Department Chemie, Technische Universität München, Lichtenbergstr. 4, 85748 Garching b. München, Germany.
Nat Chem. 2011 May 22;3(7):532-7. doi: 10.1038/nchem.1051.
Bioinspired hydrogenation of N(2) to ammonia at ambient conditions by stepwise nitrogen protonation/reduction with metal complexes in solution has experienced remarkable progress. In contrast, the highly desirable direct hydrogenation with H(2) remains difficult. In analogy to the heterogeneously catalysed Haber-Bosch process, such a reaction is conceivable via metal-centred N(2) splitting and unprecedented hydrogenolysis of the nitrido ligands to ammonia. We report the synthesis of a ruthenium(IV) nitrido complex. The high nucleophilicity of the nitrido ligand is demonstrated by unusual N-C coupling with π-acidic CO. Furthermore, the terminal nitrido ligand undergoes facile hydrogenolysis with H(2) at ambient conditions to produce ammonia in high yield. Kinetic and quantum chemical examinations of this reaction suggest cooperative behaviour of a phosphorus-nitrogen-phosphorus pincer ligand in rate-determining heterolytic hydrogen splitting.
受生物启发，在溶液中通过分步氮质子化/还原作用，使用金属配合物在环境条件下将 N(2)氢化生成氨取得了显著进展。相比之下，用 H(2)进行直接氢化仍然很困难。类似于非均相催化的哈伯-博斯（Haber-Bosch）工艺，通过金属中心的 N(2)裂解和前所未有的氮化物配体氢解为氨，可以设想这种反应。我们报告了一种钌(IV)氮化物配合物的合成。氮化物配体的高亲核性通过与π-酸性 CO 的不寻常 N-C 偶联得到证明。此外，末端氮化物配体在环境条件下容易与 H(2)发生氢解反应，以高产率生成氨。对该反应的动力学和量子化学研究表明，磷-氮-磷三齿配体在决定速率的异裂氢裂解中表现出协同行为。
