美国乔治敦大学Warren, Timothy H.团队报道了通过亚硝酸盐自由基阴离子，路易斯酸辅助还原亚硝酸盐为一氧化氮和一氧化二氮。相关研究成果于2022年9月5日发表在《自然—化学》。

亚硝酸盐阴离子（NO₂）还原为一氧化氮（NO）、氧化亚氮（N₂O）并最终还原为二氮（N₂）发生在各种环境中，包括作为生物地球化学氮循环的一部分的土壤和酸化核废物中。亚硝酸盐还原通常发生在氧化还原活性过渡金属的配位范围内。

该文中，研究人员表明路易斯酸配位可显著改变该多氧阴离子的还原电位，以使其在非水条件下还原（0.74Vvs NHE）。详细表征证实了硼烷封端的亚硝酸根二阴离子（NO₂^2-）的形成，其具有N（II）氧化态。亚硝酸盐二价离子的质子化导致一氧化氮（NO）的容易损失，而其与NO的反应导致氧化亚氮（N₂O）和亚硝酸盐（NO₂）的歧化。该系统连接了全球氮循环中的三个氧化还原水平，并为NO₂转化为NO提供了基本见解。

附：英文原文

Title: Lewis acid-assisted reduction of nitrite to nitric and nitrous oxides via the elusive nitrite radical dianion

Author: Hosseininasab, Valiallah, DiMucci, Ida M., Ghosh, Pokhraj, Bertke, Jeffery A., Chandrasekharan, Siddarth, Titus, Charles J., Nordlund, Dennis, Freed, Jack H., Lancaster, Kyle M., Warren, Timothy H.

Issue&Volume: 2022-09-05

Abstract: Reduction of nitrite anions (NO2) to nitric oxide (NO), nitrous oxide (N2O) and ultimately dinitrogen (N2) takes place in a variety of environments, including in the soil as part of the biogeochemical nitrogen cycle and in acidified nuclear waste. Nitrite reduction typically takes place within the coordination sphere of a redox-active transition metal. Here we show that Lewis acid coordination can substantially modify the reduction potential of this polyoxoanion to allow for its reduction under non-aqueous conditions (0.74V versus NHE). Detailed characterization confirms the formation of the borane-capped radical nitrite dianion (NO22), which features a N(II) oxidation state. Protonation of the nitrite dianion results in the facile loss of nitric oxide (NO), whereas its reaction with NO results in disproportionation to nitrous oxide (N2O) and nitrite (NO2). This system connects three redox levels in the global nitrogen cycle and provides fundamental insights into the conversion of NO2 to NO.

DOI: 10.1038/s41557-022-01025-9

Source: https://www.nature.com/articles/s41557-022-01025-9