Palladium‐Catalyzed C−H Bond Arylation of Cyclometalated Difluorinated 2‐Arylisoquinolinyl Iridium(III) Complexes

• Published in: Chemistry : a European journal 2021-09, Vol.27 (49), p.12552-12557
• Main Authors: Peng, Marie, Lin, Jinqiang, Lu, Wei, Roisnel, Thierry, Guerchais, Véronique, Doucet, Henri, Soulé, Jean‐François
• Format: Article
• Language: English
• Subjects: Aromatic compounds; Bromides; Catalysis; Chemical Sciences; Chemistry; Crystallography; Electrochemical analysis; Electrochemistry; Fluorine; Functional groups; Hydrogen bonds; Iridium; Iridium compounds; Ligands; luminescence; Palladium; Phosphorescence; post-synthetic modifications; red emitters
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.202102006

The utility of C−H bond functionalization of metalated ligands for the elaboration of aryl‐functionalized difluorinated‐1‐arylisoquinolinyl Ir(III) complexes has been explored. Bis[(3,5‐difluorophenyl)isoquinolinyl](2,2,6,6‐tetramethyl‐3,5‐heptanedionato) iridium(III) undergoes Pd‐catalyzed C−H bond arylation with aryl bromides. The reaction regioselectively occurred at the C−H bond flanked by the two fluorine atoms of the difluoroaryl unit, and on both cyclometalated ligands. This post‐functionalization gives a straightforward access to modified complexes in only one manipulation and allows to introduce thermally sensitive functional groups, such as trifluoromethyl, nitrile, benzoyl, or ester. The X‐ray crystallography, photophysical, and electrochemical properties of the diarylated complexes were investigated. Whatever the nature of the incorporated substituted aryl groups is, all obtained complexes emit red phosphorescence (622–632 nm) with similar lifetimes (1.9–2 μs). Catalysis‐on‐the‐complex was developed to incorporate diversely substituted aryl group on the ligands of neutral cyclometalated Ir(III) complexes. The regioselectivity of Pd‐catalyzed C−H bond arylation is not affected by C−Ir bond, as the reaction occurred at the C−H bond flanked by the two‐fluorine atoms. All post‐functionalized Ir(III) exhibit red phosphorescence with moderate to good efficiency.