Department of Chemistry, University of Rochester, Rochester, NY 14627, USA.
Science. 2011 Nov 11;334(6057):780-3. doi: 10.1126/science.1211906.
The most common catalyst in the Haber-Bosch process for the hydrogenation of dinitrogen (N(2)) to ammonia (NH(3)) is an iron surface promoted with potassium cations (K(+)), but soluble iron complexes have neither reduced the N-N bond of N(2) to nitride (N(3-)) nor produced large amounts of NH(3) from N(2). We report a molecular iron complex that reacts with N(2) and a potassium reductant to give a complex with two nitrides, which are bound to iron and potassium cations. The product has a Fe(3)N(2) core, implying that three iron atoms cooperate to break the N-N triple bond through a six-electron reduction. The nitride complex reacts with acid and with H(2) to give substantial yields of N(2)-derived ammonia. These reactions, although not yet catalytic, give structural and spectroscopic insight into N(2) cleavage and N-H bond-forming reactions of iron.
在 Haber-Bosch 法中将氮气（N2）氢化生成氨（NH3）的过程中，最常用的催化剂是一种铁表面促进的钾阳离子（K+），但可溶性铁配合物既不能将 N2 的 N-N 键还原为氮化物（N3-），也不能将大量的 N2 转化为 NH3。我们报告了一种分子铁配合物，它可以与 N2 和钾还原剂反应，生成一个含有两个氮化物的配合物，这些氮化物与铁和钾阳离子结合。该产物具有 Fe3N2 核，表明三个铁原子通过六电子还原协同作用打破 N-N 三键。氮化物配合物与酸和 H2 反应，生成大量源自 N2 的氨。这些反应虽然还不是催化反应，但为铁的 N2 裂解和 N-H 键形成反应提供了结构和光谱方面的见解。
