Controlling O 2 Reactivity in Synthetic Analogues of [NiFeS]- and [NiFeSe]-Hydrogenase Active Sites
Controlling O 2 Reactivity in Synthetic Analogues of [NiFeS]- and [NiFeSe]-Hydrogenase Active Sites
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控制[NiFeS]-和[NiFeSe]-氢化酶活性位点的合成类似物中的O 2 反应性
DOI：
10.1021/jacs.9b07448
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发表时间：
2019
影响因子：
15
通讯作者：
Darensbourg, Marcetta Y.
中科院分区：
文献类型：
--
作者：
Yang, Xuemei;Elrod, Lindy C.;Le, Trung;Vega, Valeria S.;Naumann, Haley;Rezenom, Yohannes;Reibenspies, Joseph H.;Hall, Michael B.;Darensbourg, Marcetta Y.
限制或逆转空气敏感性贱金属析氢/氧化反应催化剂在与外源O2接触时的降解的策略是由自然界对氢化酶活性位点的设计指导的。在[NiFeS]-和[NiFeSe]-H2 ase中，氧对硫和硒的亲和力在有氧条件下产生含氧硫族元素，并通过保持NiFe核心结构来延迟金属处的不可逆氧损伤。为了确定S位氧吸收的控制特征，通过对μ-EPhX（X = CF 3，Cl，H，OMe，NMe 2）上对位取代基的电子调谐，比较了Ni（μ-EPhX）（μ-S′N2）Fe（E = S或Se，Fe=（η5-C5 H5）FeII（CO））配合物中Ni和Fe之间的通讯.硫族元素的单氧和双氧吸收导致四元环核Ni（μ-EPhX）（μ-S′N2）Fe转化为五元环Ni-O-E-Fe-S′，其中O原子插入E和Ni之间。在E = S，X = NMe 2的情况下，分离出了双氧吸收络合物，并将其表征为亚磺酸根物种，其中O2 SPh-NMe 2单元的第二个O指向五元Ni-O-S-Fe-S′环。反应的定性速率和吸氧产物的比率与EPhX上X取代基的Hammett参数相关。密度泛函理论的计算结果支持所观察到的NiFe核心反应性的远程效应;在SPhX系列中，电子越丰富的硫越具有O2响应性;硒类似物与O2的反应性甚至更高。使用18 O2/16 O2混合物对亚磺酸盐产物进行质谱分析，表明O2加成的协同机理。脱氧，还原或O原子提取试剂，发生1-O加成配合物，而2-O，亚磺酸，类似物是惰性的。从1-O亚磺酸根物种中提取氧与可溶性NAD+还原[NiFe]-H2酶中的氧修复有关（Horch，M.;劳特巴赫;等人，J. Am. 2015，137，2555-2564）。
Strategies for limiting, or reversing, the degradation of air-sensitive, base metal catalysts for the hydrogen evolution/oxidation reaction on contact with adventitious O2are guided by nature′s design of hydrogenase active sites. The affinity of oxygen for sulfur and selenium, in [NiFeS]- and [NiFeSe]-H2ase, yields oxygenated chalcogens under aerobic conditions, and delays irreversible oxygen damage at the metals by maintaining the NiFe core structures. To identify the controlling features of S-site oxygen uptake, relatedNi(μ-EPhX)(μ-S′N2)Fe(E = S or Se,Fe= (η5-C5H5)FeII(CO)) complexes were electronically tuned by the para-substituent on μ-EPhX (X = CF3, Cl, H, OMe, NMe2) and compared in aspects of communication between Ni and Fe. Both single and double O atom uptake at the chalcogens led to the conversion of the four-membered ring core,Ni(μ-EPhX)(μ-S′N2)Fe, to a five-membered ring Ni–O–E–Fe–S′, where an O atom inserts between E and Ni. In the E = S, X = NMe2case, the two-oxygen uptake complex was isolated and characterized as the sulfinato species with the second O of the O2SPh-NMe2unit pointing out of the five-membered Ni–O–S–Fe–S′ ring. Qualitative rates of reaction and ratios of oxygen-uptake products correlate with Hammett parameters of the X substituent on EPhX. Density functional theory computational results support the observed remote effects on the NiFe core reactivity; the more electron-rich sulfurs are more O2responsive in the SPhXseries; the selenium analogues were even more reactive with O2. Mass spectral analysis of the sulfinato products using a mixture of18O2/16O2suggests a concerted mechanism in O2addition. Deoxygenation, by reduction or O atom abstraction reagents, occurs for the 1-O addition complexes, while the 2-O, sulfinato, analogues are inert. The abstraction of oxygen from the 1-O, sulfenato species, is related to oxygen repair in soluble, NAD+-reducing [NiFe]-H2ase (Horch, M.; Lauterbach, L.; et al.J. Am. Chem. Soc.2015,137, 2555–2564).