Department of Chemistry , Indian Institute of Engineering Science and Technology , Shibpur Botanic Garden, Howrah 711103 , India.
Homogeneous Catalysis Group, van't Hoff Institute for Molecular Sciences , University of Amsterdam , Science Park 904 , 1098 XH Amsterdam , The Netherlands.
Inorg Chem. 2019 Feb 4;58(3):1935-1948. doi: 10.1021/acs.inorgchem.8b02877. Epub 2019 Jan 14.
Iron catalyzed carbon-nitrogen bond formation reactions of a wide variety of nucleophiles and aryl halides using well-defined iron-complexes featuring redox noninnocent 2-(arylazo)-1,10-phenanthroline (L) ligands are reported. Besides substrate centered C-N coupling, C-N bond formation reactions were also observed at the ortho- and para-positions of the phenyl ring of the coordinated azo-aromatic scaffolds affording new tetradentate ligands, 2-N-aryl-(2-arylazo)-1,10-phenanthroline (L), and tridentate ligands, 4 -N-aryl-(2-arylazo)-1,10-phenanthroline (L), respectively. Control experiments and mechanistic studies reveal that the complex [FeLCl] (1) undergoes in situ reduction during the catalytic reaction to produce the monoanionic complex [1], which then acts as the active catalyst. The metal (iron) and the coordinated ligand were found to work in a cooperative manner during the transfer processes involved in the fundamental steps of the catalytic cycle. Detailed experimental and theoretical (DFT) studies were performed to get insight into the competitive substrate versus ligand centered amination reactions.
本文报道了使用具有氧化还原非中性 2-(芳基偶氮)-1,10-菲咯啉 (L) 配体的定义明确的铁配合物，实现了各种亲核试剂和芳基卤化物的铁催化碳-氮键形成反应。除了以底物为中心的 C-N 偶联反应外，在配位偶氮芳环的苯基环的邻位和对位也观察到 C-N 键形成反应，分别得到新的四齿配体 2-N-芳基-(2-芳基偶氮)-1,10-菲咯啉 (L) 和三齿配体 4-N-芳基-(2-芳基偶氮)-1,10-菲咯啉 (L)。控制实验和机理研究表明，配合物 [FeLCl]（1）在催化反应过程中发生原位还原，生成单阴离子配合物 [1]，然后作为活性催化剂。在催化循环的基本步骤中所涉及的转移过程中，发现金属（铁）和配位配体以协同方式起作用。进行了详细的实验和理论（DFT）研究，以深入了解竞争性底物与配体为中心的胺化反应。
