The role of bridging ligands in dinitrogen reduction and functionalization by uranium multimetallic complexes
The role of bridging ligands in dinitrogen reduction and functionalization by uranium multimetallic complexes
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DOI：
10.1038/s41557-018-0167-8
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发表时间：
2019-02-01
期刊：
影响因子：
21.8
通讯作者：
Mazzanti, Marinella
中科院分区：
文献类型：
--
作者：
Falcone, Marta;Barluzzi, Luciano;Mazzanti, Marinella
金属中心之间的协同性被认为是工业哈伯-博施过程和固氮酶自然固氮过程中二氮还原的关键步骤，但N-2还原的机制仍然知之甚少。这在很大程度上是因为在不存在强碱还原剂的情况下还原和官能化二氮的多金属络合物对于建立结构-活性关系至关重要，但仍然非常罕见。最近，我们报道了一种多金属氮化物桥连的二铀（III）配合物，能够还原和功能化二氮。在这里，我们表明，一个类似的配合物组装的氧代，而不是一个氮化物链接也影响四电子还原的二氮，但所得的氧代-（N-2）复合物的反应性显着不同的氮化物-（N-2）。计算研究表明，一个不同的键合方案的二氮，其中的桥接氮化物不参与N-2的绑定和随后的激活，而氧化物不。
Cooperativity between metal centres is identified as a crucial step in dinitrogen reduction both for the industrial Haber-Bosch process and for the natural fixation of nitrogen by nitrogenase enzymes, but the mechanism of N-2 reduction remains poorly understood. This is in large part because multimetallic complexes that reduce and functionalize dinitrogen in the absence of strong alkali reducing agents are crucial to establish a structure-activity relationship, but remain extremely rare. Recently, we reported a multimetallic nitride-bridged diuranium(III) complex capable of reducing and functionalizing dinitrogen. Here we show that an analogous complex assembled with an oxo instead of a nitride linker also effects the four-electron reduction of dinitrogen, but the reactivity of the resulting oxo-(N-2) complex differs significantly from that of the nitride-(N-2). Computational studies show a different bonding scheme for the dinitrogen where the bridging nitride does participate in the binding and consequent activation of N-2, while the oxide does not.