cis-N,N′-MeL){κ2-C,N-(C6H3R-py)}, and mer-Ir(κ4-trans-C,C′-cis-N,N′-MeL){κ2-C,N-(C6HR-py)} (R = H, Me) have also been selectively obtained. The new emitters display short lifetimes (0.7–4.6 μs) and quantum yields in a doped poly(methyl methacrylate) film at 5 wt % and 2-methyltetrahydrofuran at room temperature between 0.08 and 0.58. The acetylacetonate complex Ir(κ4-cis-C,C′-cis-N,N′-MeL)(acac) has been used as a dopant for a red PhOLED device with an electroluminescence λmax of 672 nm and an external quantum efficiency of 3.4% at 10 mA/cm2.Financial support was provided by MINECO of Spain [CTQ2017-82935-P (AEI/FEDER, UE) and RED2018-102387-T], Gobierno de Aragón (E06_20R and LMP148_18), FEDER, and the European Social Fund. The CESGA Supercomputing Center and BIFI Institute are also acknowledged for the use of their computational resources.Peer reviewe