Bioinorganic Chemistry Laboratory/Physical Chemistry, School of Chemistry, Madurai Kamaraj University, Madurai, 625021, India.
Anorganisch-Chemisches Institut and Interdisciplinary Center for Scientific Computing, Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany.
Chemistry. 2019 Jul 17;25(40):9540-9547. doi: 10.1002/chem.201901005. Epub 2019 Jun 24.
The iron(II) complexes [Fe(L)(MeCN) ](SO CF ) (L are two derivatives of tris(2-pyridyl)-based ligands) have been synthesized as models for cysteine dioxygenase (CDO). The molecular structure of one of the complexes exhibits octahedral coordination geometry and the Fe-N bond lengths [1.953(4)-1.972(4) Å] are similar to those in the Cys-bound Fe -CDO; Fe-N : 1.893-2.199 Å. The iron(II) centers of the model complexes exhibit relatively high Fe redox potentials (E =0.988-1.380 V vs. ferrocene/ferrocenium electrode, Fc/Fc ), within the range for O activation and typical for the corresponding nonheme iron enzymes. The reaction of in situ generated [Fe(L)(MeCN)(SPh)] with excess O in acetonitrile (MeCN) yields selectively the doubly oxygenated phenylsulfinic acid product. Isotopic labeling studies using O confirm the incorporation of both oxygen atoms of O into the product. Kinetic and preliminary DFT studies reveal the involvement of an Fe peroxido intermediate with a rhombic S= Fe center (687-696 nm; g≈2.46-2.48, 2.13-2.15, 1.92-1.94), similar to the spectroscopic signature of the low-spin Cys-bound Fe CDO (650 nm, g≈2.47, 2.29, 1.90). The proposed Fe peroxido intermediates have been trapped, and the O-O stretching frequencies are in the expected range (approximately 920 and 820 cm for the alkyl- and hydroperoxido species, respectively). The model complexes have a structure similar to that of the enzyme and structural aspects as well as the reactivity are discussed.
铁(II)配合物[Fe(L)(MeCN) ](SO CF )(L 是两种基于三(2-吡啶基)的配体的衍生物)已被合成作为半胱氨酸双加氧酶(CDO)的模型。其中一个配合物的分子结构呈现八面体配位几何形状，Fe-N 键长[1.953(4)-1.972(4) Å]与 Cys 结合的 Fe -CDO 中的相似；Fe-N: 1.893-2.199 Å。模型配合物中的铁(II)中心表现出相对较高的 Fe 氧化还原电位(E =0.988-1.380 V 相对于铁氰化铁/铁氰化物电极，Fc/Fc)，在 O 活化范围内，且典型的非血红素铁酶也是如此。在乙腈(MeCN)中，原位生成的[Fe(L)(MeCN)(SPh)]与过量 O 的反应选择性地生成双氧代苯亚磺酸产物。使用 O 的同位素标记研究证实了 O 的两个氧原子都掺入到产物中。动力学和初步的 DFT 研究表明，涉及具有菱形 S= Fe 中心的 Fe 过氧化物中间体(687-696 nm；g≈2.46-2.48, 2.13-2.15, 1.92-1.94)，类似于低自旋 Cys 结合的 Fe CDO 的光谱特征(650 nm，g≈2.47, 2.29, 1.90)。所提出的 Fe 过氧化物中间体已被捕获，O-O 伸缩频率在预期范围内(烷基和过氧物种的分别约为 920 和 820 cm)。模型配合物具有与酶相似的结构，讨论了结构方面和反应性。
