Comparison of high-spin and low-spin nonheme Fe(III)-OOH complexes in O-O bond homolysis and H-atom abstraction reactivities.
Comparison of high-spin and low-spin nonheme Fe(III)-OOH complexes in O-O bond homolysis and H-atom abstraction reactivities.
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DOI：
10.1021/ja400183g
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发表时间：
2013-02-27
影响因子：
15
通讯作者：
Solomon, Edward I.
中科院分区：
文献类型：
--
作者：
Liu, Lei V.;Hong, Seungwoo;Cho, Jaeheung;Nam, Wonwoo;Solomon, Edward I.
通过光谱、计算和动力学研究了S = 5/2（HS）单核非血红素（TMC）FeIII-OOH络合物的几何结构、电子结构和反应活性，并与S = 1/2（LS）FeIII-OOH络合物的先前研究结果进行了比较，以了解O-O键均裂和亲电子H原子提取反应机制的异同。HS [（TMC）FeIII-OOH]2+配合物的均裂反应涉及轴向配体配位和O-O键均裂到LS表面。HS和LS FeIII-OOH配合物被发现进行直接的H-原子提取反应，但具有非常不同的反应坐标。对于LS FeIII-OOH，过渡态在O-O坐标中较晚，在C-H坐标中较早。然而，对于HS FeIII-OOH，过渡态在O-O中较早，并且进一步沿着C-H坐标。此外，在过渡态存在从衬底到HS FeIII-OOH的显著量的电子转移，但在LS过渡态中不发生。因此，与LS FeIII-OOH的行为相反，HS FeIII-OOH的H原子提取反应性被发现高度依赖于衬底的电离势和C-H键强度。LS FeIII-OOH被发现在强C-H键的H原子提取中更有效，而HS FeIII-OOH的更高还原电位允许其在亲电反应中具有活性而不需要O-O键断裂。这与Rieske双加氧酶有关，提出Rieske双加氧酶使用HS FeIII-OOH催化多种芳香族化合物的顺式二羟基化。
The geometric and electronic structures and reactivity of an S = 5/2 (HS) mononuclear non-heme (TMC)FeIII–OOH complex are studied by spectroscopies, calculations, and kinetics and compared with the results of previous studies of S = 1/2 (LS) FeIII–OOH complexes to understand parallels and differences in mechanisms of O–O bond homolysis and electrophilic H-atom abstraction reactions. The homolysis reaction of the HS [(TMC)FeIII–OOH]2+ complex is found to involve axial ligand coordination and a crossing to the LS surface for O–O bond homolysis. Both HS and LS FeIII–OOH complexes are found to perform direct H-atom abstraction reactions but with very different reaction coordinates. For the LS FeIII–OOH, the transition state is late in O–O and early in C–H coordinates. However, for the HS FeIII–OOH, the transition state is early in O–O and further along in the C–H coordinate. In addition, there is a significant amount of electron transfer from the substrate to the HS FeIII–OOH at transition state, but that does not occur in the LS transition state. Thus, in contrast to the behavior of LS FeIII–OOH, the H-atom abstraction reactivity of HS FeIII–OOH is found to be highly dependent on both the ionization potential and C–H bond strength of the substrate. LS FeIII–OOH is found to be more effective in H-atom abstraction for strong C–H bonds, while the higher reduction potential of HS FeIII–OOH allows it to be active in electrophilic reactions without the requirement of O–O bond cleavage. This is relevant to the Rieske dioxygenases, which are proposed to use a HS FeIII–OOH to catalyze cis-dihydroxylation of a wide range of aromatic compounds.
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DOI：
10.1002/oms.1210160604
发表时间：
1981-01-01
期刊：
ORGANIC MASS SPECTROMETRY
影响因子：
--
作者：
BOUCHOUX, G;DAGAUT, J
通讯作者：
DAGAUT, J
影响因子：
15
作者：
Kaizer, J;Klinker, EJ;Que, L
通讯作者：
Que, L
影响因子：
3.9
作者：
Hunter, TM;Paisey, SJ;Sadler, PJ
通讯作者：
Sadler, PJ
影响因子：
64.8
作者：
Cho, Jaeheung;Jeon, Sujin;Wilson, Samuel A.;Liu, Lei V.;Kang, Eun A.;Braymer, Joseph J.;Lim, Mi Hee;Hedman, Britt;Hodgson, Keith O.;Valentine, Joan Selverstone;Solomon, Edward I.;Nam, Wonwoo
通讯作者：
Nam, Wonwoo
影响因子：
15
作者：
Li, Feifei;Meier, Katlyn K.;Cranswick, Matthew A.;Chakrabarti, Mrinmoy;Van Heuvelen, Katherine M.;Muenck, Eckard;Que, Lawrence, Jr.
通讯作者：
Que, Lawrence, Jr.