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Acid-induced conversion of nitrite to nitric oxide at the copper(ii) center: a new catalytic pathway

Bhardwaj, P and Kulbir, N and Devi, T and Kumar, P (2023) Acid-induced conversion of nitrite to nitric oxide at the copper(ii) center: a new catalytic pathway. In: Inorganic Chemistry Frontiers .

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Official URL: https://doi.org/10.1039/d3qi01637d


Acid-induced reduction of nitrites (NO2�) to nitric oxide (NO) at Cu/Fe centers is one of the key steps in the nitrogen cycle and serves as an essential path to NO generation. In this study, we report the acid-catalysed conversion of NO2� to NO at the CuII centers in CuII-nitrito complexes, (Me2BPMEN)CuII(NO2�)+ (1) and (H2BPMEN)CuII(NO2�)+ (2). Both the CuII-NO2� complexes showed the formation of NO(g) along with H2O2 when reacted with one equivalent acid (H+) via the N-O bond homolysis of the presumed CuII-nitrous acid (Cu-ONOH2+) intermediate. However, the H2O2 amount decreased with time or an increase in H+ and completely disappeared when H+ was more than about two equivalents accompanied by the generation of H2O. We detected the released NO(g) by using headspace gas chromatography/mass spectrometry; moreover, the NO(g) evolution was confirmed by the formation of a significant amount of {CoNO}8, (12-TMC)Co(NO)2+ up to (90 ± 5%) in the above reactions. Mechanistic investigations using 15N-labeled-15NO2� and 18O-labeled-16O14N18O� revealed that the N-atom in NO is derived from the 18ONO� ligand, which was further confirmed by the detection of 15NO and N18O gas in headspace gas chromatography/mass spectrometry. We also monitored and characterized the formation of H2O2 (one equivalent of H+) and H2O (two equivalents of H+) and the results describe the rationale behind biological NO2� reduction reactions generating NO along with H2O. We observed more than 90% recovery of (1) after 10 catalytic cycles of NO(g) generation. © 2023 The Royal Society of Chemistry.

Item Type: Journal Article
Publication: Inorganic Chemistry Frontiers
Publisher: Royal Society of Chemistry
Additional Information: The copyright for this article belongs to Author.
Keywords: Copper compounds; Gas chromatography; Nitrogen oxides; Reduction; Spectrometry, reductions; Acid-catalyzed conversions; Catalytic cycles; Catalytic pathways; Headspace gas chromatography-mass spectrometry; Homolysis; Mechanistics; Nitrogen cycles; Nitrous acid; Reduction reaction, Nitric oxide
Department/Centre: Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited: 24 Apr 2024 10:21
Last Modified: 24 Apr 2024 10:21
URI: https://eprints.iisc.ac.in/id/eprint/84347

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