Unsaturated Iridium(III) Complexes Supported by a Quinolato鈥揅arboxylato ONO Pincer-Type Ligand: Synthesis, Reactivity, and Catalytic C鈥揌 Functionalization

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• 作者：Duc Hanh Nguyen ; Jes煤s J. P茅rez-Torrente ; M. Victoria Jim茅nez ; F. Javier Modrego ; Daniel G贸mez-Bautista ; Fernando J. Lahoz ; Luis A. Oro
• 刊名：Organometallics
• 出版年：2013
• 出版时间：December 9, 2013
• 年：2013
• 卷：32
• 期：23
• 页码：6918-6930
• 全文大小：517K
• 年卷期：v.32,no.23(December 9, 2013)
• ISSN：1520-6041

文摘

The unsaturated 蟽,蟺-cyclooctenyl iridium(III) pincer compound [Ir(魏³-hqca)(1-魏-4,5-畏-C₈H₁₃)] (1) has been prepared by the reaction of [Ir(cod)(CH₃CN)₂]BF₄ with lithium 8-oxidoquinoline-2-carboxylate (Li₂hqca) and obtained as two isomers derived from the relative disposition of the pincer and the 蟽,蟺-cyclooctenyl ligands. Compound 1 can be prepared as a single isomer by reaction of 8-hydroxyquinoline-2-carboxylic acid (H₂hqca) with [Ir(渭-OMe)(cod)]₂. Reaction of [Ir(渭-OH)(coe)₂]₂ with H₂hqca gave the square-pyramidal iridum(III) complex [IrH(魏³-hqca)(coe)] (3). This compound exists as dinuclear assemblies [IrH(魏³-hqca)(coe)]₂ in noncoordinating solvents and as the corresponding labile mononuclear solvates in more polar solvent solutions. The dimerization of 3 was established by ¹H-DOSY NMR spectroscopy and an ESI⁺ mass spectrum and supported by DFT calculations. Reaction of 3 with pyridine gave the adduct [IrH(魏³-hqca)(coe)(py)] (4) and the bis-pyridine complexes [IrH(魏³-hqca)(R-py)₂] (R = H (6), 2-Me (7)) by replacement of the coe ligand. Compound 4 was transformed into the bromo derivative [IrBr(魏³-hqca)(coe)(py)] (5) by reaction with N-bromosuccinimide. Carbonylation of 4 gave the cyclooctenyl complex [Ir(魏³-hqca)(1-魏-C₈H₁₅)(CO)(py)] (8), which is stable only under a carbon monoxide atmosphere. The pincer complexes were active in the catalytic borylation of arenes under thermal conditions.