NH3 formation from N2 and H2 mediated by molecular tri-iron complexes
NH3 formation from N2 and H2 mediated by molecular tri-iron complexes
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DOI：
10.1038/s41557-020-0483-7
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发表时间：
2020-06
期刊：
影响因子：
21.8
通讯作者：
Matthias Reiners;D. Baabe;Katharina Münster;Marc-Kevin Zaretzke;M. Freytag;P. Jones;Y. Coppel;S. Bontemps;I. Rosal;L. Maron;Marc D. Walter
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文献类型：
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作者：
Matthias Reiners;D. Baabe;Katharina Münster;Marc-Kevin Zaretzke;M. Freytag;P. Jones;Y. Coppel;S. Bontemps;I. Rosal;L. Maron;Marc D. Walter
生物系统在环境条件下利用固氮酶通过一系列质子化和电子转移步骤将N2还原为氨（NH3）。在化学工业中，Haber-Bosch工艺将N2氢化，但需要高温和高压。这两种方法都依赖于铁基催化剂，但分子铁络合物，促进形成NH3的H2到N2加成仍然很难设计。本文报道了由[Cp ′Fe（μ-I）] 2在N2气氛下还原得到的三铁双氮配合物[（Cp′Fe）3（μ3-N）2]（其中Cp′ = η5- 1，2，4-（Me 3C）3C 5 H2），它由两个μ3-氮配体桥联的三个铁中心组成.在溶液中，该络合物在环境温度（22 °C）和低压（1或4巴）下与H2反应形成NH3。在固态下，通过加入H2（10 bar），通过不寻常的固-气、单晶-单晶转化，它转化为三（铁）双（亚氨基）物种[（Cp′Fe）3（μ3-NH）2]。在溶液中，[（Cp′Fe）3（μ3-NH）2]进一步与H2或H+反应生成NH3。
Living systems carry out the reduction of N2to ammonia (NH3) through a series of protonation and electron transfer steps under ambient conditions using the enzyme nitrogenase. In the chemical industry, the Haber–Bosch process hydrogenates N2but requires high temperatures and pressures. Both processes rely on iron-based catalysts, but molecular iron complexes that promote the formation of NH3on addition of H2to N2have remained difficult to devise. Here, we isolate the tri(iron)bis(nitrido) complex [(Cp′Fe)3(μ3-N)2] (in which Cp′ = η5-1,2,4-(Me3C)3C5H2), which is prepared by reduction of [Cp′Fe(μ-I)]2under an N2atmosphere and comprises three iron centres bridged by two μ3-nitrido ligands. In solution, this complex reacts with H2at ambient temperature (22 °C) and low pressure (1 or 4 bar) to form NH3. In the solid state, it is converted into the tri(iron)bis(imido) species, [(Cp′Fe)3(μ3-NH)2], by addition of H2(10 bar) through an unusual solid–gas, single-crystal-to-single-crystal transformation. In solution, [(Cp′Fe)3(μ3-NH)2] further reacts with H2or H+to form NH3.