A Peroxynitrite Dicopper Complex: Formation via Cu–NO and Cu–O 2 Intermediates and Reactivity via O–O Cleavage Chemistry

作者：Rui Cao, L.T. Elrod, Ryan L. Lehane, Eunsuk Kim, Kenneth D. Karlin · 发表于：Journal of the American Chemical Society · 年份：2016 · DOI：10.1021/jacs.6b10689 · 被引用次数：31 · 研究领域：Nitric Oxide and Endothelin Effects、Metal-Catalyzed Oxygenation Mechanisms、Metal complexes synthesis and properties

A mixed-valent Cu(I)Cu(II) complex, [Cu I,II 2 (UN-O – )] 2+ ( 1 ), reacts with NO (g) at −80 °C to form [Cu I,II 2 (UN-O – )(NO)] 2+ ( 2 ), best described as a mixed-valent nitrosyl complex that has a ν(N–O) band at 1670 cm –1 in its infrared (IR) spectrum. Complex 2 undertakes a one-electron oxidation via the addition of O 2(g) to generate a new intermediate, best described as a superoxide and nitrosyl adduct, [Cu II 2 (UN-O – )(NO)(O 2 – )] 2+ ( 3 ), based on its distinctively blue-shifted ν(N–O) band at 1853 cm –1 . Over the course of 20 min at −80 °C, 3 is converted to the peroxynitrite (PN) complex [Cu II 2 (UN-O – )( − OON═O)] 2+ ( 4 ), which was characterized by low-temperature electrospray ionization mass spectrometry (ESI-MS) and IR spectroscopy; ν(N–O) absorptions at 1520 and 1640 cm –1 have been assigned as cis - and trans -conformers of the PN ligand in 4 . Alternatively, the superoxide complex [Cu II 2 (UN-O – )(O 2 •– )] 2+ ( 5 ) is found to react with NO (g) to generate the same intermediate superoxide and nitrosyl adduct 3 (based on IR criteria), which likewise converts to the same PN complex 4 . The O–O bond in 4 undergoes heterolysis in dichloromethane solvent and is postulated to produce nitronium ion, leading to ortho -nitration of 2,4-di- tert -butylphenol (DTBP). However, in 2-methyltetrahydrofuran as solvent, the O–O bond undergoes homolysis to generate • NO 2 (detected spectrophotometrically) and a putative higher-valent complex, [Cu II,III 2 (UN-O – ...