| Autor: |
Cao R; Department of Chemistry, Johns Hopkins University , Baltimore, Maryland 21218, United States., Elrod LT; Department of Chemistry, Brown University , Providence, Rhode Island 02912, United States., Lehane RL; Department of Chemistry, Brown University , Providence, Rhode Island 02912, United States., Kim E; Department of Chemistry, Brown University , Providence, Rhode Island 02912, United States., Karlin KD; Department of Chemistry, Johns Hopkins University , Baltimore, Maryland 21218, United States. |
| Jazyk: |
angličtina |
| Zdroj: |
Journal of the American Chemical Society [J Am Chem Soc] 2016 Dec 14; Vol. 138 (49), pp. 16148-16158. Date of Electronic Publication: 2016 Dec 02. |
| DOI: |
10.1021/jacs.6b10689 |
| Abstrakt: |
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 - )(O 2- )] 2+ , that abstracts a H-atom from DTBP to give [Cu II 2 (UN-O - )(OH)] 2+ and a phenoxyl radical. The latter may dimerize to form the bis-phenol observed experimentally or couple with the • NO 2 present, leading to o-phenol nitration. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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