Electrochemical behaviour of mononuclear Fe(iii) complexes as models for oxygenases: reactivity of Fe(ii) species electrochemically formed in situ toward dioxygen
作者:Nak?dia M. F. Carvalho、O. A. C. Antunes、Adolfo Horn, Jr.
DOI:10.1039/b616377g
日期:——
In this paper, we report the electrochemical study of a family of mononuclear FeIII complexes [Fe(BMPA)Cl3] 1, [Fe(MPBMPA)Cl3] 2, [Fe(PBMPA)Cl2] 3 and [Fe(PABMPA)Cl2](ClO4) 4, where the ligand BMPA is bis-(2-pyridylmethyl)amine, and MPBMPA, PBMPA and PABMPA are the N-methylpropanoate, N-propanoate and N-propanamide BMPA-derivatives, respectively. It was possible to verify the influence of the different ligands on the redox properties of the complexes and from this to classify the complexes according to their Lewis acidity through the FeIII/FeII redox process, resulting in the following decreasing order in CH3CN solution: 4 > 2 > 1 > 3. The effect of the solvents CH3CN and DMSO on their electrochemical properties was also determined. Furthermore, we investigated the reactivity of the electrochemically-generated FeII complexes toward dioxygen and of the FeIII complexes toward superoxide through cyclic voltammetry. All the complexes reacted with dioxygen and superoxide in DMSO solution. Redox processes attributed to oxygenated species were observed in a more cathodic potential than those of the original compounds. According to the data, the new species FeII–O2 converts itself to FeIII–O2−, which presents a new redox wave attributed to the process FeIII–O2− + e−
→ FeII–O2−. The same species FeIII–O2− is formed from the reaction of the FeIII form of the complexes and KO2.
在本文中,我们报告了一系列单核 FeIII 配合物 [Fe(BMPA)Cl3] 1、[Fe(MPBMPA)Cl3] 2、[Fe(PBMPA)Cl2] 3 和 [Fe(PABMPA)Cl2] 的电化学研究(ClO4)4,其中配体BMPA是双-(2-吡啶基甲基)胺,MPBMPA、PBMPA和PABMPA分别是N-甲基丙酸酯、N-丙酸酯和N-丙酰胺BMPA衍生物。可以验证不同配体对配合物氧化还原性质的影响,并由此通过 FeIII/FeII 氧化还原过程根据其路易斯酸性对配合物进行分类,从而在 CH3CN 溶液中产生以下递减顺序: 4 > 2 > 1 > 3. 还确定了溶剂 CH3CN 和 DMSO 对其电化学性能的影响。此外,我们通过循环伏安法研究了电化学生成的 FeII 配合物对双氧的反应性以及 FeIII 配合物对超氧化物的反应性。所有配合物均在DMSO溶液中与分子氧和超氧化物反应。在比原始化合物更具阴极电位的情况下观察到归因于含氧物质的氧化还原过程。根据数据,新物质 FeII–O2 将自身转化为 FeIII–O2−,从而呈现出归因于 FeIII–O2− + e− 过程的新氧化还原波
→ FeII–O2−。复合物的 FeIII 形式与 KO2 反应形成相同种类的 FeIII–O2−。