Chang Hao-Ching, Lin Yen-Hao, Werlé Christophe, Neese Frank, Lee Way-Zen, Bill Eckhard, Ye Shengfa
Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany.
Department of Chemistry, National Taiwan Normal University, 88, Ting-chou Rd. Sec. 4, 11677, Taipei, Taiwan.
Angew Chem Int Ed Engl. 2019 Dec 2;58(49):17589-17593. doi: 10.1002/anie.201908689. Epub 2019 Oct 22.
Terminal metal nitrides have been proposed as key intermediates in a series of pivotal chemical transformations. However, exploring the chemical activity of transient tetragonal iron(V) nitrides is largely impeded by their facile dimerization in fluid solutions. Herein, in situ EPR and Mössbauer investigations are presented of unprecedented oxygenation of a paramagnetic iron(V) nitrido intermediate, [Fe N(cyclam-ac)] (2, cyclam-ac =1,4,8,11-tetraazacyclotetradecane-1-acetate anion), yielding an iron nitrosyl complex, [Fe(NO)(cyclam-ac)] (3). Further theoretical studies suggest that during the reaction a closed-shell singlet O atom is transferred to 2. Consequently, the N-O bond formation does not follow a radical coupling mechanism proposed for the N-N bond formation but is accomplished by three mutual electron-transfer pathways between 2 and the O atom donor, thanks to the ambiphilic nature of 2.
末端金属氮化物已被认为是一系列关键化学转化中的关键中间体。然而，探索瞬态四方铁（V）氮化物的化学活性在很大程度上受到其在流体溶液中容易二聚的阻碍。在此，对顺磁性铁（V）氮化物中间体[Fe N(cyclam-ac)]（2，cyclam-ac = 1,4,8,11-四氮杂环十四烷-1-乙酸根阴离子）前所未有的氧化反应进行了原位电子顺磁共振（EPR）和穆斯堡尔谱研究，生成了一种亚硝酰铁配合物[Fe(NO)(cyclam-ac)]（3）。进一步的理论研究表明，在反应过程中，一个闭壳单重态氧原子转移到了2上。因此，N-O键的形成并不遵循为N-N键形成所提出的自由基偶联机制，而是由于2的双亲性，通过2与氧原子供体之间的三条相互电子转移途径完成的。
