Nakanishi Kazuki, Jimenez-Halla J Oscar C, Yamazoe Seiji, Nakamoto Masaaki, Shang Rong, Yamamoto Yohsuke
Department of Chemistry, Graduate School of Advanced Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan.
Department of Chemistry, Division of Natural and Exact Sciences, University of Guanajuato, Campus Gto, Noria Alta s/n, 36050 Guanajuato, Mexico.
Inorg Chem. 2021 Jul 5;60(13):9970-9976. doi: 10.1021/acs.inorgchem.1c01236. Epub 2021 Jun 22.
Meridional tridentate N-heterocyclic carbene (NHC)-based pincer ligands contribute to a substantial growth in modern organometallic chemistry in both homogeneous catalysis and luminescence materials. Among all NHC-based pincer ligands, the dianionic LX-type CCC-pincer ones constitute the smallest subcategory owing to their limited ligand frameworks suitable for complexation. This work reports a one-pot, high-yield synthesis of a homoleptic anionic all-carbon bis-pincer iridium(III) complex () directly from a bis(aryl)-substituted dipyrido-annulated (dpa) imidazolium salt and [Ir(COD)Cl] via a cascade of deprotonation/C-H activation processes. Both experimental complexation chemistry and computational mechanistic investigation suggest that the large bite angle and π-rich character of the dpa NHC are responsible for its facile complexation as a dianionic LX-type CCC-pincer ligand precursor. The all-carbon ligated iridium(III) complex () bearing a π-conjugated ligand scaffold showed remarkably low oxidation potentials, which allows future investigations in its redox chemistry and photophysical properties.
基于子午线三齿氮杂环卡宾（NHC）的钳形配体在均相催化和发光材料这两个领域极大地推动了现代有机金属化学的发展。在所有基于NHC的钳形配体中，二价阴离子LX型CCC-钳形配体由于其适合络合的配体框架有限，构成了最小的子类。这项工作报道了一种通过去质子化/C-H活化过程的级联反应，直接从双（芳基）取代的二吡啶并环化（dpa）咪唑盐和[Ir(COD)Cl]一锅高产率合成同配阴离子全碳双钳形铱（III）配合物（）。实验络合化学和计算机理研究均表明，dpa NHC的大咬角和富π特性使其作为二价阴离子LX型CCC-钳形配体前体易于络合。带有π共轭配体支架的全碳连接铱（III）配合物（）显示出极低的氧化电位，这为其氧化还原化学和光物理性质的未来研究提供了可能。
