A Synthetic Single-Site Fe Nitrogenase: High Turnover, Freeze-Quench (57)Fe Mössbauer Data, and a Hydride Resting State.
A Synthetic Single-Site Fe Nitrogenase: High Turnover, Freeze-Quench (57)Fe Mössbauer Data, and a Hydride Resting State.
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合成单位Fe氮酶：高离职率，冻结（57）feMössbauer数据和氢化物静止状态。
DOI：
10.1021/jacs.6b01706
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发表时间：
2016-04-27
影响因子：
15
通讯作者：
Peters JC
中科院分区：
文献类型：
--
作者：
Del Castillo TJ;Thompson NB;Peters JC
少数已知的分子固氮系统，包括固氮酶的机制，是非常感兴趣的，但没有完全理解。我们最近报道了四齿P3 E配体（E = B，C）的Fe-N_2配合物在N_2气氛下与酸和还原剂在低温下催化生成NH_3。在这里，我们表明，这些铁催化剂是出乎意料的强大，并保留多次重新加载后的活性。通过用高度纯化的酸增加酸/还原剂负载，已经实现了每种Fe催化剂的NH3产率的几乎一个数量级的提高（对于P3 B，每Fe产生高达64当量的NH3，对于P3 C，每Fe产生高达47当量的NH3）。循环伏安法显示在P3 BFe-N2/P3 BFe-N2 −电对处催化的明显开始，并且在−45 °C下P3 BFe+的控制电位电解表明电解N2还原为NH3是可行的。动力学研究揭示了一阶速率依赖于Fe催化剂浓度（P3 B），与单中心催化剂模型一致。一个isostructural系统（P3 Si）被证明是明显更有选择性的析氢。原位冻结淬火穆斯堡尔谱在营业额揭示了铁硼氢化物复合物作为一个可能的休息状态的P3 BFe催化剂系统。我们假设HER活性可以防止氢化铁的形成毒害P3 BFe-系统。这个想法可能是重要的合成固氮酶的设计考虑，也可能有更广泛的意义，中间金属离子和氢的演变可能在生物固氮中发挥关键作用。
The mechanisms of the few known molecular nitrogen-fixing systems, including nitrogenase enzymes, are of much interest but are not fully understood. We recently reported that Fe-N2 complexes of tetradentate P3E ligands (E = B, C) generate catalytic yields of NH3 under an atmosphere of N2 with acid and reductant at low temperatures. Here we show that these Fe catalysts are unexpectedly robust and retain activity after multiple reloadings. Nearly an order of magnitude improvement in yield of NH3 for each Fe catalyst has been realized (up to 64 equiv NH3 produced per Fe for P3B and up to 47 equiv for P3C) by increasing acid/reductant loading with highly purified acid. Cyclic voltammetry shows the apparent onset of catalysis at the P3BFe-N2/P3BFe-N2− couple and controlled-potential electrolysis of P3BFe+ at −45 °C demonstrates that electrolytic N2 reduction to NH3 is feasible. Kinetic studies reveal first-order rate dependence on Fe catalyst concentration (P3B), consistent with a single-site catalyst model. An isostructural system (P3Si) is shown to be appreciably more selective for hydrogen evolution. In situ freeze-quench Mössbauer spectroscopy during turnover reveals an iron-borohydrido-hydride complex as a likely resting state of the P3BFe-catalyst system. We postulate that HER activity may prevent iron hydride formation from poisoning the P3BFe-system. This idea may be important to consider in the design of synthetic nitrogenases and may also have broader significance given that intermediate metal-hydrides and hydrogen evolution may play a key role in biological nitrogen fixation.
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影响因子：
15
作者：
Daifuku SL;Kneebone JL;Snyder BE;Neidig ML
通讯作者：
Neidig ML
影响因子：
4.9
作者：
Field, Leslie D.;Li, Hsiu L.;Turner, Peter
通讯作者：
Turner, Peter
影响因子：
15
作者：
Grubel, Katarzyna;Brennessel, William W.;Mercado, Brandon Q.;Holland, Patrick L.
通讯作者：
Holland, Patrick L.
影响因子：
62.1
作者：
Hoffman, Brian M.;Lukoyanov, Dmitriy;Yang, Zhi-Yong;Dean, Dennis R.;Seefeldt, Lance C.
通讯作者：
Seefeldt, Lance C.
影响因子：
46.2
作者：
CHATT, J;LEIGH, GJ
通讯作者：
LEIGH, GJ