Department of Chemistry, Georgetown University, Box 571227, Washington, DC, 20057-1227, USA.
Department of Chemistry, Marquette University, P.O. Box 1881, Milwaukee, WI, 53201-1881, USA.
Angew Chem Int Ed Engl. 2020 Jun 26;59(27):10854-10858. doi: 10.1002/anie.202001450. Epub 2020 Apr 17.
S-Nitrosothiols (RSNOs) serve as air-stable reservoirs for nitric oxide in biology. While copper enzymes promote NO release from RSNOs by serving as Lewis acids for intramolecular electron-transfer, redox-innocent Lewis acids separate these two functions to reveal the effect of coordination on structure and reactivity. The synthetic Lewis acid B(C F ) coordinates to the RSNO oxygen atom, leading to profound changes in the RSNO electronic structure and reactivity. Although RSNOs possess relatively negative reduction potentials, B(C F ) coordination increases their reduction potential by over 1 V into the physiologically accessible +0.1 V vs. NHE. Outer-sphere chemical reduction gives the Lewis acid stabilized hyponitrite dianion trans-[LA-O-N=N-O-LA] [LA=B(C F ) ], which releases N O upon acidification. Mechanistic and computational studies support initial reduction to the [RSNO-B(C F ) ] radical anion, which is susceptible to N-N coupling prior to loss of RSSR.
S-亚硝基硫醇（RSNOs）作为一氧化氮在生物学中的稳定储存库。虽然铜酶通过充当分子内电子转移的路易斯酸来促进 RSNO 中 NO 的释放，但氧化还原惰性路易斯酸将这两种功能分开，以揭示配位对结构和反应性的影响。合成路易斯酸 B(C F )与 RSNO 的氧原子配位，导致 RSNO 电子结构和反应性发生深刻变化。尽管 RSNO 具有相对负的还原电位，但 B(C F )的配位使它们的还原电位增加了超过 1V，进入生理上可及的+0.1V 相对于 NHE。外球化学还原给出路易斯酸稳定的低亚硝酸盐二阴离子反式-[LA-O-N=N-O-LA] [LA=B(C F ) ]，在酸化时释放 NO。机理和计算研究支持初始还原为[RSNO-B(C F ) ]自由基阴离子，该阴离子在 RSSR 丢失之前易发生 N-N 偶联。
