Luminescent Iridium(III) Complexes Supported by N-Heterocyclic Carbene-based C^C^C-Pincer Ligands and Aromatic Diimines

摘要: Iridium(III) hydrido complexes containing N-heterocyclic carbene (NHC)-based pincer ligand 1,3-bis(1-butylimidazolin-2-ylidene)phenyl anion (C1^C^C1) or 1,3-bis(3-butylbenzimidazolin-2-ylidene)phenyl (C2^C^C2) and aromatic diimine (2,2′-bipyridine (bpy), 1,10-phenanthroline (phen), 4,4′-dimethyl-2,2′-bipyridine (Me2bpy), dipyrido-[3,2-f:2′,3′-h]-quinoxaline (dpq)) in the form of [Ir(C^C^C)(N^N)(H)]+ have been prepared. Crystal structures for these show that Ir–CNHC distances are 2.043(5)–2.056(5) A. The hydride chemical shifts bearing C1^C^C1 (−20.6 to −20.3 ppm) more upfield than those with C2^C^C2 (−19.5 −19.2 ppm), revealing is a better electron donor C2^C^C2. Spectroscopic comparisons time-dependent density functional theory (TD-DFT) calculations suggest lowest-energy electronic transition associated (λ = 340–530 nm (e ≤ 103 dm3 mol−1 cm−1)) originate from dπ(IrIII) → π*(N^N) metal-to-ligand charge transfer transition, where dπ(IrIII) level contain significant contribution C^C^C ligands. All emissive yellow-spectral region (553–604 nm CH3CN CH2Cl2) upon photo-excitation quantum yields 10−3–10−1.