氮化铁是生物固氮和工业 Haber-Bosch 过程中的关键中间体,用于从二氮中形成氨。然而,所提出的将氮化物连续转化为氨的方法仍然难以实现。在这方面,长期以来,寻找描述良好的多铁氮化物模型配合物以及控制其对氨形成的反应性的研究一直具有巨大的挑战和重要性。在这里,我们报告了一个定义明确的硫醇盐桥接的 Fe IV Fe IV μ-亚硝基络合物,具有不常见的弯曲 Fe-N-Fe 部分。值得注意的是,该络合物对 H 2氢化反应表现出优异的反应性在环境条件下,以高产率形成氨。结合实验和计算研究表明,硫醇桥接的 Fe III Fe III μ-氨基络合物是关键中间体,它是通过 H 2的异常双电子氧化产生的。此外,通过用电子和水作为质子源处理这种二铁μ-氮化物,也实现了氨的生产。
Mechanism of proton transfer to coordinated thiolates: encapsulation of acid stabilizes precursor intermediate
作者:Ahmed Alwaaly、William Clegg、Ross W. Harrington、Athinoula L. Petrou、Richard A. Henderson
DOI:10.1039/c5dt01716e
日期:——
Hydrogen bonded intermediate in protonation of [Ni(thiolate)(triphos)]+ by 2,6-lutidinium is stabilized by encapsulation of the acid by phenyl groups of triphos.
Testing the Polynuclear Hypothesis: Multielectron Reduction of Small Molecules by Triiron Reaction Sites
作者:Tamara M. Powers、Theodore A. Betley
DOI:10.1021/ja405057n
日期:2013.8.21
protonation of the anionic triiron nitrido with lutidinium tetraphenylborate. Deprotonation of the triiron parent imido ((tbs)L)Fe3(μ(3)-NH) with lithium bis(trimethylsilyl)amide results in regeneration of the triiron nitrido complex capped with a thf-solvated Li cation [((tbs)L)Fe3(μ(3)-N)]Li(thf)3. The lithium capped nitrido, structurally similar to the pseudo C3-symmetric triiron nitride with a tetrabutylammonium
Haber–Bosch process, which requires extreme temperatures and pressures to activatedinitrogen. Biological fixation occurs through dinitrogen and reduced NxHy species at multi-iron centres of compounds bearing sulfur ligands, but it is difficult to elucidate the mechanistic details and to obtain stable model intermediate complexes for further investigation. Metal-based synthetic models have been applied
尽管固氮酶通常在环境温度和压力下将分子氮转化为氨,但该反应目前在工业上使用 Haber-Bosch 工艺进行,该工艺需要极端温度和压力来激活二氮。生物固定通过二氮和还原的 N x H y 发生含硫配体化合物的多铁中心的物种,但难以阐明机理细节并获得稳定的模型中间体配合物以供进一步研究。尽管大多数模型都涉及单核系统,但已应用基于金属的合成模型来揭示部分细节。在这里,我们报告了由二齿硫醇盐配体桥接的二铁络合物,可以容纳 HN = NH。在还原和质子化之后,HN=NH通过由 N 2 H 3 –和 NH 2 –桥接的关键中间复合物转化为 NH 3物种。值得注意的是,最终的氨释放受水作为质子源的影响。进行了密度泛函理论计算,提出了生物固氮途径。
Proton Transfer to Nickel−Thiolate Complexes. 2. Rate-Limiting Intramolecular Proton Transfer in the Reactions of [Ni(SC<sub>6</sub>H<sub>4</sub>R-4)(PhP{CH<sub>2</sub>CH<sub>2</sub>PPh<sub>2</sub>}<sub>2</sub>)]<sup>+</sup> (R = NO<sub>2</sub>, Cl, H, Me, or MeO)
作者:Valerie Autissier、Pedro Martin Zarza、Athinoula Petrou、Richard A. Henderson、Ross W. Harrington、William C. Clegg
DOI:10.1021/ic0303237
日期:2004.5.1
of [Ni(SC(6)H(4)R-4)(triphos)](+) (triphos = PhP[CH(2)CH(2)PPh(2)](2); R = NO(2), Cl, H, Me, or MeO) by [lutH](+) (lut = 2,6-dimethylpyridine) to form [Ni(S(H)C(6)H(4)R-4)(triphos)](2+) is an equilibrium reaction in MeCN. Kinetic studies, using stopped-flow spectrophotometry, reveal that the reactionsoccur by a two-step mechanism. Initially, [lutH](+) rapidly binds to the complex (K(2)(R)) in an interaction
[Ni(SC(6)H(4)R-4)(triphos)](+)的质子化(triphos = PhP [CH(2)CH(2)PPh(2)](2); R = NO (2),Cl,H,Me或MeO)由[lutH](+)(lut = 2,6-二甲基吡啶)形成[Ni(S(H)C(6)H(4)R-4) (triphos)](2+)是MeCN中的平衡反应。使用停止流分光光度法的动力学研究表明,反应是通过两步机理进行的。最初,[lutH](+)在相互作用中迅速结合到配合物(K(2)(R))上,这种相互作用可能涉及酸与硫的氢键结合。由于电子和空间因素,随后分子内质子从[lutH](+)转移到硫(k(3)(R))的速度很慢。[Ni(SC(6)H(4)R-4)(triphos)](+)的X射线晶体结构(R = NO(2),H,Me或MeO)显示所有描述都最好作为方平面复合体,三价配体的苯基取代基对空间上要求硫的[
Diiron oxo reactivity in a weak-field environment
作者:Elizabeth J. Johnson、Claudia Kleinlein、Rebecca A. Musgrave、Theodore A. Betley
DOI:10.1039/c9sc00605b
日期:——
tBudmx)Fe2(Mes)2. Treatment of ( tBudmx)Fe2(Mes)2 with one equivalent of water yields the diiron μ-oxo complex ( tBudmx)Fe2(μ-O) and free mesitylene. A two-electron oxidation of ( tBudmx)Fe2(μ-O) gives rise to the diferric complex ( tBudmx)Fe2(μ-O)Cl2, and one-electron reduction from this FeIIIFeIII state allows for isolation of a mixed-valent species [Cp2Co][( tBudmx)Fe2(μ-O)Cl2]. Both ( tBudmx)Fe2(μ-O) and